[RFC PATCH 0/2] DRM driver for hyper-v synthetic video device

[RFC PATCH 0/2] DRM driver for hyper-v synthetic video device

[Deepak Rawat]

Hi All,

First draft of DRM driver for hyper-v synthetic video device. This synthetic
device is already supported by hyper-v and a corresponding framebuffer driver
exist at drivers/video/fbdev/hyperv_fb.c. With this patch, just reworked the
framebuffer driver into DRM, in doing so got mode-setting support. The code is
similar to cirrus DRM driver, using simple display pipe and shmem backed
GEM objects.

The device support more features like hardware cursor, EDID, multiple dirty
regions, etc, which were not supported with framebuffer driver. The plan is to
add support for those in future iteration. Wanted to get initial feedback and
discuss cursor support with simple kms helper. Is there any value to add cursor
support to drm_simple_kms_helper.c so that others can use it, or should I just
add cursor plane as device private? I believe we can still keep this driver
in drm/tiny?

For testing, ran GNOME and Weston with current changes in a Linux VM on
Windows 10 with hyper-v enabled.

Thanks,
Deepak

Deepak Rawat (2):
  drm/hyperv: Add DRM driver for hyperv synthetic video device
  MAINTAINERS: Add maintainer for hyperv video device

 MAINTAINERS                       |    8 +
 drivers/gpu/drm/tiny/Kconfig      |    9 +
 drivers/gpu/drm/tiny/Makefile     |    1 +
 drivers/gpu/drm/tiny/hyperv_drm.c | 1007 +++++++++++++++++++++++++++++
 4 files changed, 1025 insertions(+)
 create mode 100644 drivers/gpu/drm/tiny/hyperv_drm.c

-- 
2.27.0

[RFC PATCH 1/2] drm/hyperv: Add DRM driver for hyperv synthetic video device

[Deepak Rawat]

DRM driver for hyperv synthetic video device, based on hyperv_fb
framebuffer driver. Also added config option "DRM_HYPERV" to enabled
this driver.

Signed-off-by: Deepak Rawat <drawat.floss@gmail.com>
---
 drivers/gpu/drm/tiny/Kconfig      |    9 +
 drivers/gpu/drm/tiny/Makefile     |    1 +
 drivers/gpu/drm/tiny/hyperv_drm.c | 1007 +++++++++++++++++++++++++++++
 3 files changed, 1017 insertions(+)
 create mode 100644 drivers/gpu/drm/tiny/hyperv_drm.c

diff --git a/drivers/gpu/drm/tiny/Kconfig b/drivers/gpu/drm/tiny/Kconfig
index 2b6414f0fa75..e6d53e60a9c2 100644
--- a/drivers/gpu/drm/tiny/Kconfig
+++ b/drivers/gpu/drm/tiny/Kconfig
@@ -28,6 +28,15 @@ config DRM_GM12U320
 	 This is a KMS driver for projectors which use the GM12U320 chipset
 	 for video transfer over USB2/3, such as the Acer C120 mini projector.
 
+config DRM_HYPERV
+	tristate "DRM Support for hyperv synthetic video device"
+	depends on DRM && PCI && MMU && HYPERV
+	select DRM_KMS_HELPER
+	select DRM_GEM_SHMEM_HELPER
+	help
+	 This is a KMS driver for for hyperv synthetic video device.
+	 If M is selected the module will be called hyperv_drm.
+
 config TINYDRM_HX8357D
 	tristate "DRM support for HX8357D display panels"
 	depends on DRM && SPI
diff --git a/drivers/gpu/drm/tiny/Makefile b/drivers/gpu/drm/tiny/Makefile
index 6ae4e9e5a35f..837cb2c2637e 100644
--- a/drivers/gpu/drm/tiny/Makefile
+++ b/drivers/gpu/drm/tiny/Makefile
@@ -2,6 +2,7 @@
 
 obj-$(CONFIG_DRM_CIRRUS_QEMU)		+= cirrus.o
 obj-$(CONFIG_DRM_GM12U320)		+= gm12u320.o
+obj-$(CONFIG_DRM_HYPERV)		+= hyperv_drm.o
 obj-$(CONFIG_TINYDRM_HX8357D)		+= hx8357d.o
 obj-$(CONFIG_TINYDRM_ILI9225)		+= ili9225.o
 obj-$(CONFIG_TINYDRM_ILI9341)		+= ili9341.o
diff --git a/drivers/gpu/drm/tiny/hyperv_drm.c b/drivers/gpu/drm/tiny/hyperv_drm.c
new file mode 100644
index 000000000000..3d020586056e
--- /dev/null
+++ b/drivers/gpu/drm/tiny/hyperv_drm.c
@@ -0,0 +1,1007 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2012-2020 Microsoft
+ *
+ * Authors:
+ * Deepak Rawat <drawat.floss@gmail.com>
+ *
+ * Portions of this code is derived from hyperv_fb.c
+ * drivers/video/fbdev/hyperv_fb.c - framebuffer driver for hyperv synthetic
+ * video device.
+ *
+ */
+
+#include <linux/console.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/hyperv.h>
+
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_atomic_state_helper.h>
+#include <drm/drm_connector.h>
+#include <drm/drm_damage_helper.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_fb_helper.h>
+#include <drm/drm_file.h>
+#include <drm/drm_format_helper.h>
+#include <drm/drm_fourcc.h>
+#include <drm/drm_gem_shmem_helper.h>
+#include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_ioctl.h>
+#include <drm/drm_managed.h>
+#include <drm/drm_modeset_helper_vtables.h>
+#include <drm/drm_probe_helper.h>
+#include <drm/drm_simple_kms_helper.h>
+
+#define DRIVER_NAME "hyperv_drm"
+#define DRIVER_DESC "DRM driver for hyperv synthetic video device"
+#define DRIVER_DATE "2020"
+#define DRIVER_MAJOR 1
+#define DRIVER_MINOR 0
+
+#define VMBUS_MAX_PACKET_SIZE 0x4000
+#define VMBUS_RING_BUFSIZE (256 * 1024)
+#define VMBUS_VSP_TIMEOUT (10 * HZ)
+
+#define PCI_VENDOR_ID_MICROSOFT 0x1414
+#define PCI_DEVICE_ID_HYPERV_VIDEO 0x5353
+
+struct hyperv_device {
+	/* drm */
+	struct drm_device dev;
+	struct drm_simple_display_pipe pipe;
+	struct drm_connector connector;
+
+	/* mode */
+	u32 screen_width_max;
+	u32 screen_height_max;
+	u32 preferred_width;
+	u32 preferred_height;
+	u32 screen_depth;
+
+	/* hw */
+	void __iomem *vram;
+	unsigned long fb_base;
+	unsigned long fb_size;
+	struct completion wait;
+	u32 synthvid_version;
+	u32 mmio_megabytes;
+	bool init_done;
+
+	u8 init_buf[VMBUS_MAX_PACKET_SIZE];
+	u8 recv_buf[VMBUS_MAX_PACKET_SIZE];
+
+	struct hv_device *hdev;
+};
+
+#define to_hv(_dev) container_of(_dev, struct hyperv_device, dev)
+
+/* ---------------------------------------------------------------------- */
+/* Hyper-V Synthetic Video Protocol                                       */
+
+#define SYNTHVID_VERSION(major, minor) ((minor) << 16 | (major))
+#define SYNTHVID_VER_GET_MAJOR(ver) (ver & 0x0000ffff)
+#define SYNTHVID_VER_GET_MINOR(ver) ((ver & 0xffff0000) >> 16)
+#define SYNTHVID_VERSION_WIN7 SYNTHVID_VERSION(3, 0)
+#define SYNTHVID_VERSION_WIN8 SYNTHVID_VERSION(3, 2)
+#define SYNTHVID_VERSION_WIN10 SYNTHVID_VERSION(3, 5)
+
+#define SYNTHVID_DEPTH_WIN7 16
+#define SYNTHVID_DEPTH_WIN8 32
+#define SYNTHVID_FB_SIZE_WIN7 (4 * 1024 * 1024)
+#define SYNTHVID_FB_SIZE_WIN8 (8 * 1024 * 1024)
+#define SYNTHVID_WIDTH_MAX_WIN7 1600
+#define SYNTHVID_HEIGHT_MAX_WIN7 1200
+
+enum pipe_msg_type {
+	PIPE_MSG_INVALID,
+	PIPE_MSG_DATA,
+	PIPE_MSG_MAX
+};
+
+enum synthvid_msg_type {
+	SYNTHVID_ERROR			= 0,
+	SYNTHVID_VERSION_REQUEST	= 1,
+	SYNTHVID_VERSION_RESPONSE	= 2,
+	SYNTHVID_VRAM_LOCATION		= 3,
+	SYNTHVID_VRAM_LOCATION_ACK	= 4,
+	SYNTHVID_SITUATION_UPDATE	= 5,
+	SYNTHVID_SITUATION_UPDATE_ACK	= 6,
+	SYNTHVID_POINTER_POSITION	= 7,
+	SYNTHVID_POINTER_SHAPE		= 8,
+	SYNTHVID_FEATURE_CHANGE		= 9,
+	SYNTHVID_DIRT			= 10,
+	SYNTHVID_RESOLUTION_REQUEST	= 13,
+	SYNTHVID_RESOLUTION_RESPONSE	= 14,
+
+	SYNTHVID_MAX			= 15
+};
+
+struct pipe_msg_hdr {
+	u32 type;
+	u32 size; /* size of message after this field */
+} __packed;
+
+struct hvd_screen_info {
+	u16 width;
+	u16 height;
+} __packed;
+
+struct synthvid_msg_hdr {
+	u32 type;
+	u32 size;  /* size of this header + payload after this field*/
+} __packed;
+
+struct synthvid_version_req {
+	u32 version;
+} __packed;
+
+struct synthvid_version_resp {
+	u32 version;
+	u8 is_accepted;
+	u8 max_video_outputs;
+} __packed;
+
+struct synthvid_vram_location {
+	u64 user_ctx;
+	u8 is_vram_gpa_specified;
+	u64 vram_gpa;
+} __packed;
+
+struct synthvid_vram_location_ack {
+	u64 user_ctx;
+} __packed;
+
+struct video_output_situation {
+	u8 active;
+	u32 vram_offset;
+	u8 depth_bits;
+	u32 width_pixels;
+	u32 height_pixels;
+	u32 pitch_bytes;
+} __packed;
+
+struct synthvid_situation_update {
+	u64 user_ctx;
+	u8 video_output_count;
+	struct video_output_situation video_output[1];
+} __packed;
+
+struct synthvid_situation_update_ack {
+	u64 user_ctx;
+} __packed;
+
+struct synthvid_pointer_position {
+	u8 is_visible;
+	u8 video_output;
+	s32 image_x;
+	s32 image_y;
+} __packed;
+
+#define SYNTHVID_CURSOR_MAX_X 96
+#define SYNTHVID_CURSOR_MAX_Y 96
+#define SYNTHVID_CURSOR_ARGB_PIXEL_SIZE 4
+#define SYNTHVID_CURSOR_MAX_SIZE (SYNTHVID_CURSOR_MAX_X * \
+	SYNTHVID_CURSOR_MAX_Y * SYNTHVID_CURSOR_ARGB_PIXEL_SIZE)
+#define SYNTHVID_CURSOR_COMPLETE (-1)
+
+struct synthvid_pointer_shape {
+	u8 part_idx;
+	u8 is_argb;
+	u32 width; /* SYNTHVID_CURSOR_MAX_X at most */
+	u32 height; /* SYNTHVID_CURSOR_MAX_Y at most */
+	u32 hot_x; /* hotspot relative to upper-left of pointer image */
+	u32 hot_y;
+	u8 data[4];
+} __packed;
+
+struct synthvid_feature_change {
+	u8 is_dirt_needed;
+	u8 is_ptr_pos_needed;
+	u8 is_ptr_shape_needed;
+	u8 is_situ_needed;
+} __packed;
+
+struct rect {
+	s32 x1, y1; /* top left corner */
+	s32 x2, y2; /* bottom right corner, exclusive */
+} __packed;
+
+struct synthvid_dirt {
+	u8 video_output;
+	u8 dirt_count;
+	struct rect rect[1];
+} __packed;
+
+#define SYNTHVID_EDID_BLOCK_SIZE	128
+#define	SYNTHVID_MAX_RESOLUTION_COUNT	64
+
+struct synthvid_supported_resolution_req {
+	u8 maximum_resolution_count;
+} __packed;
+
+struct synthvid_supported_resolution_resp {
+	u8 edid_block[SYNTHVID_EDID_BLOCK_SIZE];
+	u8 resolution_count;
+	u8 default_resolution_index;
+	u8 is_standard;
+	struct hvd_screen_info supported_resolution[SYNTHVID_MAX_RESOLUTION_COUNT];
+} __packed;
+
+struct synthvid_msg {
+	struct pipe_msg_hdr pipe_hdr;
+	struct synthvid_msg_hdr vid_hdr;
+	union {
+		struct synthvid_version_req ver_req;
+		struct synthvid_version_resp ver_resp;
+		struct synthvid_vram_location vram;
+		struct synthvid_vram_location_ack vram_ack;
+		struct synthvid_situation_update situ;
+		struct synthvid_situation_update_ack situ_ack;
+		struct synthvid_pointer_position ptr_pos;
+		struct synthvid_pointer_shape ptr_shape;
+		struct synthvid_feature_change feature_chg;
+		struct synthvid_dirt dirt;
+		struct synthvid_supported_resolution_req resolution_req;
+		struct synthvid_supported_resolution_resp resolution_resp;
+	};
+} __packed;
+
+static inline bool synthvid_ver_ge(u32 ver1, u32 ver2)
+{
+	if (SYNTHVID_VER_GET_MAJOR(ver1) > SYNTHVID_VER_GET_MAJOR(ver2) ||
+	    (SYNTHVID_VER_GET_MAJOR(ver1) == SYNTHVID_VER_GET_MAJOR(ver2) &&
+	     SYNTHVID_VER_GET_MINOR(ver1) >= SYNTHVID_VER_GET_MINOR(ver2)))
+		return true;
+
+	return false;
+}
+
+static inline int synthvid_send(struct hv_device *hdev,
+				struct synthvid_msg *msg)
+{
+	static atomic64_t request_id = ATOMIC64_INIT(0);
+	int ret;
+
+	msg->pipe_hdr.type = PIPE_MSG_DATA;
+	msg->pipe_hdr.size = msg->vid_hdr.size;
+
+	ret = vmbus_sendpacket(hdev->channel, msg,
+			       msg->vid_hdr.size + sizeof(struct pipe_msg_hdr),
+			       atomic64_inc_return(&request_id),
+			       VM_PKT_DATA_INBAND, 0);
+
+	if (ret)
+		DRM_ERROR("Unable to send packet via vmbus\n");
+
+	return ret;
+}
+
+static int synthvid_negotiate_ver(struct hv_device *hdev, u32 ver)
+{
+	struct hyperv_device *hv = hv_get_drvdata(hdev);
+	struct synthvid_msg *msg = (struct synthvid_msg *)hv->init_buf;
+	unsigned long t;
+	int ret = 0;
+
+	memset(msg, 0, sizeof(struct synthvid_msg));
+	msg->vid_hdr.type = SYNTHVID_VERSION_REQUEST;
+	msg->vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
+		sizeof(struct synthvid_version_req);
+	msg->ver_req.version = ver;
+	synthvid_send(hdev, msg);
+
+	t = wait_for_completion_timeout(&hv->wait, VMBUS_VSP_TIMEOUT);
+	if (!t) {
+		DRM_ERROR("Time out on waiting version response\n");
+		ret = -ETIMEDOUT;
+		goto out;
+	}
+	if (!msg->ver_resp.is_accepted) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	hv->synthvid_version = ver;
+	DRM_INFO("Synthvid Version major %d, minor %d\n",
+		 SYNTHVID_VER_GET_MAJOR(ver), SYNTHVID_VER_GET_MINOR(ver));
+
+out:
+	return ret;
+}
+
+/* Should be done only once during init and resume */
+static int synthvid_update_vram_location(struct hv_device *hdev,
+					  phys_addr_t vram_pp)
+{
+	struct hyperv_device *hv = hv_get_drvdata(hdev);
+	struct synthvid_msg *msg = (struct synthvid_msg *)hv->init_buf;
+	unsigned long t;
+	int ret = 0;
+
+	memset(msg, 0, sizeof(struct synthvid_msg));
+	msg->vid_hdr.type = SYNTHVID_VRAM_LOCATION;
+	msg->vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
+		sizeof(struct synthvid_vram_location);
+	msg->vram.user_ctx = msg->vram.vram_gpa = vram_pp;
+	msg->vram.is_vram_gpa_specified = 1;
+	synthvid_send(hdev, msg);
+
+	t = wait_for_completion_timeout(&hv->wait, VMBUS_VSP_TIMEOUT);
+	if (!t) {
+		DRM_ERROR("Time out on waiting vram location ack\n");
+		ret = -ETIMEDOUT;
+		goto out;
+	}
+	if (msg->vram_ack.user_ctx != vram_pp) {
+		DRM_ERROR("Unable to set VRAM location\n");
+		ret = -ENODEV;
+	}
+
+out:
+	return ret;
+}
+
+static int synthvid_update_situation(struct hv_device *hdev, u8 active, u32 bpp,
+				     u32 w, u32 h, u32 pitch)
+{
+	struct synthvid_msg msg;
+
+	memset(&msg, 0, sizeof(struct synthvid_msg));
+
+	msg.vid_hdr.type = SYNTHVID_SITUATION_UPDATE;
+	msg.vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
+		sizeof(struct synthvid_situation_update);
+	msg.situ.user_ctx = 0;
+	msg.situ.video_output_count = 1;
+	msg.situ.video_output[0].active = active;
+	/* vram_offset should always be 0 */
+	msg.situ.video_output[0].vram_offset = 0;
+	msg.situ.video_output[0].depth_bits = bpp;
+	msg.situ.video_output[0].width_pixels = w;
+	msg.situ.video_output[0].height_pixels = h;
+	msg.situ.video_output[0].pitch_bytes = pitch;
+
+	synthvid_send(hdev, &msg);
+
+	return 0;
+}
+
+static int synthvid_update_dirt(struct hv_device *hdev, struct drm_rect *rect)
+{
+	struct synthvid_msg msg;
+
+	memset(&msg, 0, sizeof(struct synthvid_msg));
+
+	msg.vid_hdr.type = SYNTHVID_DIRT;
+	msg.vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
+		sizeof(struct synthvid_dirt);
+	msg.dirt.video_output = 0;
+	msg.dirt.dirt_count = 1;
+	msg.dirt.rect[0].x1 = rect->x1;
+	msg.dirt.rect[0].y1 = rect->y1;
+	msg.dirt.rect[0].x2 = rect->x2;
+	msg.dirt.rect[0].y2 = rect->y2;
+
+	synthvid_send(hdev, &msg);
+
+	return 0;
+}
+
+static int synthvid_get_supported_resolution(struct hv_device *hdev)
+{
+	struct hyperv_device *hv = hv_get_drvdata(hdev);
+	struct synthvid_msg *msg = (struct synthvid_msg *)hv->init_buf;
+	unsigned long t;
+	int ret = 0;
+	u8 index;
+	int i;
+
+	memset(msg, 0, sizeof(struct synthvid_msg));
+	msg->vid_hdr.type = SYNTHVID_RESOLUTION_REQUEST;
+	msg->vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
+		sizeof(struct synthvid_supported_resolution_req);
+	msg->resolution_req.maximum_resolution_count =
+		SYNTHVID_MAX_RESOLUTION_COUNT;
+	synthvid_send(hdev, msg);
+
+	t = wait_for_completion_timeout(&hv->wait, VMBUS_VSP_TIMEOUT);
+	if (!t) {
+		DRM_ERROR("Time out on waiting resolution response\n");
+		ret = -ETIMEDOUT;
+		goto out;
+	}
+
+	if (msg->resolution_resp.resolution_count == 0) {
+		DRM_ERROR("No supported resolutions\n");
+		ret = -ENODEV;
+		goto out;
+	}
+
+	index = msg->resolution_resp.default_resolution_index;
+	if (index >= msg->resolution_resp.resolution_count) {
+		DRM_ERROR("Invalid resolution index: %d\n", index);
+		ret = -ENODEV;
+		goto out;
+	}
+
+	for (i = 0; i < msg->resolution_resp.resolution_count; i++) {
+		hv->screen_width_max = max_t(u32, hv->screen_width_max,
+			msg->resolution_resp.supported_resolution[i].width);
+		hv->screen_height_max = max_t(u32, hv->screen_height_max,
+			msg->resolution_resp.supported_resolution[i].height);
+	}
+
+	hv->preferred_width =
+		msg->resolution_resp.supported_resolution[index].width;
+	hv->preferred_height =
+		msg->resolution_resp.supported_resolution[index].height;
+
+out:
+	return ret;
+}
+
+/* Actions on received messages from host */
+static void synthvid_recv_sub(struct hv_device *hdev)
+{
+	struct hyperv_device *hv = hv_get_drvdata(hdev);
+	struct synthvid_msg *msg;
+
+	if (!hv)
+		return;
+
+	msg = (struct synthvid_msg *)hv->recv_buf;
+
+	/* Complete the wait event */
+	if (msg->vid_hdr.type == SYNTHVID_VERSION_RESPONSE ||
+	    msg->vid_hdr.type == SYNTHVID_RESOLUTION_RESPONSE ||
+	    msg->vid_hdr.type == SYNTHVID_VRAM_LOCATION_ACK) {
+		memcpy(hv->init_buf, msg, VMBUS_MAX_PACKET_SIZE);
+		complete(&hv->wait);
+		return;
+	}
+}
+
+static void synthvid_receive(void *ctx)
+{
+	struct hv_device *hdev = ctx;
+	struct hyperv_device *hv = hv_get_drvdata(hdev);
+	struct synthvid_msg *recv_buf;
+	u32 bytes_recvd;
+	u64 req_id;
+	int ret;
+
+	if (!hv)
+		return;
+
+	recv_buf = (struct synthvid_msg *)hv->recv_buf;
+
+	do {
+		ret = vmbus_recvpacket(hdev->channel, recv_buf,
+				       VMBUS_MAX_PACKET_SIZE,
+				       &bytes_recvd, &req_id);
+		if (bytes_recvd > 0 &&
+		    recv_buf->pipe_hdr.type == PIPE_MSG_DATA)
+			synthvid_recv_sub(hdev);
+	} while (bytes_recvd > 0 && ret == 0);
+}
+
+static int synthvid_connect_vsp(struct hv_device *hdev)
+{
+	struct hyperv_device *hv = hv_get_drvdata(hdev);
+	int ret;
+
+	ret = vmbus_open(hdev->channel, VMBUS_RING_BUFSIZE, VMBUS_RING_BUFSIZE,
+			 NULL, 0, synthvid_receive, hdev);
+	if (ret) {
+		DRM_ERROR("Unable to open vmbus channel\n");
+		return ret;
+	}
+
+	/* Negotiate the protocol version with host */
+	switch (vmbus_proto_version) {
+	case VERSION_WIN10:
+	case VERSION_WIN10_V5:
+		ret = synthvid_negotiate_ver(hdev, SYNTHVID_VERSION_WIN10);
+		if (!ret)
+			break;
+		fallthrough;
+	case VERSION_WIN8:
+	case VERSION_WIN8_1:
+		ret = synthvid_negotiate_ver(hdev, SYNTHVID_VERSION_WIN8);
+		if (!ret)
+			break;
+		fallthrough;
+	case VERSION_WS2008:
+	case VERSION_WIN7:
+		ret = synthvid_negotiate_ver(hdev, SYNTHVID_VERSION_WIN7);
+		break;
+	default:
+		ret = synthvid_negotiate_ver(hdev, SYNTHVID_VERSION_WIN10);
+		break;
+	}
+
+	if (ret) {
+		DRM_ERROR("Synthetic video device version not accepted\n");
+		goto error;
+	}
+
+	if (hv->synthvid_version == SYNTHVID_VERSION_WIN7)
+		hv->screen_depth = SYNTHVID_DEPTH_WIN7;
+	else
+		hv->screen_depth = SYNTHVID_DEPTH_WIN8;
+
+	if (synthvid_ver_ge(hv->synthvid_version, SYNTHVID_VERSION_WIN10)) {
+		ret = synthvid_get_supported_resolution(hdev);
+		if (ret)
+			DRM_ERROR("Failed to get supported resolution from host, use default\n");
+	} else {
+		hv->screen_width_max = SYNTHVID_WIDTH_MAX_WIN7;
+		hv->screen_height_max = SYNTHVID_HEIGHT_MAX_WIN7;
+	}
+
+	hv->mmio_megabytes = hdev->channel->offermsg.offer.mmio_megabytes;
+
+	return 0;
+
+error:
+	vmbus_close(hdev->channel);
+	return ret;
+}
+
+/* ---------------------------------------------------------------------- */
+/* VRAM blit                                                              */
+
+static int hyperv_blit_to_vram_rect(struct drm_framebuffer *fb,
+				    struct drm_rect *rect)
+{
+	struct hyperv_device *hv = to_hv(fb->dev);
+	void *vmap;
+	int idx, ret;
+
+	ret = -ENODEV;
+	if (!drm_dev_enter(&hv->dev, &idx))
+		goto out;
+
+	ret = -ENOMEM;
+	vmap = drm_gem_shmem_vmap(fb->obj[0]);
+	if (!vmap)
+		goto out_dev_exit;
+
+	drm_fb_memcpy_dstclip(hv->vram, vmap, fb, rect);
+	drm_gem_shmem_vunmap(fb->obj[0], vmap);
+	ret = 0;
+
+out_dev_exit:
+	drm_dev_exit(idx);
+out:
+	return ret;
+}
+
+static int hyperv_blit_to_vram_fullscreen(struct drm_framebuffer *fb)
+{
+	struct drm_rect fullscreen = {
+		.x1 = 0,
+		.x2 = fb->width,
+		.y1 = 0,
+		.y2 = fb->height,
+	};
+	return hyperv_blit_to_vram_rect(fb, &fullscreen);
+}
+
+/* ---------------------------------------------------------------------- */
+/* connector                                                              */
+
+static int hyperv_connector_get_modes(struct drm_connector *connector)
+{
+	struct hyperv_device *hv = to_hv(connector->dev);
+	int count;
+
+	count = drm_add_modes_noedid(connector,
+				     connector->dev->mode_config.max_width,
+				     connector->dev->mode_config.max_height);
+	drm_set_preferred_mode(connector, hv->preferred_width,
+			       hv->preferred_height);
+
+	return count;
+}
+
+static const struct drm_connector_helper_funcs hyperv_connector_helper_funcs = {
+	.get_modes = hyperv_connector_get_modes,
+};
+
+static const struct drm_connector_funcs hyperv_connector_funcs = {
+	.fill_modes = drm_helper_probe_single_connector_modes,
+	.destroy = drm_connector_cleanup,
+	.reset = drm_atomic_helper_connector_reset,
+	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+};
+
+static int hyperv_conn_init(struct hyperv_device *hv)
+{
+	drm_connector_helper_add(&hv->connector, &hyperv_connector_helper_funcs);
+	return drm_connector_init(&hv->dev, &hv->connector,
+				  &hyperv_connector_funcs,
+				  DRM_MODE_CONNECTOR_VGA);
+
+}
+
+/* ---------------------------------------------------------------------- */
+/* display pipe                                                           */
+
+static int hyperv_check_size(struct hyperv_device *hv, int w, int h,
+			     struct drm_framebuffer *fb)
+{
+	u32 pitch = w * (hv->screen_depth/8);
+
+	if (fb)
+		pitch = fb->pitches[0];
+
+	if (pitch * h > hv->fb_size)
+		return -EINVAL;
+
+	return 0;
+}
+
+static enum drm_mode_status
+hyperv_pipe_mode_valid(struct drm_simple_display_pipe *pipe,
+		       const struct drm_display_mode *mode)
+{
+	struct hyperv_device *hv = to_hv(pipe->crtc.dev);
+
+	if (hyperv_check_size(hv, mode->hdisplay, mode->vdisplay, NULL))
+		return MODE_BAD;
+
+	return MODE_OK;
+}
+
+static void hyperv_pipe_enable(struct drm_simple_display_pipe *pipe,
+			       struct drm_crtc_state *crtc_state,
+			       struct drm_plane_state *plane_state)
+{
+	struct hyperv_device *hv = to_hv(pipe->crtc.dev);
+
+	synthvid_update_situation(hv->hdev, 1,  hv->screen_depth,
+				  crtc_state->mode.hdisplay,
+				  crtc_state->mode.vdisplay,
+				  plane_state->fb->pitches[0]);
+	hyperv_blit_to_vram_fullscreen(plane_state->fb);
+}
+
+static void hyperv_pipe_update(struct drm_simple_display_pipe *pipe,
+			      struct drm_plane_state *old_state)
+{
+	struct hyperv_device *hv = to_hv(pipe->crtc.dev);
+	struct drm_plane_state *state = pipe->plane.state;
+	struct drm_rect rect;
+
+	if (drm_atomic_helper_damage_merged(old_state, state, &rect)) {
+		hyperv_blit_to_vram_rect(state->fb, &rect);
+		synthvid_update_dirt(hv->hdev, &rect);
+	}
+}
+
+static const struct drm_simple_display_pipe_funcs hyperv_pipe_funcs = {
+	.mode_valid = hyperv_pipe_mode_valid,
+	.enable	= hyperv_pipe_enable,
+	.update	= hyperv_pipe_update,
+};
+
+static const uint32_t hyperv_formats[] = {
+	DRM_FORMAT_XRGB8888,
+};
+
+static const uint64_t hyperv_modifiers[] = {
+	DRM_FORMAT_MOD_LINEAR,
+	DRM_FORMAT_MOD_INVALID
+};
+
+static int hyperv_pipe_init(struct hyperv_device *hv)
+{
+	int ret;
+
+	ret = drm_simple_display_pipe_init(&hv->dev,
+					   &hv->pipe,
+					   &hyperv_pipe_funcs,
+					   hyperv_formats,
+					   ARRAY_SIZE(hyperv_formats),
+					   NULL,
+					   &hv->connector);
+
+	drm_plane_enable_fb_damage_clips(&(hv->pipe.plane));
+
+	return ret;
+}
+
+/* ---------------------------------------------------------------------- */
+/* framebuffers & mode config                                             */
+
+static struct drm_framebuffer*
+hyperv_fb_create(struct drm_device *dev, struct drm_file *file_priv,
+		 const struct drm_mode_fb_cmd2 *mode_cmd)
+{
+	struct hyperv_device *hv = to_hv(dev);
+
+	if (mode_cmd->pixel_format != DRM_FORMAT_XRGB8888)
+		return ERR_PTR(-EINVAL);
+
+	if (mode_cmd->pitches[0] * mode_cmd->height > hv->fb_size)
+		return ERR_PTR(-EINVAL);
+
+	return drm_gem_fb_create_with_dirty(dev, file_priv, mode_cmd);
+}
+
+static const struct drm_mode_config_funcs hyperv_mode_config_funcs = {
+	.fb_create = hyperv_fb_create,
+	.atomic_check = drm_atomic_helper_check,
+	.atomic_commit = drm_atomic_helper_commit,
+};
+
+static int hyperv_mode_config_init(struct hyperv_device *hv)
+{
+	struct drm_device *dev = &hv->dev;
+	int ret;
+
+	ret = drmm_mode_config_init(dev);
+	if (ret)
+		return ret;
+
+	dev->mode_config.min_width = 0;
+	dev->mode_config.min_height = 0;
+	dev->mode_config.max_width = hv->screen_width_max;
+	dev->mode_config.max_height = hv->screen_height_max;
+
+	dev->mode_config.preferred_depth = hv->screen_depth;
+	dev->mode_config.prefer_shadow = 0;
+
+	dev->mode_config.funcs = &hyperv_mode_config_funcs;
+
+	return 0;
+}
+
+/* ---------------------------------------------------------------------- */
+/* DRM                                                                    */
+
+DEFINE_DRM_GEM_FOPS(hv_fops);
+
+static struct drm_driver hyperv_driver = {
+	.driver_features = DRIVER_MODESET | DRIVER_GEM | DRIVER_ATOMIC,
+
+	.name		 = DRIVER_NAME,
+	.desc		 = DRIVER_DESC,
+	.date		 = DRIVER_DATE,
+	.major		 = DRIVER_MAJOR,
+	.minor		 = DRIVER_MINOR,
+
+	.fops		 = &hv_fops,
+	DRM_GEM_SHMEM_DRIVER_OPS,
+};
+
+/* ---------------------------------------------------------------------- */
+/* pci/vmbus interface                                                    */
+
+static int hyperv_pci_probe(struct pci_dev *pdev,
+			    const struct pci_device_id *ent)
+{
+	return 0;
+}
+
+static void hyperv_pci_remove(struct pci_dev *pdev)
+{
+}
+
+static const struct pci_device_id hyperv_pci_tbl[] = {
+	{
+		.vendor = PCI_VENDOR_ID_MICROSOFT,
+		.device = PCI_DEVICE_ID_HYPERV_VIDEO,
+	},
+	{ /* end of list */ }
+};
+
+static struct pci_driver hyperv_pci_driver = {
+	.name =		KBUILD_MODNAME,
+	.id_table =	hyperv_pci_tbl,
+	.probe =	hyperv_pci_probe,
+	.remove =	hyperv_pci_remove,
+};
+
+static int hyperv_vmbus_probe(struct hv_device *hdev,
+			      const struct hv_vmbus_device_id *dev_id)
+{
+	struct hyperv_device *hv;
+	struct drm_device *dev;
+	struct pci_dev *pdev;
+	int ret;
+
+	hv = devm_drm_dev_alloc(&hdev->device, &hyperv_driver,
+				struct hyperv_device, dev);
+	if (IS_ERR(hv))
+		return PTR_ERR(hv);
+
+	dev = &hv->dev;
+	init_completion(&hv->wait);
+	hv_set_drvdata(hdev, hv);
+	hv->hdev = hdev;
+
+	pdev = pci_get_device(PCI_VENDOR_ID_MICROSOFT,
+			      PCI_DEVICE_ID_HYPERV_VIDEO, NULL);
+	if (!pdev) {
+		DRM_ERROR("Unable to find PCI Hyper-V video\n");
+		return -ENODEV;
+	}
+
+	ret = drm_fb_helper_remove_conflicting_pci_framebuffers(pdev, "hypervdrmfb");
+	if (ret) {
+		DRM_ERROR("Not able to remove boot fb\n");
+		goto error;
+	}
+
+	if (pci_request_region(pdev, 0, DRIVER_NAME) != 0)
+		DRM_WARN("Cannot request framebuffer, boot fb still active?\n");
+
+	if ((pdev->resource[0].flags & IORESOURCE_MEM) == 0) {
+		DRM_ERROR("Resource at bar 0 is not IORESOURCE_MEM\n");
+		ret = -ENODEV;
+		goto error;
+	}
+
+	hv->fb_base = pci_resource_start(pdev, 0);
+	hv->fb_size = pci_resource_len(pdev, 0);
+	if (hv->fb_base == 0) {
+		DRM_ERROR("Resource not available\n");
+		ret = -ENODEV;
+		goto error;
+	}
+
+	/* Get the actual VRAM size from the device */
+	ret = synthvid_connect_vsp(hdev);
+	if (ret) {
+		DRM_ERROR("Failed to connect to vmbus\n");
+		goto error;
+	}
+
+	hv->fb_size = min(hv->fb_size,
+			  (unsigned long)(hv->mmio_megabytes * 1024 * 1024));
+	hv->vram = devm_ioremap(&pdev->dev, hv->fb_base, hv->fb_size);
+	if (hv->vram == NULL) {
+		DRM_ERROR("Failed to map vram\n");
+		ret = -ENOMEM;
+		goto error1;
+	}
+
+	/*
+	 * Failing to update vram location is not fatal. Device will update
+	 * dirty area till preferred resolution only.
+	 */
+	ret = synthvid_update_vram_location(hdev, hv->fb_base);
+	if (ret)
+		DRM_WARN("Failed to update vram location.\n");
+
+	ret = hyperv_mode_config_init(hv);
+	if (ret) {
+		DRM_ERROR("Failed to initialized mode setting\n");
+		goto error1;
+	}
+
+	ret = hyperv_conn_init(hv);
+	if (ret) {
+		DRM_ERROR("Failed to initialized connector\n");
+		goto error1;
+	}
+
+	ret = hyperv_pipe_init(hv);
+	if (ret) {
+		DRM_ERROR("Failed to initialized pipe\n");
+		goto error1;
+	}
+
+	drm_mode_config_reset(dev);
+
+	ret = drm_dev_register(dev, 0);
+	if (ret) {
+		DRM_ERROR("Failed to register drm driver\n");
+		goto error1;
+	}
+
+	drm_fbdev_generic_setup(dev, dev->mode_config.preferred_depth);
+
+	pci_dev_put(pdev);
+	return 0;
+
+error1:
+	vmbus_close(hdev->channel);
+error:
+	hv_set_drvdata(hdev, NULL);
+	pci_dev_put(pdev);
+	return ret;
+}
+
+static int hyperv_vmbus_remove(struct hv_device *hdev)
+{
+	struct drm_device *dev = hv_get_drvdata(hdev);
+
+	drm_dev_unplug(dev);
+	drm_atomic_helper_shutdown(dev);
+	vmbus_close(hdev->channel);
+	hv_set_drvdata(hdev, NULL);
+
+	return 0;
+}
+
+static int hyperv_vmbus_suspend(struct hv_device *hdev)
+{
+	struct drm_device *dev = hv_get_drvdata(hdev);
+	int ret;
+
+	ret = drm_mode_config_helper_suspend(dev);
+
+	vmbus_close(hdev->channel);
+
+	return ret;
+}
+
+static int hyperv_vmbus_resume(struct hv_device *hdev)
+{
+	struct drm_device *dev = hv_get_drvdata(hdev);
+	int ret;
+
+	ret = synthvid_connect_vsp(hdev);
+	if (ret)
+		return ret;
+
+	return drm_mode_config_helper_resume(dev);
+}
+
+static const struct hv_vmbus_device_id hyperv_vmbus_tbl[] = {
+	/* Synthetic Video Device GUID */
+	{HV_SYNTHVID_GUID},
+	{}
+};
+
+static struct hv_driver hyperv_hv_driver = {
+	.name = KBUILD_MODNAME,
+	.id_table = hyperv_vmbus_tbl,
+	.probe = hyperv_vmbus_probe,
+	.remove = hyperv_vmbus_remove,
+	.suspend = hyperv_vmbus_suspend,
+	.resume = hyperv_vmbus_resume,
+	.driver = {
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+};
+
+/* ---------------------------------------------------------------------- */
+/* module init/exit                                                       */
+
+static int __init hyperv_init(void)
+{
+	int ret;
+
+	ret = pci_register_driver(&hyperv_pci_driver);
+	if (ret != 0) {
+		DRM_ERROR("Failed to register pci driver\n");
+		return ret;
+	}
+
+	ret = vmbus_driver_register(&hyperv_hv_driver);
+	if (ret != 0)
+		DRM_ERROR("Failed to register vmbus driver\n");
+
+	return ret;
+}
+
+static void __exit hyperv_exit(void)
+{
+	vmbus_driver_unregister(&hyperv_hv_driver);
+	pci_unregister_driver(&hyperv_pci_driver);
+}
+
+module_init(hyperv_init);
+module_exit(hyperv_exit);
+
+MODULE_DEVICE_TABLE(pci, hyperv_pci_tbl);
+MODULE_DEVICE_TABLE(vmbus, hyperv_vmbus_tbl);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Deepak Rawat <drawat.floss@gmail.com>");
+MODULE_DESCRIPTION("DRM driver for hyperv synthetic video device");
-- 
2.27.0

[RFC PATCH 2/2] MAINTAINERS: Add maintainer for hyperv video device

[Deepak Rawat]

Maintainer for hyperv synthetic video device.

Signed-off-by: Deepak Rawat <drawat.floss@gmail.com>
---
 MAINTAINERS | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index f437f42b73ad..102f734b99bd 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5316,6 +5316,14 @@ T:	git git://anongit.freedesktop.org/drm/drm-misc
 F:	Documentation/devicetree/bindings/display/himax,hx8357d.txt
 F:	drivers/gpu/drm/tiny/hx8357d.c
 
+DRM DRIVER FOR HYPERV SYNTHETIC VIDEO DEVICE
+M:	Deepak Rawat <drawat.floss@gmail.com>
+L:	linux-hyperv@vger.kernel.org
+L:	dri-devel@lists.freedesktop.org
+S:	Maintained
+T:	git git://anongit.freedesktop.org/drm/drm-misc
+F:	drivers/gpu/drm/tiny/hyperv_drm.c
+
 DRM DRIVER FOR ILITEK ILI9225 PANELS
 M:	David Lechner <david@lechnology.com>
 S:	Maintained
-- 
2.27.0

Re: [RFC PATCH 1/2] drm/hyperv: Add DRM driver for hyperv synthetic video device

[Gerd Hoffmann]

  Hi,

> +/* Should be done only once during init and resume */
> +static int synthvid_update_vram_location(struct hv_device *hdev,
> +					  phys_addr_t vram_pp)
> +{
> +	struct hyperv_device *hv = hv_get_drvdata(hdev);
> +	struct synthvid_msg *msg = (struct synthvid_msg *)hv->init_buf;
> +	unsigned long t;
> +	int ret = 0;
> +
> +	memset(msg, 0, sizeof(struct synthvid_msg));
> +	msg->vid_hdr.type = SYNTHVID_VRAM_LOCATION;
> +	msg->vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
> +		sizeof(struct synthvid_vram_location);
> +	msg->vram.user_ctx = msg->vram.vram_gpa = vram_pp;
> +	msg->vram.is_vram_gpa_specified = 1;
> +	synthvid_send(hdev, msg);

That suggests it is possible to define multiple framebuffers in vram,
then pageflip by setting vram.vram_gpa.  If that is the case I'm
wondering whenever vram helpers are a better fit maybe?  You don't have
to blit each and every display update then.

FYI: cirrus goes the blit route because (a) the amount of vram is very
small so trying to store multiple framebuffers there is out of question,
and (b) cirrus converts formats on the fly to hide some hardware
oddities.

take care,
  Gerd

Re: [RFC PATCH 1/2] drm/hyperv: Add DRM driver for hyperv synthetic video device

[Sam Ravnborg]

Hi Deepak

On Mon, Jun 22, 2020 at 04:06:22AM -0700, Deepak Rawat wrote:
> DRM driver for hyperv synthetic video device, based on hyperv_fb
> framebuffer driver. Also added config option "DRM_HYPERV" to enabled
> this driver.

Just a buch of drive-by comments while browsing the code.
In general code looks good, especialyl for a v1.

There is a few places that triggers warnings with checkpatch --strict
Most looks like things that should be fixed.


	Sam

> 
> Signed-off-by: Deepak Rawat <drawat.floss@gmail.com>
> ---
>  drivers/gpu/drm/tiny/Kconfig      |    9 +
>  drivers/gpu/drm/tiny/Makefile     |    1 +
>  drivers/gpu/drm/tiny/hyperv_drm.c | 1007 +++++++++++++++++++++++++++++
>  3 files changed, 1017 insertions(+)
>  create mode 100644 drivers/gpu/drm/tiny/hyperv_drm.c
> 
> diff --git a/drivers/gpu/drm/tiny/Kconfig b/drivers/gpu/drm/tiny/Kconfig
> index 2b6414f0fa75..e6d53e60a9c2 100644
> --- a/drivers/gpu/drm/tiny/Kconfig
> +++ b/drivers/gpu/drm/tiny/Kconfig
> @@ -28,6 +28,15 @@ config DRM_GM12U320
>  	 This is a KMS driver for projectors which use the GM12U320 chipset
>  	 for video transfer over USB2/3, such as the Acer C120 mini projector.
>  
> +config DRM_HYPERV
> +	tristate "DRM Support for hyperv synthetic video device"
> +	depends on DRM && PCI && MMU && HYPERV
> +	select DRM_KMS_HELPER
> +	select DRM_GEM_SHMEM_HELPER
> +	help
> +	 This is a KMS driver for for hyperv synthetic video device.
> +	 If M is selected the module will be called hyperv_drm.
> +
>  config TINYDRM_HX8357D
>  	tristate "DRM support for HX8357D display panels"
>  	depends on DRM && SPI
> diff --git a/drivers/gpu/drm/tiny/Makefile b/drivers/gpu/drm/tiny/Makefile
> index 6ae4e9e5a35f..837cb2c2637e 100644
> --- a/drivers/gpu/drm/tiny/Makefile
> +++ b/drivers/gpu/drm/tiny/Makefile
> @@ -2,6 +2,7 @@
>  
>  obj-$(CONFIG_DRM_CIRRUS_QEMU)		+= cirrus.o
>  obj-$(CONFIG_DRM_GM12U320)		+= gm12u320.o
> +obj-$(CONFIG_DRM_HYPERV)		+= hyperv_drm.o
>  obj-$(CONFIG_TINYDRM_HX8357D)		+= hx8357d.o
>  obj-$(CONFIG_TINYDRM_ILI9225)		+= ili9225.o
>  obj-$(CONFIG_TINYDRM_ILI9341)		+= ili9341.o
> diff --git a/drivers/gpu/drm/tiny/hyperv_drm.c b/drivers/gpu/drm/tiny/hyperv_drm.c
> new file mode 100644
> index 000000000000..3d020586056e
> --- /dev/null
> +++ b/drivers/gpu/drm/tiny/hyperv_drm.c
> @@ -0,0 +1,1007 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright 2012-2020 Microsoft
> + *
> + * Authors:
> + * Deepak Rawat <drawat.floss@gmail.com>
> + *
> + * Portions of this code is derived from hyperv_fb.c
> + * drivers/video/fbdev/hyperv_fb.c - framebuffer driver for hyperv synthetic
> + * video device.
> + *
> + */
> +
> +#include <linux/console.h>
> +#include <linux/module.h>
> +#include <linux/pci.h>
> +#include <linux/hyperv.h>
Alphabetic order.
> +
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_atomic_state_helper.h>
> +#include <drm/drm_connector.h>
> +#include <drm/drm_damage_helper.h>
> +#include <drm/drm_drv.h>
> +#include <drm/drm_fb_helper.h>
> +#include <drm/drm_file.h>
Needed?

> +#include <drm/drm_format_helper.h>
> +#include <drm/drm_fourcc.h>
> +#include <drm/drm_gem_shmem_helper.h>
> +#include <drm/drm_gem_framebuffer_helper.h>
> +#include <drm/drm_ioctl.h>
> +#include <drm/drm_managed.h>
> +#include <drm/drm_modeset_helper_vtables.h>
> +#include <drm/drm_probe_helper.h>
> +#include <drm/drm_simple_kms_helper.h>

> +
> +#define DRIVER_NAME "hyperv_drm"
> +#define DRIVER_DESC "DRM driver for hyperv synthetic video device"
> +#define DRIVER_DATE "2020"
> +#define DRIVER_MAJOR 1
> +#define DRIVER_MINOR 0
> +
> +#define VMBUS_MAX_PACKET_SIZE 0x4000
> +#define VMBUS_RING_BUFSIZE (256 * 1024)
> +#define VMBUS_VSP_TIMEOUT (10 * HZ)
> +
> +#define PCI_VENDOR_ID_MICROSOFT 0x1414
> +#define PCI_DEVICE_ID_HYPERV_VIDEO 0x5353
> +
> +struct hyperv_device {

This is much more than a device - maybe just name it "struct hv"?

> +	/* drm */
> +	struct drm_device dev;
> +	struct drm_simple_display_pipe pipe;
> +	struct drm_connector connector;
> +
> +	/* mode */
> +	u32 screen_width_max;
> +	u32 screen_height_max;
> +	u32 preferred_width;
> +	u32 preferred_height;
> +	u32 screen_depth;
> +
> +	/* hw */
> +	void __iomem *vram;
> +	unsigned long fb_base;
> +	unsigned long fb_size;
> +	struct completion wait;
> +	u32 synthvid_version;
> +	u32 mmio_megabytes;
> +	bool init_done;
> +
> +	u8 init_buf[VMBUS_MAX_PACKET_SIZE];
> +	u8 recv_buf[VMBUS_MAX_PACKET_SIZE];
> +
> +	struct hv_device *hdev;
> +};
> +
> +#define to_hv(_dev) container_of(_dev, struct hyperv_device, dev)
> +
> +/* ---------------------------------------------------------------------- */
> +/* Hyper-V Synthetic Video Protocol                                       */
> +
> +#define SYNTHVID_VERSION(major, minor) ((minor) << 16 | (major))
> +#define SYNTHVID_VER_GET_MAJOR(ver) (ver & 0x0000ffff)
> +#define SYNTHVID_VER_GET_MINOR(ver) ((ver & 0xffff0000) >> 16)
> +#define SYNTHVID_VERSION_WIN7 SYNTHVID_VERSION(3, 0)
> +#define SYNTHVID_VERSION_WIN8 SYNTHVID_VERSION(3, 2)
> +#define SYNTHVID_VERSION_WIN10 SYNTHVID_VERSION(3, 5)
> +
> +#define SYNTHVID_DEPTH_WIN7 16
> +#define SYNTHVID_DEPTH_WIN8 32
> +#define SYNTHVID_FB_SIZE_WIN7 (4 * 1024 * 1024)
> +#define SYNTHVID_FB_SIZE_WIN8 (8 * 1024 * 1024)
> +#define SYNTHVID_WIDTH_MAX_WIN7 1600
> +#define SYNTHVID_HEIGHT_MAX_WIN7 1200
> +
> +enum pipe_msg_type {
> +	PIPE_MSG_INVALID,
> +	PIPE_MSG_DATA,
> +	PIPE_MSG_MAX
> +};
> +
> +enum synthvid_msg_type {
> +	SYNTHVID_ERROR			= 0,
> +	SYNTHVID_VERSION_REQUEST	= 1,
> +	SYNTHVID_VERSION_RESPONSE	= 2,
> +	SYNTHVID_VRAM_LOCATION		= 3,
> +	SYNTHVID_VRAM_LOCATION_ACK	= 4,
> +	SYNTHVID_SITUATION_UPDATE	= 5,
> +	SYNTHVID_SITUATION_UPDATE_ACK	= 6,
> +	SYNTHVID_POINTER_POSITION	= 7,
> +	SYNTHVID_POINTER_SHAPE		= 8,
> +	SYNTHVID_FEATURE_CHANGE		= 9,
> +	SYNTHVID_DIRT			= 10,
> +	SYNTHVID_RESOLUTION_REQUEST	= 13,
> +	SYNTHVID_RESOLUTION_RESPONSE	= 14,
> +
> +	SYNTHVID_MAX			= 15
> +};
> +
> +struct pipe_msg_hdr {
> +	u32 type;
> +	u32 size; /* size of message after this field */
> +} __packed;
> +
> +struct hvd_screen_info {
> +	u16 width;
> +	u16 height;
> +} __packed;
> +
> +struct synthvid_msg_hdr {
> +	u32 type;
> +	u32 size;  /* size of this header + payload after this field*/
Add space before closing "*/"

I wonder what is the difference between what is considered a message and
what is considered payload in the above comments.
Maybe that just because I do not know this stuff at all and the comment
can be ignored.

> +} __packed;
> +
> +struct synthvid_version_req {
> +	u32 version;
> +} __packed;
> +
> +struct synthvid_version_resp {
> +	u32 version;
> +	u8 is_accepted;
> +	u8 max_video_outputs;
> +} __packed;
> +
> +struct synthvid_vram_location {
> +	u64 user_ctx;
> +	u8 is_vram_gpa_specified;
> +	u64 vram_gpa;
> +} __packed;
Not an alignmnet friendly layout - but I guess the layout is fixed.
Same goes in otther places.

> +
> +struct synthvid_vram_location_ack {
> +	u64 user_ctx;
> +} __packed;
> +
> +struct video_output_situation {
> +	u8 active;
> +	u32 vram_offset;
> +	u8 depth_bits;
> +	u32 width_pixels;
> +	u32 height_pixels;
> +	u32 pitch_bytes;
> +} __packed;
> +
> +struct synthvid_situation_update {
> +	u64 user_ctx;
> +	u8 video_output_count;
> +	struct video_output_situation video_output[1];
> +} __packed;
> +
> +struct synthvid_situation_update_ack {
> +	u64 user_ctx;
> +} __packed;
> +
> +struct synthvid_pointer_position {
> +	u8 is_visible;
> +	u8 video_output;
> +	s32 image_x;
> +	s32 image_y;
> +} __packed;
> +
> +#define SYNTHVID_CURSOR_MAX_X 96
> +#define SYNTHVID_CURSOR_MAX_Y 96
> +#define SYNTHVID_CURSOR_ARGB_PIXEL_SIZE 4
> +#define SYNTHVID_CURSOR_MAX_SIZE (SYNTHVID_CURSOR_MAX_X * \
> +	SYNTHVID_CURSOR_MAX_Y * SYNTHVID_CURSOR_ARGB_PIXEL_SIZE)
> +#define SYNTHVID_CURSOR_COMPLETE (-1)
> +
> +struct synthvid_pointer_shape {
> +	u8 part_idx;
> +	u8 is_argb;
> +	u32 width; /* SYNTHVID_CURSOR_MAX_X at most */
> +	u32 height; /* SYNTHVID_CURSOR_MAX_Y at most */
> +	u32 hot_x; /* hotspot relative to upper-left of pointer image */
> +	u32 hot_y;
> +	u8 data[4];
> +} __packed;
> +
> +struct synthvid_feature_change {
> +	u8 is_dirt_needed;
> +	u8 is_ptr_pos_needed;
> +	u8 is_ptr_shape_needed;
> +	u8 is_situ_needed;
> +} __packed;
> +
> +struct rect {
> +	s32 x1, y1; /* top left corner */
> +	s32 x2, y2; /* bottom right corner, exclusive */
> +} __packed;
> +
> +struct synthvid_dirt {
> +	u8 video_output;
> +	u8 dirt_count;
> +	struct rect rect[1];
> +} __packed;
> +
> +#define SYNTHVID_EDID_BLOCK_SIZE	128
> +#define	SYNTHVID_MAX_RESOLUTION_COUNT	64
> +
> +struct synthvid_supported_resolution_req {
> +	u8 maximum_resolution_count;
> +} __packed;
> +
> +struct synthvid_supported_resolution_resp {
> +	u8 edid_block[SYNTHVID_EDID_BLOCK_SIZE];
> +	u8 resolution_count;
> +	u8 default_resolution_index;
> +	u8 is_standard;
> +	struct hvd_screen_info supported_resolution[SYNTHVID_MAX_RESOLUTION_COUNT];
> +} __packed;
> +
> +struct synthvid_msg {
> +	struct pipe_msg_hdr pipe_hdr;
> +	struct synthvid_msg_hdr vid_hdr;
> +	union {
> +		struct synthvid_version_req ver_req;
> +		struct synthvid_version_resp ver_resp;
> +		struct synthvid_vram_location vram;
> +		struct synthvid_vram_location_ack vram_ack;
> +		struct synthvid_situation_update situ;
> +		struct synthvid_situation_update_ack situ_ack;
> +		struct synthvid_pointer_position ptr_pos;
> +		struct synthvid_pointer_shape ptr_shape;
> +		struct synthvid_feature_change feature_chg;
> +		struct synthvid_dirt dirt;
> +		struct synthvid_supported_resolution_req resolution_req;
> +		struct synthvid_supported_resolution_resp resolution_resp;
> +	};
> +} __packed;
> +
> +static inline bool synthvid_ver_ge(u32 ver1, u32 ver2)
> +{
> +	if (SYNTHVID_VER_GET_MAJOR(ver1) > SYNTHVID_VER_GET_MAJOR(ver2) ||
> +	    (SYNTHVID_VER_GET_MAJOR(ver1) == SYNTHVID_VER_GET_MAJOR(ver2) &&
> +	     SYNTHVID_VER_GET_MINOR(ver1) >= SYNTHVID_VER_GET_MINOR(ver2)))
> +		return true;
> +
> +	return false;
> +}
> +
> +static inline int synthvid_send(struct hv_device *hdev,
> +				struct synthvid_msg *msg)
> +{
> +	static atomic64_t request_id = ATOMIC64_INIT(0);
> +	int ret;
> +
> +	msg->pipe_hdr.type = PIPE_MSG_DATA;
> +	msg->pipe_hdr.size = msg->vid_hdr.size;
> +
> +	ret = vmbus_sendpacket(hdev->channel, msg,
> +			       msg->vid_hdr.size + sizeof(struct pipe_msg_hdr),
> +			       atomic64_inc_return(&request_id),
> +			       VM_PKT_DATA_INBAND, 0);
> +
> +	if (ret)
> +		DRM_ERROR("Unable to send packet via vmbus\n");

Try to use drm_err() and friends, and not DRM_ERR and friends.
DRM_ERR are no logner preferred in drivers.
Goes for all uses of DRM_ERR and friends.

> +
> +	return ret;
> +}
> +
> +static int synthvid_negotiate_ver(struct hv_device *hdev, u32 ver)
> +{
> +	struct hyperv_device *hv = hv_get_drvdata(hdev);
> +	struct synthvid_msg *msg = (struct synthvid_msg *)hv->init_buf;
> +	unsigned long t;
> +	int ret = 0;
> +
> +	memset(msg, 0, sizeof(struct synthvid_msg));
> +	msg->vid_hdr.type = SYNTHVID_VERSION_REQUEST;
> +	msg->vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
> +		sizeof(struct synthvid_version_req);
> +	msg->ver_req.version = ver;
> +	synthvid_send(hdev, msg);
> +
> +	t = wait_for_completion_timeout(&hv->wait, VMBUS_VSP_TIMEOUT);
> +	if (!t) {
> +		DRM_ERROR("Time out on waiting version response\n");
> +		ret = -ETIMEDOUT;
> +		goto out;
> +	}
> +	if (!msg->ver_resp.is_accepted) {
> +		ret = -ENODEV;
> +		goto out;
> +	}
> +
> +	hv->synthvid_version = ver;
> +	DRM_INFO("Synthvid Version major %d, minor %d\n",
> +		 SYNTHVID_VER_GET_MAJOR(ver), SYNTHVID_VER_GET_MINOR(ver));
> +
> +out:
> +	return ret;
> +}
> +
> +/* Should be done only once during init and resume */
> +static int synthvid_update_vram_location(struct hv_device *hdev,
> +					  phys_addr_t vram_pp)
> +{
> +	struct hyperv_device *hv = hv_get_drvdata(hdev);
> +	struct synthvid_msg *msg = (struct synthvid_msg *)hv->init_buf;
> +	unsigned long t;
> +	int ret = 0;
> +
> +	memset(msg, 0, sizeof(struct synthvid_msg));
> +	msg->vid_hdr.type = SYNTHVID_VRAM_LOCATION;
> +	msg->vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
> +		sizeof(struct synthvid_vram_location);
> +	msg->vram.user_ctx = msg->vram.vram_gpa = vram_pp;
> +	msg->vram.is_vram_gpa_specified = 1;
> +	synthvid_send(hdev, msg);
> +
> +	t = wait_for_completion_timeout(&hv->wait, VMBUS_VSP_TIMEOUT);
> +	if (!t) {
> +		DRM_ERROR("Time out on waiting vram location ack\n");
> +		ret = -ETIMEDOUT;
> +		goto out;
> +	}
> +	if (msg->vram_ack.user_ctx != vram_pp) {
> +		DRM_ERROR("Unable to set VRAM location\n");
> +		ret = -ENODEV;
> +	}
> +
> +out:
> +	return ret;
> +}
> +
> +static int synthvid_update_situation(struct hv_device *hdev, u8 active, u32 bpp,
> +				     u32 w, u32 h, u32 pitch)
> +{
> +	struct synthvid_msg msg;

Sometimes synthvid_msg is hv->init_buf.
Sometimes a local variable.
I wonder why there is a difference.

> +
> +	memset(&msg, 0, sizeof(struct synthvid_msg));
> +
> +	msg.vid_hdr.type = SYNTHVID_SITUATION_UPDATE;
> +	msg.vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
> +		sizeof(struct synthvid_situation_update);
> +	msg.situ.user_ctx = 0;
> +	msg.situ.video_output_count = 1;
> +	msg.situ.video_output[0].active = active;
> +	/* vram_offset should always be 0 */
> +	msg.situ.video_output[0].vram_offset = 0;
> +	msg.situ.video_output[0].depth_bits = bpp;
> +	msg.situ.video_output[0].width_pixels = w;
> +	msg.situ.video_output[0].height_pixels = h;
> +	msg.situ.video_output[0].pitch_bytes = pitch;
> +
> +	synthvid_send(hdev, &msg);
> +
> +	return 0;
> +}
> +
> +static int synthvid_update_dirt(struct hv_device *hdev, struct drm_rect *rect)
> +{
> +	struct synthvid_msg msg;
> +
> +	memset(&msg, 0, sizeof(struct synthvid_msg));
> +
> +	msg.vid_hdr.type = SYNTHVID_DIRT;
> +	msg.vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
> +		sizeof(struct synthvid_dirt);
> +	msg.dirt.video_output = 0;
> +	msg.dirt.dirt_count = 1;
> +	msg.dirt.rect[0].x1 = rect->x1;
> +	msg.dirt.rect[0].y1 = rect->y1;
> +	msg.dirt.rect[0].x2 = rect->x2;
> +	msg.dirt.rect[0].y2 = rect->y2;
> +
> +	synthvid_send(hdev, &msg);
> +
> +	return 0;
> +}
> +
> +static int synthvid_get_supported_resolution(struct hv_device *hdev)
> +{
> +	struct hyperv_device *hv = hv_get_drvdata(hdev);
> +	struct synthvid_msg *msg = (struct synthvid_msg *)hv->init_buf;
> +	unsigned long t;
> +	int ret = 0;
> +	u8 index;
> +	int i;
> +
> +	memset(msg, 0, sizeof(struct synthvid_msg));
> +	msg->vid_hdr.type = SYNTHVID_RESOLUTION_REQUEST;
> +	msg->vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
> +		sizeof(struct synthvid_supported_resolution_req);
> +	msg->resolution_req.maximum_resolution_count =
> +		SYNTHVID_MAX_RESOLUTION_COUNT;
> +	synthvid_send(hdev, msg);
> +
> +	t = wait_for_completion_timeout(&hv->wait, VMBUS_VSP_TIMEOUT);
> +	if (!t) {
> +		DRM_ERROR("Time out on waiting resolution response\n");
> +		ret = -ETIMEDOUT;
> +		goto out;
> +	}
> +
> +	if (msg->resolution_resp.resolution_count == 0) {
> +		DRM_ERROR("No supported resolutions\n");
> +		ret = -ENODEV;
> +		goto out;
> +	}
> +
> +	index = msg->resolution_resp.default_resolution_index;
> +	if (index >= msg->resolution_resp.resolution_count) {
> +		DRM_ERROR("Invalid resolution index: %d\n", index);
> +		ret = -ENODEV;
> +		goto out;
> +	}
> +
> +	for (i = 0; i < msg->resolution_resp.resolution_count; i++) {
> +		hv->screen_width_max = max_t(u32, hv->screen_width_max,
> +			msg->resolution_resp.supported_resolution[i].width);
> +		hv->screen_height_max = max_t(u32, hv->screen_height_max,
> +			msg->resolution_resp.supported_resolution[i].height);
> +	}
> +
> +	hv->preferred_width =
> +		msg->resolution_resp.supported_resolution[index].width;
> +	hv->preferred_height =
> +		msg->resolution_resp.supported_resolution[index].height;
> +
> +out:
> +	return ret;
> +}
> +
> +/* Actions on received messages from host */
> +static void synthvid_recv_sub(struct hv_device *hdev)
> +{
> +	struct hyperv_device *hv = hv_get_drvdata(hdev);
> +	struct synthvid_msg *msg;
> +
> +	if (!hv)
> +		return;
> +
> +	msg = (struct synthvid_msg *)hv->recv_buf;
> +
> +	/* Complete the wait event */
> +	if (msg->vid_hdr.type == SYNTHVID_VERSION_RESPONSE ||
> +	    msg->vid_hdr.type == SYNTHVID_RESOLUTION_RESPONSE ||
> +	    msg->vid_hdr.type == SYNTHVID_VRAM_LOCATION_ACK) {
> +		memcpy(hv->init_buf, msg, VMBUS_MAX_PACKET_SIZE);
> +		complete(&hv->wait);
> +		return;
> +	}
> +}
> +
> +static void synthvid_receive(void *ctx)
> +{
> +	struct hv_device *hdev = ctx;
> +	struct hyperv_device *hv = hv_get_drvdata(hdev);
> +	struct synthvid_msg *recv_buf;
> +	u32 bytes_recvd;
> +	u64 req_id;
> +	int ret;
> +
> +	if (!hv)
> +		return;
> +
> +	recv_buf = (struct synthvid_msg *)hv->recv_buf;
> +
> +	do {
> +		ret = vmbus_recvpacket(hdev->channel, recv_buf,
> +				       VMBUS_MAX_PACKET_SIZE,
> +				       &bytes_recvd, &req_id);
> +		if (bytes_recvd > 0 &&
> +		    recv_buf->pipe_hdr.type == PIPE_MSG_DATA)
> +			synthvid_recv_sub(hdev);
> +	} while (bytes_recvd > 0 && ret == 0);
> +}
> +
> +static int synthvid_connect_vsp(struct hv_device *hdev)
> +{
> +	struct hyperv_device *hv = hv_get_drvdata(hdev);
> +	int ret;
> +
> +	ret = vmbus_open(hdev->channel, VMBUS_RING_BUFSIZE, VMBUS_RING_BUFSIZE,
> +			 NULL, 0, synthvid_receive, hdev);
> +	if (ret) {
> +		DRM_ERROR("Unable to open vmbus channel\n");
> +		return ret;
> +	}
> +
> +	/* Negotiate the protocol version with host */
> +	switch (vmbus_proto_version) {
> +	case VERSION_WIN10:
> +	case VERSION_WIN10_V5:
> +		ret = synthvid_negotiate_ver(hdev, SYNTHVID_VERSION_WIN10);
> +		if (!ret)
> +			break;
> +		fallthrough;
> +	case VERSION_WIN8:
> +	case VERSION_WIN8_1:
> +		ret = synthvid_negotiate_ver(hdev, SYNTHVID_VERSION_WIN8);
> +		if (!ret)
> +			break;
> +		fallthrough;
> +	case VERSION_WS2008:
> +	case VERSION_WIN7:
> +		ret = synthvid_negotiate_ver(hdev, SYNTHVID_VERSION_WIN7);
> +		break;
> +	default:
> +		ret = synthvid_negotiate_ver(hdev, SYNTHVID_VERSION_WIN10);
> +		break;
> +	}
> +
> +	if (ret) {
> +		DRM_ERROR("Synthetic video device version not accepted\n");
Print error code?

> +		goto error;
> +	}
> +
> +	if (hv->synthvid_version == SYNTHVID_VERSION_WIN7)
> +		hv->screen_depth = SYNTHVID_DEPTH_WIN7;
> +	else
> +		hv->screen_depth = SYNTHVID_DEPTH_WIN8;
> +
> +	if (synthvid_ver_ge(hv->synthvid_version, SYNTHVID_VERSION_WIN10)) {
> +		ret = synthvid_get_supported_resolution(hdev);
> +		if (ret)
> +			DRM_ERROR("Failed to get supported resolution from host, use default\n");
> +	} else {
> +		hv->screen_width_max = SYNTHVID_WIDTH_MAX_WIN7;
> +		hv->screen_height_max = SYNTHVID_HEIGHT_MAX_WIN7;
> +	}
> +
> +	hv->mmio_megabytes = hdev->channel->offermsg.offer.mmio_megabytes;
> +
> +	return 0;
> +
> +error:
> +	vmbus_close(hdev->channel);
> +	return ret;
> +}
> +
> +/* ---------------------------------------------------------------------- */
> +/* VRAM blit                                                              */
> +
> +static int hyperv_blit_to_vram_rect(struct drm_framebuffer *fb,
> +				    struct drm_rect *rect)
> +{
> +	struct hyperv_device *hv = to_hv(fb->dev);
> +	void *vmap;
> +	int idx, ret;
> +
> +	ret = -ENODEV;
> +	if (!drm_dev_enter(&hv->dev, &idx))
> +		goto out;
> +
> +	ret = -ENOMEM;
> +	vmap = drm_gem_shmem_vmap(fb->obj[0]);
> +	if (!vmap)
> +		goto out_dev_exit;
> +
> +	drm_fb_memcpy_dstclip(hv->vram, vmap, fb, rect);
> +	drm_gem_shmem_vunmap(fb->obj[0], vmap);
> +	ret = 0;
> +
> +out_dev_exit:
> +	drm_dev_exit(idx);
> +out:
> +	return ret;
> +}
> +
> +static int hyperv_blit_to_vram_fullscreen(struct drm_framebuffer *fb)
> +{
> +	struct drm_rect fullscreen = {
> +		.x1 = 0,
> +		.x2 = fb->width,
> +		.y1 = 0,
> +		.y2 = fb->height,
> +	};
> +	return hyperv_blit_to_vram_rect(fb, &fullscreen);
> +}
> +
> +/* ---------------------------------------------------------------------- */
> +/* connector                                                              */
> +
> +static int hyperv_connector_get_modes(struct drm_connector *connector)
> +{
> +	struct hyperv_device *hv = to_hv(connector->dev);
> +	int count;
> +
> +	count = drm_add_modes_noedid(connector,
> +				     connector->dev->mode_config.max_width,
> +				     connector->dev->mode_config.max_height);
> +	drm_set_preferred_mode(connector, hv->preferred_width,
> +			       hv->preferred_height);
> +
> +	return count;
> +}
> +
> +static const struct drm_connector_helper_funcs hyperv_connector_helper_funcs = {
> +	.get_modes = hyperv_connector_get_modes,
> +};
> +
> +static const struct drm_connector_funcs hyperv_connector_funcs = {
> +	.fill_modes = drm_helper_probe_single_connector_modes,
> +	.destroy = drm_connector_cleanup,
> +	.reset = drm_atomic_helper_connector_reset,
> +	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
> +	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> +};
> +
> +static int hyperv_conn_init(struct hyperv_device *hv)
> +{
> +	drm_connector_helper_add(&hv->connector, &hyperv_connector_helper_funcs);
> +	return drm_connector_init(&hv->dev, &hv->connector,
> +				  &hyperv_connector_funcs,
> +				  DRM_MODE_CONNECTOR_VGA);
> +
> +}
> +
> +/* ---------------------------------------------------------------------- */
> +/* display pipe                                                           */
> +
> +static int hyperv_check_size(struct hyperv_device *hv, int w, int h,
> +			     struct drm_framebuffer *fb)
> +{
> +	u32 pitch = w * (hv->screen_depth/8);
> +
> +	if (fb)
> +		pitch = fb->pitches[0];
> +
> +	if (pitch * h > hv->fb_size)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static enum drm_mode_status
> +hyperv_pipe_mode_valid(struct drm_simple_display_pipe *pipe,
> +		       const struct drm_display_mode *mode)
> +{
> +	struct hyperv_device *hv = to_hv(pipe->crtc.dev);
> +
> +	if (hyperv_check_size(hv, mode->hdisplay, mode->vdisplay, NULL))
> +		return MODE_BAD;
> +
> +	return MODE_OK;
> +}
> +
> +static void hyperv_pipe_enable(struct drm_simple_display_pipe *pipe,
> +			       struct drm_crtc_state *crtc_state,
> +			       struct drm_plane_state *plane_state)
> +{
> +	struct hyperv_device *hv = to_hv(pipe->crtc.dev);
> +
> +	synthvid_update_situation(hv->hdev, 1,  hv->screen_depth,
> +				  crtc_state->mode.hdisplay,
> +				  crtc_state->mode.vdisplay,
> +				  plane_state->fb->pitches[0]);
> +	hyperv_blit_to_vram_fullscreen(plane_state->fb);
> +}
> +
> +static void hyperv_pipe_update(struct drm_simple_display_pipe *pipe,
> +			      struct drm_plane_state *old_state)
> +{
> +	struct hyperv_device *hv = to_hv(pipe->crtc.dev);
> +	struct drm_plane_state *state = pipe->plane.state;
> +	struct drm_rect rect;
> +
> +	if (drm_atomic_helper_damage_merged(old_state, state, &rect)) {
> +		hyperv_blit_to_vram_rect(state->fb, &rect);
> +		synthvid_update_dirt(hv->hdev, &rect);
> +	}
> +}
> +
> +static const struct drm_simple_display_pipe_funcs hyperv_pipe_funcs = {
> +	.mode_valid = hyperv_pipe_mode_valid,
> +	.enable	= hyperv_pipe_enable,
> +	.update	= hyperv_pipe_update,
> +};
> +
> +static const uint32_t hyperv_formats[] = {
> +	DRM_FORMAT_XRGB8888,
> +};
> +
> +static const uint64_t hyperv_modifiers[] = {
> +	DRM_FORMAT_MOD_LINEAR,
> +	DRM_FORMAT_MOD_INVALID
> +};
> +
> +static int hyperv_pipe_init(struct hyperv_device *hv)
> +{
> +	int ret;
> +
> +	ret = drm_simple_display_pipe_init(&hv->dev,
> +					   &hv->pipe,
> +					   &hyperv_pipe_funcs,
> +					   hyperv_formats,
> +					   ARRAY_SIZE(hyperv_formats),
> +					   NULL,
> +					   &hv->connector);
> +
> +	drm_plane_enable_fb_damage_clips(&(hv->pipe.plane));
> +
> +	return ret;
> +}
> +
> +/* ---------------------------------------------------------------------- */
> +/* framebuffers & mode config                                             */
> +
> +static struct drm_framebuffer*
> +hyperv_fb_create(struct drm_device *dev, struct drm_file *file_priv,
> +		 const struct drm_mode_fb_cmd2 *mode_cmd)
> +{
> +	struct hyperv_device *hv = to_hv(dev);
> +
> +	if (mode_cmd->pixel_format != DRM_FORMAT_XRGB8888)
> +		return ERR_PTR(-EINVAL);
> +
> +	if (mode_cmd->pitches[0] * mode_cmd->height > hv->fb_size)
> +		return ERR_PTR(-EINVAL);
> +
> +	return drm_gem_fb_create_with_dirty(dev, file_priv, mode_cmd);
> +}
> +
> +static const struct drm_mode_config_funcs hyperv_mode_config_funcs = {
> +	.fb_create = hyperv_fb_create,
> +	.atomic_check = drm_atomic_helper_check,
> +	.atomic_commit = drm_atomic_helper_commit,
> +};
> +
> +static int hyperv_mode_config_init(struct hyperv_device *hv)
> +{
> +	struct drm_device *dev = &hv->dev;
> +	int ret;
> +
> +	ret = drmm_mode_config_init(dev);
> +	if (ret)
> +		return ret;
> +
> +	dev->mode_config.min_width = 0;
> +	dev->mode_config.min_height = 0;
> +	dev->mode_config.max_width = hv->screen_width_max;
> +	dev->mode_config.max_height = hv->screen_height_max;
> +
> +	dev->mode_config.preferred_depth = hv->screen_depth;
> +	dev->mode_config.prefer_shadow = 0;
> +
> +	dev->mode_config.funcs = &hyperv_mode_config_funcs;
> +
> +	return 0;
> +}
> +
> +/* ---------------------------------------------------------------------- */
> +/* DRM                                                                    */
> +
> +DEFINE_DRM_GEM_FOPS(hv_fops);
> +
> +static struct drm_driver hyperv_driver = {
> +	.driver_features = DRIVER_MODESET | DRIVER_GEM | DRIVER_ATOMIC,
> +
> +	.name		 = DRIVER_NAME,
> +	.desc		 = DRIVER_DESC,
> +	.date		 = DRIVER_DATE,
> +	.major		 = DRIVER_MAJOR,
> +	.minor		 = DRIVER_MINOR,
> +
> +	.fops		 = &hv_fops,
> +	DRM_GEM_SHMEM_DRIVER_OPS,
> +};
> +
> +/* ---------------------------------------------------------------------- */
> +/* pci/vmbus interface                                                    */
> +
> +static int hyperv_pci_probe(struct pci_dev *pdev,
> +			    const struct pci_device_id *ent)
> +{
> +	return 0;
> +}
> +
> +static void hyperv_pci_remove(struct pci_dev *pdev)
> +{
> +}
> +
> +static const struct pci_device_id hyperv_pci_tbl[] = {
> +	{
> +		.vendor = PCI_VENDOR_ID_MICROSOFT,
> +		.device = PCI_DEVICE_ID_HYPERV_VIDEO,
> +	},
> +	{ /* end of list */ }
> +};
> +
> +static struct pci_driver hyperv_pci_driver = {
> +	.name =		KBUILD_MODNAME,
> +	.id_table =	hyperv_pci_tbl,
> +	.probe =	hyperv_pci_probe,
> +	.remove =	hyperv_pci_remove,
> +};
> +
> +static int hyperv_vmbus_probe(struct hv_device *hdev,
> +			      const struct hv_vmbus_device_id *dev_id)
> +{
> +	struct hyperv_device *hv;
> +	struct drm_device *dev;
> +	struct pci_dev *pdev;
> +	int ret;
> +
> +	hv = devm_drm_dev_alloc(&hdev->device, &hyperv_driver,
> +				struct hyperv_device, dev);
> +	if (IS_ERR(hv))
> +		return PTR_ERR(hv);
> +
> +	dev = &hv->dev;
> +	init_completion(&hv->wait);
> +	hv_set_drvdata(hdev, hv);
> +	hv->hdev = hdev;
> +
> +	pdev = pci_get_device(PCI_VENDOR_ID_MICROSOFT,
> +			      PCI_DEVICE_ID_HYPERV_VIDEO, NULL);
> +	if (!pdev) {
> +		DRM_ERROR("Unable to find PCI Hyper-V video\n");
> +		return -ENODEV;
> +	}
> +
> +	ret = drm_fb_helper_remove_conflicting_pci_framebuffers(pdev, "hypervdrmfb");
> +	if (ret) {
> +		DRM_ERROR("Not able to remove boot fb\n");
> +		goto error;
> +	}
> +
> +	if (pci_request_region(pdev, 0, DRIVER_NAME) != 0)
> +		DRM_WARN("Cannot request framebuffer, boot fb still active?\n");
devm variant?

> +
> +	if ((pdev->resource[0].flags & IORESOURCE_MEM) == 0) {
> +		DRM_ERROR("Resource at bar 0 is not IORESOURCE_MEM\n");
> +		ret = -ENODEV;
> +		goto error;
> +	}
> +
> +	hv->fb_base = pci_resource_start(pdev, 0);
> +	hv->fb_size = pci_resource_len(pdev, 0);
> +	if (hv->fb_base == 0) {
> +		DRM_ERROR("Resource not available\n");
> +		ret = -ENODEV;
> +		goto error;
> +	}
> +
> +	/* Get the actual VRAM size from the device */
> +	ret = synthvid_connect_vsp(hdev);
> +	if (ret) {
> +		DRM_ERROR("Failed to connect to vmbus\n");
> +		goto error;
> +	}
> +
> +	hv->fb_size = min(hv->fb_size,
> +			  (unsigned long)(hv->mmio_megabytes * 1024 * 1024));
> +	hv->vram = devm_ioremap(&pdev->dev, hv->fb_base, hv->fb_size);
> +	if (hv->vram == NULL) {
> +		DRM_ERROR("Failed to map vram\n");
> +		ret = -ENOMEM;
> +		goto error1;
> +	}
> +
> +	/*
> +	 * Failing to update vram location is not fatal. Device will update
> +	 * dirty area till preferred resolution only.
> +	 */
> +	ret = synthvid_update_vram_location(hdev, hv->fb_base);
> +	if (ret)
> +		DRM_WARN("Failed to update vram location.\n");
> +
> +	ret = hyperv_mode_config_init(hv);
> +	if (ret) {
> +		DRM_ERROR("Failed to initialized mode setting\n");
> +		goto error1;
> +	}
> +
> +	ret = hyperv_conn_init(hv);
> +	if (ret) {
> +		DRM_ERROR("Failed to initialized connector\n");
> +		goto error1;
> +	}
> +
> +	ret = hyperv_pipe_init(hv);
> +	if (ret) {
> +		DRM_ERROR("Failed to initialized pipe\n");
> +		goto error1;
> +	}
> +
> +	drm_mode_config_reset(dev);
> +
> +	ret = drm_dev_register(dev, 0);
> +	if (ret) {
> +		DRM_ERROR("Failed to register drm driver\n");
> +		goto error1;
> +	}
> +
> +	drm_fbdev_generic_setup(dev, dev->mode_config.preferred_depth);
> +
> +	pci_dev_put(pdev);
> +	return 0;
> +
> +error1:
> +	vmbus_close(hdev->channel);
> +error:
> +	hv_set_drvdata(hdev, NULL);
> +	pci_dev_put(pdev);
> +	return ret;
> +}
> +
> +static int hyperv_vmbus_remove(struct hv_device *hdev)
> +{
> +	struct drm_device *dev = hv_get_drvdata(hdev);
> +
> +	drm_dev_unplug(dev);
> +	drm_atomic_helper_shutdown(dev);
> +	vmbus_close(hdev->channel);
> +	hv_set_drvdata(hdev, NULL);
> +
> +	return 0;
> +}
> +
> +static int hyperv_vmbus_suspend(struct hv_device *hdev)
> +{
> +	struct drm_device *dev = hv_get_drvdata(hdev);
> +	int ret;
> +
> +	ret = drm_mode_config_helper_suspend(dev);
> +
> +	vmbus_close(hdev->channel);
> +
> +	return ret;
> +}
> +
> +static int hyperv_vmbus_resume(struct hv_device *hdev)
> +{
> +	struct drm_device *dev = hv_get_drvdata(hdev);
> +	int ret;
> +
> +	ret = synthvid_connect_vsp(hdev);
> +	if (ret)
> +		return ret;
> +
> +	return drm_mode_config_helper_resume(dev);
> +}
> +
> +static const struct hv_vmbus_device_id hyperv_vmbus_tbl[] = {
> +	/* Synthetic Video Device GUID */
> +	{HV_SYNTHVID_GUID},
> +	{}
> +};
> +
> +static struct hv_driver hyperv_hv_driver = {
> +	.name = KBUILD_MODNAME,
> +	.id_table = hyperv_vmbus_tbl,
> +	.probe = hyperv_vmbus_probe,
> +	.remove = hyperv_vmbus_remove,
> +	.suspend = hyperv_vmbus_suspend,
> +	.resume = hyperv_vmbus_resume,
> +	.driver = {
> +		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
> +	},
> +};
> +
> +/* ---------------------------------------------------------------------- */
> +/* module init/exit                                                       */
> +
> +static int __init hyperv_init(void)
> +{
> +	int ret;
> +
> +	ret = pci_register_driver(&hyperv_pci_driver);
> +	if (ret != 0) {
> +		DRM_ERROR("Failed to register pci driver\n");
> +		return ret;
> +	}
> +
> +	ret = vmbus_driver_register(&hyperv_hv_driver);
> +	if (ret != 0)
> +		DRM_ERROR("Failed to register vmbus driver\n");
> +
> +	return ret;
> +}
> +
> +static void __exit hyperv_exit(void)
> +{
> +	vmbus_driver_unregister(&hyperv_hv_driver);
> +	pci_unregister_driver(&hyperv_pci_driver);
> +}
> +
> +module_init(hyperv_init);
> +module_exit(hyperv_exit);
> +
> +MODULE_DEVICE_TABLE(pci, hyperv_pci_tbl);
> +MODULE_DEVICE_TABLE(vmbus, hyperv_vmbus_tbl);
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Deepak Rawat <drawat.floss@gmail.com>");
> +MODULE_DESCRIPTION("DRM driver for hyperv synthetic video device");
> -- 
> 2.27.0
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

Re: [RFC PATCH 1/2] drm/hyperv: Add DRM driver for hyperv synthetic video device

[Deepak Rawat]

On Mon, 2020-06-22 at 14:46 +0200, Gerd Hoffmann wrote:
>   Hi,
> 
> > +/* Should be done only once during init and resume */
> > +static int synthvid_update_vram_location(struct hv_device *hdev,
> > +					  phys_addr_t vram_pp)
> > +{
> > +	struct hyperv_device *hv = hv_get_drvdata(hdev);
> > +	struct synthvid_msg *msg = (struct synthvid_msg *)hv->init_buf;
> > +	unsigned long t;
> > +	int ret = 0;
> > +
> > +	memset(msg, 0, sizeof(struct synthvid_msg));
> > +	msg->vid_hdr.type = SYNTHVID_VRAM_LOCATION;
> > +	msg->vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
> > +		sizeof(struct synthvid_vram_location);
> > +	msg->vram.user_ctx = msg->vram.vram_gpa = vram_pp;
> > +	msg->vram.is_vram_gpa_specified = 1;
> > +	synthvid_send(hdev, msg);
> 
> That suggests it is possible to define multiple framebuffers in vram,
> then pageflip by setting vram.vram_gpa.  If that is the case I'm
> wondering whenever vram helpers are a better fit maybe?  You don't
> have
> to blit each and every display update then.

Thanks for the review. Unfortunately only the first vmbus message take
effect and subsequent calls are ignored. I originally implemented using
vram helpers but I figured out calling this vmbus message again won't
change the vram location.

> 
> FYI: cirrus goes the blit route because (a) the amount of vram is
> very
> small so trying to store multiple framebuffers there is out of
> question,
> and (b) cirrus converts formats on the fly to hide some hardware
> oddities.
> 
> take care,
>   Gerd
> 

Re: [RFC PATCH 1/2] drm/hyperv: Add DRM driver for hyperv synthetic video device

[Deepak Rawat]

> 
> Just a buch of drive-by comments while browsing the code.
> In general code looks good, especialyl for a v1.
> 
> There is a few places that triggers warnings with checkpatch --strict
> Most looks like things that should be fixed.
> 
> 

Thanks Sam for the review. Will take care of the suggestions in next
iteration.

Response inlined below:


> > +struct pipe_msg_hdr {
> > +	u32 type;
> > +	u32 size; /* size of message after this field */
> > +} __packed;
> > +
> > +struct hvd_screen_info {
> > +	u16 width;
> > +	u16 height;
> > +} __packed;
> > +
> > +struct synthvid_msg_hdr {
> > +	u32 type;
> > +	u32 size;  /* size of this header + payload after this field*/
> Add space before closing "*/"
> 
> I wonder what is the difference between what is considered a message
> and
> what is considered payload in the above comments.
> Maybe that just because I do not know this stuff at all and the
> comment
> can be ignored.

message = struct pipe_msg_hdr + struct synthvid_msg_hdr + payload

Will try to make it more clear.

> 
> > +} __packed;
> > +
> > +struct synthvid_version_req {
> > +	u32 version;
> > +} __packed;
> > +
> > +struct synthvid_version_resp {
> > +	u32 version;
> > +	u8 is_accepted;
> > +	u8 max_video_outputs;
> > +} __packed;
> > +
> > +struct synthvid_vram_location {
> > +	u64 user_ctx;
> > +	u8 is_vram_gpa_specified;
> > +	u64 vram_gpa;
> > +} __packed;
> Not an alignmnet friendly layout - but I guess the layout is fixed.
> Same goes in otther places.

Yes nothing can be done for this.


> 
> > +static int synthvid_update_situation(struct hv_device *hdev, u8
> > active, u32 bpp,
> > +				     u32 w, u32 h, u32 pitch)
> > +{
> > +	struct synthvid_msg msg;
> 
> Sometimes synthvid_msg is hv->init_buf.
> Sometimes a local variable.
> I wonder why there is a difference.

When a reply is expected, hv->init_buf should be used, though I haven't
verified this. Just kept the same logic as in framebuffer driver.

RE: [RFC PATCH 1/2] drm/hyperv: Add DRM driver for hyperv synthetic video device

[Dexuan Cui]

> From: linux-hyperv-owner@vger.kernel.org
> <linux-hyperv-owner@vger.kernel.org> On Behalf Of Deepak Rawat
> Sent: Monday, June 22, 2020 4:06 AM
> 
> DRM driver for hyperv synthetic video device, based on hyperv_fb
> framebuffer driver. Also added config option "DRM_HYPERV" to enabled
> this driver.

Hi Deepak,
I had a quick look and overall the patch as v1 looks good to me. 

Some quick comments:
1. hyperv_vmbus_probe() assumes the existence of the PCI device, which
is not true in a Hyper-V Generation-2 VM.

2. It looks some other functionality in the hyperv_fb driver has not been
implemented in this new driver either, e.g. the handling of the
SYNTHVID_FEATURE_CHANGE msg.

Thanks,
-- Dexuan

Re: [RFC PATCH 1/2] drm/hyperv: Add DRM driver for hyperv synthetic video device

[Deepak Rawat]

On Tue, 2020-06-23 at 02:31 +0000, Dexuan Cui wrote:
> > From: linux-hyperv-owner@vger.kernel.org
> > <linux-hyperv-owner@vger.kernel.org> On Behalf Of Deepak Rawat
> > Sent: Monday, June 22, 2020 4:06 AM
> > 
> > DRM driver for hyperv synthetic video device, based on hyperv_fb
> > framebuffer driver. Also added config option "DRM_HYPERV" to
> > enabled
> > this driver.
> 
> Hi Deepak,
> I had a quick look and overall the patch as v1 looks good to me. 

Thanks Dexuan for the review.

> 
> Some quick comments:
> 1. hyperv_vmbus_probe() assumes the existence of the PCI device,
> which
> is not true in a Hyper-V Generation-2 VM.

I guess that mean for Gen-2 VM need to rely on vmbus_allocate_mmio to
get the VRAM memory? From what I understand the pci interface anyway
maps to vmbus.

> 
> 2. It looks some other functionality in the hyperv_fb driver has not
> been
> implemented in this new driver either, e.g. the handling of the
> SYNTHVID_FEATURE_CHANGE msg.

I deliberately left this and things seems to work without this, maybe I
need to do more testing. I don't really understand the use-case
of SYNTHVID_FEATURE_CHANGE. I observed this message was received just
after vmbus connect and DRM is not yet initialized so no point updating
the situation. Even otherwise situation (mode, damage, etc.) is
triggered from user-space, not sure what to update. But will definitely
clarify on this.

> 
> Thanks,
> -- Dexuan

Re: [RFC PATCH 1/2] drm/hyperv: Add DRM driver for hyperv synthetic video device

[Thomas Zimmermann]

[-- Attachment #1.1: Type: text/plain, Size: 35192 bytes --]

Hi Deepak

I did not receive you pat series, so I can only comment on Sam's reply.
See below for some points.

Am 22.06.20 um 17:19 schrieb Sam Ravnborg:
> Hi Deepak
> 
> On Mon, Jun 22, 2020 at 04:06:22AM -0700, Deepak Rawat wrote:
>> DRM driver for hyperv synthetic video device, based on hyperv_fb
>> framebuffer driver. Also added config option "DRM_HYPERV" to enabled
>> this driver.
> 
> Just a buch of drive-by comments while browsing the code.
> In general code looks good, especialyl for a v1.
> 
> There is a few places that triggers warnings with checkpatch --strict
> Most looks like things that should be fixed.
> 
> 
> 	Sam
> 
>>
>> Signed-off-by: Deepak Rawat <drawat.floss@gmail.com>
>> ---
>>  drivers/gpu/drm/tiny/Kconfig      |    9 +
>>  drivers/gpu/drm/tiny/Makefile     |    1 +
>>  drivers/gpu/drm/tiny/hyperv_drm.c | 1007 +++++++++++++++++++++++++++++
>>  3 files changed, 1017 insertions(+)
>>  create mode 100644 drivers/gpu/drm/tiny/hyperv_drm.c
>>
>> diff --git a/drivers/gpu/drm/tiny/Kconfig b/drivers/gpu/drm/tiny/Kconfig
>> index 2b6414f0fa75..e6d53e60a9c2 100644
>> --- a/drivers/gpu/drm/tiny/Kconfig
>> +++ b/drivers/gpu/drm/tiny/Kconfig
>> @@ -28,6 +28,15 @@ config DRM_GM12U320
>>  	 This is a KMS driver for projectors which use the GM12U320 chipset
>>  	 for video transfer over USB2/3, such as the Acer C120 mini projector.
>>  
>> +config DRM_HYPERV
>> +	tristate "DRM Support for hyperv synthetic video device"
>> +	depends on DRM && PCI && MMU && HYPERV
>> +	select DRM_KMS_HELPER
>> +	select DRM_GEM_SHMEM_HELPER
>> +	help
>> +	 This is a KMS driver for for hyperv synthetic video device.
>> +	 If M is selected the module will be called hyperv_drm.
>> +
>>  config TINYDRM_HX8357D
>>  	tristate "DRM support for HX8357D display panels"
>>  	depends on DRM && SPI
>> diff --git a/drivers/gpu/drm/tiny/Makefile b/drivers/gpu/drm/tiny/Makefile
>> index 6ae4e9e5a35f..837cb2c2637e 100644
>> --- a/drivers/gpu/drm/tiny/Makefile
>> +++ b/drivers/gpu/drm/tiny/Makefile
>> @@ -2,6 +2,7 @@
>>  
>>  obj-$(CONFIG_DRM_CIRRUS_QEMU)		+= cirrus.o
>>  obj-$(CONFIG_DRM_GM12U320)		+= gm12u320.o
>> +obj-$(CONFIG_DRM_HYPERV)		+= hyperv_drm.o
>>  obj-$(CONFIG_TINYDRM_HX8357D)		+= hx8357d.o
>>  obj-$(CONFIG_TINYDRM_ILI9225)		+= ili9225.o
>>  obj-$(CONFIG_TINYDRM_ILI9341)		+= ili9341.o
>> diff --git a/drivers/gpu/drm/tiny/hyperv_drm.c b/drivers/gpu/drm/tiny/hyperv_drm.c
>> new file mode 100644
>> index 000000000000..3d020586056e
>> --- /dev/null
>> +++ b/drivers/gpu/drm/tiny/hyperv_drm.c
>> @@ -0,0 +1,1007 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright 2012-2020 Microsoft
>> + *
>> + * Authors:
>> + * Deepak Rawat <drawat.floss@gmail.com>
>> + *
>> + * Portions of this code is derived from hyperv_fb.c
>> + * drivers/video/fbdev/hyperv_fb.c - framebuffer driver for hyperv synthetic
>> + * video device.
>> + *
>> + */
>> +
>> +#include <linux/console.h>
>> +#include <linux/module.h>
>> +#include <linux/pci.h>
>> +#include <linux/hyperv.h>
> Alphabetic order.
>> +
>> +#include <drm/drm_atomic_helper.h>
>> +#include <drm/drm_atomic_state_helper.h>
>> +#include <drm/drm_connector.h>
>> +#include <drm/drm_damage_helper.h>
>> +#include <drm/drm_drv.h>
>> +#include <drm/drm_fb_helper.h>
>> +#include <drm/drm_file.h>
> Needed?
> 
>> +#include <drm/drm_format_helper.h>
>> +#include <drm/drm_fourcc.h>
>> +#include <drm/drm_gem_shmem_helper.h>
>> +#include <drm/drm_gem_framebuffer_helper.h>
>> +#include <drm/drm_ioctl.h>
>> +#include <drm/drm_managed.h>
>> +#include <drm/drm_modeset_helper_vtables.h>
>> +#include <drm/drm_probe_helper.h>
>> +#include <drm/drm_simple_kms_helper.h>
> 
>> +
>> +#define DRIVER_NAME "hyperv_drm"
>> +#define DRIVER_DESC "DRM driver for hyperv synthetic video device"
>> +#define DRIVER_DATE "2020"
>> +#define DRIVER_MAJOR 1
>> +#define DRIVER_MINOR 0
>> +
>> +#define VMBUS_MAX_PACKET_SIZE 0x4000
>> +#define VMBUS_RING_BUFSIZE (256 * 1024)
>> +#define VMBUS_VSP_TIMEOUT (10 * HZ)
>> +
>> +#define PCI_VENDOR_ID_MICROSOFT 0x1414
>> +#define PCI_DEVICE_ID_HYPERV_VIDEO 0x5353
>> +
>> +struct hyperv_device {
> 
> This is much more than a device - maybe just name it "struct hv"?

I think hyperv_device is good. And it's much more than just 'hv'.

> 
>> +	/* drm */
>> +	struct drm_device dev;
>> +	struct drm_simple_display_pipe pipe;
>> +	struct drm_connector connector;
>> +
>> +	/* mode */
>> +	u32 screen_width_max;
>> +	u32 screen_height_max;
>> +	u32 preferred_width;
>> +	u32 preferred_height;
>> +	u32 screen_depth;
>> +
>> +	/* hw */
>> +	void __iomem *vram;
>> +	unsigned long fb_base;
>> +	unsigned long fb_size;
>> +	struct completion wait;
>> +	u32 synthvid_version;
>> +	u32 mmio_megabytes;
>> +	bool init_done;

This field is unused. Please remove.

>> +
>> +	u8 init_buf[VMBUS_MAX_PACKET_SIZE];
>> +	u8 recv_buf[VMBUS_MAX_PACKET_SIZE];
>> +
>> +	struct hv_device *hdev;
>> +};
>> +
>> +#define to_hv(_dev) container_of(_dev, struct hyperv_device, dev)

Could this be a function?

>> +
>> +/* ---------------------------------------------------------------------- */
>> +/* Hyper-V Synthetic Video Protocol                                       */

The comments look awkward. Unless this style has been used within DRM,
maybe just use

 /*
  * ...
  */

>> +
>> +#define SYNTHVID_VERSION(major, minor) ((minor) << 16 | (major))
>> +#define SYNTHVID_VER_GET_MAJOR(ver) (ver & 0x0000ffff)
>> +#define SYNTHVID_VER_GET_MINOR(ver) ((ver & 0xffff0000) >> 16)
>> +#define SYNTHVID_VERSION_WIN7 SYNTHVID_VERSION(3, 0)
>> +#define SYNTHVID_VERSION_WIN8 SYNTHVID_VERSION(3, 2)
>> +#define SYNTHVID_VERSION_WIN10 SYNTHVID_VERSION(3, 5)
>> +
>> +#define SYNTHVID_DEPTH_WIN7 16
>> +#define SYNTHVID_DEPTH_WIN8 32
>> +#define SYNTHVID_FB_SIZE_WIN7 (4 * 1024 * 1024)
>> +#define SYNTHVID_FB_SIZE_WIN8 (8 * 1024 * 1024)
>> +#define SYNTHVID_WIDTH_MAX_WIN7 1600
>> +#define SYNTHVID_HEIGHT_MAX_WIN7 1200
>> +
>> +enum pipe_msg_type {
>> +	PIPE_MSG_INVALID,
>> +	PIPE_MSG_DATA,
>> +	PIPE_MSG_MAX
>> +};
>> +
>> +enum synthvid_msg_type {
>> +	SYNTHVID_ERROR			= 0,
>> +	SYNTHVID_VERSION_REQUEST	= 1,
>> +	SYNTHVID_VERSION_RESPONSE	= 2,
>> +	SYNTHVID_VRAM_LOCATION		= 3,
>> +	SYNTHVID_VRAM_LOCATION_ACK	= 4,
>> +	SYNTHVID_SITUATION_UPDATE	= 5,
>> +	SYNTHVID_SITUATION_UPDATE_ACK	= 6,
>> +	SYNTHVID_POINTER_POSITION	= 7,
>> +	SYNTHVID_POINTER_SHAPE		= 8,
>> +	SYNTHVID_FEATURE_CHANGE		= 9,
>> +	SYNTHVID_DIRT			= 10,
>> +	SYNTHVID_RESOLUTION_REQUEST	= 13,
>> +	SYNTHVID_RESOLUTION_RESPONSE	= 14,
>> +
>> +	SYNTHVID_MAX			= 15
>> +};
>> +
>> +struct pipe_msg_hdr {
>> +	u32 type;
>> +	u32 size; /* size of message after this field */
>> +} __packed;
>> +
>> +struct hvd_screen_info {
>> +	u16 width;
>> +	u16 height;
>> +} __packed;
>> +
>> +struct synthvid_msg_hdr {
>> +	u32 type;
>> +	u32 size;  /* size of this header + payload after this field*/
> Add space before closing "*/"
> 
> I wonder what is the difference between what is considered a message and
> what is considered payload in the above comments.
> Maybe that just because I do not know this stuff at all and the comment
> can be ignored.
> 
>> +} __packed;
>> +
>> +struct synthvid_version_req {
>> +	u32 version;
>> +} __packed;
>> +
>> +struct synthvid_version_resp {
>> +	u32 version;
>> +	u8 is_accepted;
>> +	u8 max_video_outputs;
>> +} __packed;
>> +
>> +struct synthvid_vram_location {
>> +	u64 user_ctx;
>> +	u8 is_vram_gpa_specified;
>> +	u64 vram_gpa;
>> +} __packed;
> Not an alignmnet friendly layout - but I guess the layout is fixed.
> Same goes in otther places.
> 
>> +
>> +struct synthvid_vram_location_ack {
>> +	u64 user_ctx;
>> +} __packed;
>> +
>> +struct video_output_situation {
>> +	u8 active;
>> +	u32 vram_offset;
>> +	u8 depth_bits;
>> +	u32 width_pixels;
>> +	u32 height_pixels;
>> +	u32 pitch_bytes;
>> +} __packed;
>> +
>> +struct synthvid_situation_update {
>> +	u64 user_ctx;
>> +	u8 video_output_count;
>> +	struct video_output_situation video_output[1];
>> +} __packed;
>> +
>> +struct synthvid_situation_update_ack {
>> +	u64 user_ctx;
>> +} __packed;
>> +
>> +struct synthvid_pointer_position {
>> +	u8 is_visible;
>> +	u8 video_output;
>> +	s32 image_x;
>> +	s32 image_y;
>> +} __packed;
>> +
>> +#define SYNTHVID_CURSOR_MAX_X 96
>> +#define SYNTHVID_CURSOR_MAX_Y 96
>> +#define SYNTHVID_CURSOR_ARGB_PIXEL_SIZE 4
>> +#define SYNTHVID_CURSOR_MAX_SIZE (SYNTHVID_CURSOR_MAX_X * \
>> +	SYNTHVID_CURSOR_MAX_Y * SYNTHVID_CURSOR_ARGB_PIXEL_SIZE)
>> +#define SYNTHVID_CURSOR_COMPLETE (-1)
>> +
>> +struct synthvid_pointer_shape {
>> +	u8 part_idx;
>> +	u8 is_argb;
>> +	u32 width; /* SYNTHVID_CURSOR_MAX_X at most */
>> +	u32 height; /* SYNTHVID_CURSOR_MAX_Y at most */
>> +	u32 hot_x; /* hotspot relative to upper-left of pointer image */
>> +	u32 hot_y;
>> +	u8 data[4];
>> +} __packed;
>> +
>> +struct synthvid_feature_change {
>> +	u8 is_dirt_needed;
>> +	u8 is_ptr_pos_needed;
>> +	u8 is_ptr_shape_needed;
>> +	u8 is_situ_needed;
>> +} __packed;
>> +
>> +struct rect {
>> +	s32 x1, y1; /* top left corner */
>> +	s32 x2, y2; /* bottom right corner, exclusive */
>> +} __packed;
>> +
>> +struct synthvid_dirt {
>> +	u8 video_output;
>> +	u8 dirt_count;
>> +	struct rect rect[1];
>> +} __packed;
>> +
>> +#define SYNTHVID_EDID_BLOCK_SIZE	128
>> +#define	SYNTHVID_MAX_RESOLUTION_COUNT	64
>> +
>> +struct synthvid_supported_resolution_req {
>> +	u8 maximum_resolution_count;
>> +} __packed;
>> +
>> +struct synthvid_supported_resolution_resp {
>> +	u8 edid_block[SYNTHVID_EDID_BLOCK_SIZE];
>> +	u8 resolution_count;
>> +	u8 default_resolution_index;
>> +	u8 is_standard;
>> +	struct hvd_screen_info supported_resolution[SYNTHVID_MAX_RESOLUTION_COUNT];
>> +} __packed;
>> +
>> +struct synthvid_msg {
>> +	struct pipe_msg_hdr pipe_hdr;
>> +	struct synthvid_msg_hdr vid_hdr;
>> +	union {
>> +		struct synthvid_version_req ver_req;
>> +		struct synthvid_version_resp ver_resp;
>> +		struct synthvid_vram_location vram;
>> +		struct synthvid_vram_location_ack vram_ack;
>> +		struct synthvid_situation_update situ;
>> +		struct synthvid_situation_update_ack situ_ack;
>> +		struct synthvid_pointer_position ptr_pos;
>> +		struct synthvid_pointer_shape ptr_shape;
>> +		struct synthvid_feature_change feature_chg;
>> +		struct synthvid_dirt dirt;
>> +		struct synthvid_supported_resolution_req resolution_req;
>> +		struct synthvid_supported_resolution_resp resolution_resp;
>> +	};
>> +} __packed;
>> +
>> +static inline bool synthvid_ver_ge(u32 ver1, u32 ver2)
>> +{
>> +	if (SYNTHVID_VER_GET_MAJOR(ver1) > SYNTHVID_VER_GET_MAJOR(ver2) ||
>> +	    (SYNTHVID_VER_GET_MAJOR(ver1) == SYNTHVID_VER_GET_MAJOR(ver2) &&
>> +	     SYNTHVID_VER_GET_MINOR(ver1) >= SYNTHVID_VER_GET_MINOR(ver2)))
>> +		return true;
>> +
>> +	return false;
>> +}
>> +
>> +static inline int synthvid_send(struct hv_device *hdev,
>> +				struct synthvid_msg *msg)
>> +{
>> +	static atomic64_t request_id = ATOMIC64_INIT(0);
>> +	int ret;
>> +
>> +	msg->pipe_hdr.type = PIPE_MSG_DATA;
>> +	msg->pipe_hdr.size = msg->vid_hdr.size;
>> +
>> +	ret = vmbus_sendpacket(hdev->channel, msg,
>> +			       msg->vid_hdr.size + sizeof(struct pipe_msg_hdr),
>> +			       atomic64_inc_return(&request_id),
>> +			       VM_PKT_DATA_INBAND, 0);
>> +
>> +	if (ret)
>> +		DRM_ERROR("Unable to send packet via vmbus\n");
> 
> Try to use drm_err() and friends, and not DRM_ERR and friends.
> DRM_ERR are no logner preferred in drivers.
> Goes for all uses of DRM_ERR and friends.
> 
>> +
>> +	return ret;
>> +}
>> +
>> +static int synthvid_negotiate_ver(struct hv_device *hdev, u32 ver)
>> +{
>> +	struct hyperv_device *hv = hv_get_drvdata(hdev);
>> +	struct synthvid_msg *msg = (struct synthvid_msg *)hv->init_buf;
>> +	unsigned long t;
>> +	int ret = 0;
>> +
>> +	memset(msg, 0, sizeof(struct synthvid_msg));
>> +	msg->vid_hdr.type = SYNTHVID_VERSION_REQUEST;
>> +	msg->vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
>> +		sizeof(struct synthvid_version_req);
>> +	msg->ver_req.version = ver;
>> +	synthvid_send(hdev, msg);
>> +
>> +	t = wait_for_completion_timeout(&hv->wait, VMBUS_VSP_TIMEOUT);
>> +	if (!t) {
>> +		DRM_ERROR("Time out on waiting version response\n");
>> +		ret = -ETIMEDOUT;
>> +		goto out;
>> +	}
>> +	if (!msg->ver_resp.is_accepted) {
>> +		ret = -ENODEV;
>> +		goto out;
>> +	}
>> +
>> +	hv->synthvid_version = ver;
>> +	DRM_INFO("Synthvid Version major %d, minor %d\n",
>> +		 SYNTHVID_VER_GET_MAJOR(ver), SYNTHVID_VER_GET_MINOR(ver));
>> +
>> +out:
>> +	return ret;
>> +}
>> +
>> +/* Should be done only once during init and resume */
>> +static int synthvid_update_vram_location(struct hv_device *hdev,
>> +					  phys_addr_t vram_pp)
>> +{
>> +	struct hyperv_device *hv = hv_get_drvdata(hdev);
>> +	struct synthvid_msg *msg = (struct synthvid_msg *)hv->init_buf;
>> +	unsigned long t;
>> +	int ret = 0;
>> +
>> +	memset(msg, 0, sizeof(struct synthvid_msg));
>> +	msg->vid_hdr.type = SYNTHVID_VRAM_LOCATION;
>> +	msg->vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
>> +		sizeof(struct synthvid_vram_location);
>> +	msg->vram.user_ctx = msg->vram.vram_gpa = vram_pp;
>> +	msg->vram.is_vram_gpa_specified = 1;
>> +	synthvid_send(hdev, msg);
>> +
>> +	t = wait_for_completion_timeout(&hv->wait, VMBUS_VSP_TIMEOUT);
>> +	if (!t) {
>> +		DRM_ERROR("Time out on waiting vram location ack\n");
>> +		ret = -ETIMEDOUT;
>> +		goto out;
>> +	}
>> +	if (msg->vram_ack.user_ctx != vram_pp) {
>> +		DRM_ERROR("Unable to set VRAM location\n");
>> +		ret = -ENODEV;
>> +	}
>> +
>> +out:
>> +	return ret;
>> +}
>> +
>> +static int synthvid_update_situation(struct hv_device *hdev, u8 active, u32 bpp,
>> +				     u32 w, u32 h, u32 pitch)
>> +{
>> +	struct synthvid_msg msg;
> 
> Sometimes synthvid_msg is hv->init_buf.
> Sometimes a local variable.
> I wonder why there is a difference.
> 
>> +
>> +	memset(&msg, 0, sizeof(struct synthvid_msg));
>> +
>> +	msg.vid_hdr.type = SYNTHVID_SITUATION_UPDATE;
>> +	msg.vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
>> +		sizeof(struct synthvid_situation_update);
>> +	msg.situ.user_ctx = 0;
>> +	msg.situ.video_output_count = 1;
>> +	msg.situ.video_output[0].active = active;
>> +	/* vram_offset should always be 0 */
>> +	msg.situ.video_output[0].vram_offset = 0;
>> +	msg.situ.video_output[0].depth_bits = bpp;
>> +	msg.situ.video_output[0].width_pixels = w;
>> +	msg.situ.video_output[0].height_pixels = h;
>> +	msg.situ.video_output[0].pitch_bytes = pitch;
>> +
>> +	synthvid_send(hdev, &msg);
>> +
>> +	return 0;
>> +}
>> +
>> +static int synthvid_update_dirt(struct hv_device *hdev, struct drm_rect *rect)
>> +{
>> +	struct synthvid_msg msg;
>> +
>> +	memset(&msg, 0, sizeof(struct synthvid_msg));
>> +
>> +	msg.vid_hdr.type = SYNTHVID_DIRT;
>> +	msg.vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
>> +		sizeof(struct synthvid_dirt);
>> +	msg.dirt.video_output = 0;
>> +	msg.dirt.dirt_count = 1;
>> +	msg.dirt.rect[0].x1 = rect->x1;
>> +	msg.dirt.rect[0].y1 = rect->y1;
>> +	msg.dirt.rect[0].x2 = rect->x2;
>> +	msg.dirt.rect[0].y2 = rect->y2;
>> +
>> +	synthvid_send(hdev, &msg);
>> +
>> +	return 0;
>> +}
>> +
>> +static int synthvid_get_supported_resolution(struct hv_device *hdev)
>> +{
>> +	struct hyperv_device *hv = hv_get_drvdata(hdev);
>> +	struct synthvid_msg *msg = (struct synthvid_msg *)hv->init_buf;
>> +	unsigned long t;
>> +	int ret = 0;
>> +	u8 index;
>> +	int i;
>> +
>> +	memset(msg, 0, sizeof(struct synthvid_msg));
>> +	msg->vid_hdr.type = SYNTHVID_RESOLUTION_REQUEST;
>> +	msg->vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
>> +		sizeof(struct synthvid_supported_resolution_req);
>> +	msg->resolution_req.maximum_resolution_count =
>> +		SYNTHVID_MAX_RESOLUTION_COUNT;
>> +	synthvid_send(hdev, msg);
>> +
>> +	t = wait_for_completion_timeout(&hv->wait, VMBUS_VSP_TIMEOUT);
>> +	if (!t) {
>> +		DRM_ERROR("Time out on waiting resolution response\n");
>> +		ret = -ETIMEDOUT;
>> +		goto out;
>> +	}
>> +
>> +	if (msg->resolution_resp.resolution_count == 0) {
>> +		DRM_ERROR("No supported resolutions\n");
>> +		ret = -ENODEV;
>> +		goto out;
>> +	}
>> +
>> +	index = msg->resolution_resp.default_resolution_index;
>> +	if (index >= msg->resolution_resp.resolution_count) {
>> +		DRM_ERROR("Invalid resolution index: %d\n", index);
>> +		ret = -ENODEV;
>> +		goto out;
>> +	}
>> +
>> +	for (i = 0; i < msg->resolution_resp.resolution_count; i++) {
>> +		hv->screen_width_max = max_t(u32, hv->screen_width_max,
>> +			msg->resolution_resp.supported_resolution[i].width);
>> +		hv->screen_height_max = max_t(u32, hv->screen_height_max,
>> +			msg->resolution_resp.supported_resolution[i].height);
>> +	}
>> +
>> +	hv->preferred_width =
>> +		msg->resolution_resp.supported_resolution[index].width;
>> +	hv->preferred_height =
>> +		msg->resolution_resp.supported_resolution[index].height;
>> +
>> +out:
>> +	return ret;
>> +}
>> +
>> +/* Actions on received messages from host */
>> +static void synthvid_recv_sub(struct hv_device *hdev)
>> +{
>> +	struct hyperv_device *hv = hv_get_drvdata(hdev);
>> +	struct synthvid_msg *msg;
>> +
>> +	if (!hv)
>> +		return;
>> +
>> +	msg = (struct synthvid_msg *)hv->recv_buf;
>> +
>> +	/* Complete the wait event */
>> +	if (msg->vid_hdr.type == SYNTHVID_VERSION_RESPONSE ||
>> +	    msg->vid_hdr.type == SYNTHVID_RESOLUTION_RESPONSE ||
>> +	    msg->vid_hdr.type == SYNTHVID_VRAM_LOCATION_ACK) {
>> +		memcpy(hv->init_buf, msg, VMBUS_MAX_PACKET_SIZE);
>> +		complete(&hv->wait);
>> +		return;
>> +	}
>> +}
>> +
>> +static void synthvid_receive(void *ctx)
>> +{
>> +	struct hv_device *hdev = ctx;
>> +	struct hyperv_device *hv = hv_get_drvdata(hdev);
>> +	struct synthvid_msg *recv_buf;
>> +	u32 bytes_recvd;
>> +	u64 req_id;
>> +	int ret;
>> +
>> +	if (!hv)
>> +		return;
>> +
>> +	recv_buf = (struct synthvid_msg *)hv->recv_buf;
>> +
>> +	do {
>> +		ret = vmbus_recvpacket(hdev->channel, recv_buf,
>> +				       VMBUS_MAX_PACKET_SIZE,
>> +				       &bytes_recvd, &req_id);
>> +		if (bytes_recvd > 0 &&
>> +		    recv_buf->pipe_hdr.type == PIPE_MSG_DATA)
>> +			synthvid_recv_sub(hdev);
>> +	} while (bytes_recvd > 0 && ret == 0);
>> +}
>> +
>> +static int synthvid_connect_vsp(struct hv_device *hdev)
>> +{
>> +	struct hyperv_device *hv = hv_get_drvdata(hdev);
>> +	int ret;
>> +
>> +	ret = vmbus_open(hdev->channel, VMBUS_RING_BUFSIZE, VMBUS_RING_BUFSIZE,
>> +			 NULL, 0, synthvid_receive, hdev);
>> +	if (ret) {
>> +		DRM_ERROR("Unable to open vmbus channel\n");
>> +		return ret;
>> +	}
>> +
>> +	/* Negotiate the protocol version with host */
>> +	switch (vmbus_proto_version) {
>> +	case VERSION_WIN10:
>> +	case VERSION_WIN10_V5:
>> +		ret = synthvid_negotiate_ver(hdev, SYNTHVID_VERSION_WIN10);
>> +		if (!ret)
>> +			break;
>> +		fallthrough;
>> +	case VERSION_WIN8:
>> +	case VERSION_WIN8_1:
>> +		ret = synthvid_negotiate_ver(hdev, SYNTHVID_VERSION_WIN8);
>> +		if (!ret)
>> +			break;
>> +		fallthrough;
>> +	case VERSION_WS2008:
>> +	case VERSION_WIN7:
>> +		ret = synthvid_negotiate_ver(hdev, SYNTHVID_VERSION_WIN7);
>> +		break;
>> +	default:
>> +		ret = synthvid_negotiate_ver(hdev, SYNTHVID_VERSION_WIN10);
>> +		break;
>> +	}
>> +
>> +	if (ret) {
>> +		DRM_ERROR("Synthetic video device version not accepted\n");
> Print error code?
> 
>> +		goto error;
>> +	}
>> +
>> +	if (hv->synthvid_version == SYNTHVID_VERSION_WIN7)
>> +		hv->screen_depth = SYNTHVID_DEPTH_WIN7;
>> +	else
>> +		hv->screen_depth = SYNTHVID_DEPTH_WIN8;
>> +
>> +	if (synthvid_ver_ge(hv->synthvid_version, SYNTHVID_VERSION_WIN10)) {
>> +		ret = synthvid_get_supported_resolution(hdev);
>> +		if (ret)
>> +			DRM_ERROR("Failed to get supported resolution from host, use default\n");
>> +	} else {
>> +		hv->screen_width_max = SYNTHVID_WIDTH_MAX_WIN7;
>> +		hv->screen_height_max = SYNTHVID_HEIGHT_MAX_WIN7;
>> +	}
>> +
>> +	hv->mmio_megabytes = hdev->channel->offermsg.offer.mmio_megabytes;
>> +
>> +	return 0;
>> +
>> +error:
>> +	vmbus_close(hdev->channel);
>> +	return ret;
>> +}
>> +
>> +/* ---------------------------------------------------------------------- */
>> +/* VRAM blit                                                              */
>> +
>> +static int hyperv_blit_to_vram_rect(struct drm_framebuffer *fb,
>> +				    struct drm_rect *rect)
>> +{
>> +	struct hyperv_device *hv = to_hv(fb->dev);
>> +	void *vmap;
>> +	int idx, ret;
>> +
>> +	ret = -ENODEV;
>> +	if (!drm_dev_enter(&hv->dev, &idx))
>> +		goto out;

Return -ENODEV directly.

>> +
>> +	ret = -ENOMEM;
>> +	vmap = drm_gem_shmem_vmap(fb->obj[0]);
>> +	if (!vmap)
>> +		goto out_dev_exit;
>> +
>> +	drm_fb_memcpy_dstclip(hv->vram, vmap, fb, rect);
>> +	drm_gem_shmem_vunmap(fb->obj[0], vmap);
>> +	ret = 0;
>> +
>> +out_dev_exit:
>> +	drm_dev_exit(idx);
>> +out:
>> +	return ret;

IMHO rather separate regular cleanups from error rollbacks. Handling
both in the same code is hard to read and usually not worth the amount
of saved LOCs.

>> +}
>> +
>> +static int hyperv_blit_to_vram_fullscreen(struct drm_framebuffer *fb)
>> +{
>> +	struct drm_rect fullscreen = {
>> +		.x1 = 0,
>> +		.x2 = fb->width,
>> +		.y1 = 0,
>> +		.y2 = fb->height,
>> +	};
>> +	return hyperv_blit_to_vram_rect(fb, &fullscreen);
>> +}
>> +
>> +/* ---------------------------------------------------------------------- */
>> +/* connector                                                              */
>> +
>> +static int hyperv_connector_get_modes(struct drm_connector *connector)
>> +{
>> +	struct hyperv_device *hv = to_hv(connector->dev);
>> +	int count;
>> +
>> +	count = drm_add_modes_noedid(connector,
>> +				     connector->dev->mode_config.max_width,
>> +				     connector->dev->mode_config.max_height);
>> +	drm_set_preferred_mode(connector, hv->preferred_width,
>> +			       hv->preferred_height);
>> +
>> +	return count;
>> +}
>> +
>> +static const struct drm_connector_helper_funcs hyperv_connector_helper_funcs = {
>> +	.get_modes = hyperv_connector_get_modes,
>> +};
>> +
>> +static const struct drm_connector_funcs hyperv_connector_funcs = {
>> +	.fill_modes = drm_helper_probe_single_connector_modes,
>> +	.destroy = drm_connector_cleanup,
>> +	.reset = drm_atomic_helper_connector_reset,
>> +	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
>> +	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
>> +};
>> +
>> +static int hyperv_conn_init(struct hyperv_device *hv)
>> +{
>> +	drm_connector_helper_add(&hv->connector, &hyperv_connector_helper_funcs);
>> +	return drm_connector_init(&hv->dev, &hv->connector,
>> +				  &hyperv_connector_funcs,
>> +				  DRM_MODE_CONNECTOR_VGA);
>> +
>> +}
>> +
>> +/* ---------------------------------------------------------------------- */
>> +/* display pipe                                                           */
>> +
>> +static int hyperv_check_size(struct hyperv_device *hv, int w, int h,
>> +			     struct drm_framebuffer *fb)
>> +{
>> +	u32 pitch = w * (hv->screen_depth/8);
>> +
>> +	if (fb)
>> +		pitch = fb->pitches[0];
>> +
>> +	if (pitch * h > hv->fb_size)
>> +		return -EINVAL;
>> +
>> +	return 0;
>> +}
>> +
>> +static enum drm_mode_status
>> +hyperv_pipe_mode_valid(struct drm_simple_display_pipe *pipe,
>> +		       const struct drm_display_mode *mode)
>> +{
>> +	struct hyperv_device *hv = to_hv(pipe->crtc.dev);
>> +
>> +	if (hyperv_check_size(hv, mode->hdisplay, mode->vdisplay, NULL))
>> +		return MODE_BAD;
>> +
>> +	return MODE_OK;
>> +}
>> +
>> +static void hyperv_pipe_enable(struct drm_simple_display_pipe *pipe,
>> +			       struct drm_crtc_state *crtc_state,
>> +			       struct drm_plane_state *plane_state)
>> +{
>> +	struct hyperv_device *hv = to_hv(pipe->crtc.dev);
>> +
>> +	synthvid_update_situation(hv->hdev, 1,  hv->screen_depth,
>> +				  crtc_state->mode.hdisplay,
>> +				  crtc_state->mode.vdisplay,
>> +				  plane_state->fb->pitches[0]);
>> +	hyperv_blit_to_vram_fullscreen(plane_state->fb);
>> +}
>> +
>> +static void hyperv_pipe_update(struct drm_simple_display_pipe *pipe,
>> +			      struct drm_plane_state *old_state)
>> +{
>> +	struct hyperv_device *hv = to_hv(pipe->crtc.dev);
>> +	struct drm_plane_state *state = pipe->plane.state;
>> +	struct drm_rect rect;
>> +
>> +	if (drm_atomic_helper_damage_merged(old_state, state, &rect)) {
>> +		hyperv_blit_to_vram_rect(state->fb, &rect);
>> +		synthvid_update_dirt(hv->hdev, &rect);
>> +	}
>> +}
>> +
>> +static const struct drm_simple_display_pipe_funcs hyperv_pipe_funcs = {
>> +	.mode_valid = hyperv_pipe_mode_valid,
>> +	.enable	= hyperv_pipe_enable,
>> +	.update	= hyperv_pipe_update,
>> +};
>> +
>> +static const uint32_t hyperv_formats[] = {
>> +	DRM_FORMAT_XRGB8888,
>> +};
>> +
>> +static const uint64_t hyperv_modifiers[] = {
>> +	DRM_FORMAT_MOD_LINEAR,
>> +	DRM_FORMAT_MOD_INVALID
>> +};
>> +
>> +static int hyperv_pipe_init(struct hyperv_device *hv)
>> +{
>> +	int ret;
>> +
>> +	ret = drm_simple_display_pipe_init(&hv->dev,
>> +					   &hv->pipe,
>> +					   &hyperv_pipe_funcs,
>> +					   hyperv_formats,
>> +					   ARRAY_SIZE(hyperv_formats),
>> +					   NULL,
>> +					   &hv->connector);
>> +
>> +	drm_plane_enable_fb_damage_clips(&(hv->pipe.plane));
>> +
>> +	return ret;
>> +}
>> +
>> +/* ---------------------------------------------------------------------- */
>> +/* framebuffers & mode config                                             */
>> +
>> +static struct drm_framebuffer*
>> +hyperv_fb_create(struct drm_device *dev, struct drm_file *file_priv,
>> +		 const struct drm_mode_fb_cmd2 *mode_cmd)
>> +{
>> +	struct hyperv_device *hv = to_hv(dev);
>> +
>> +	if (mode_cmd->pixel_format != DRM_FORMAT_XRGB8888)
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	if (mode_cmd->pitches[0] * mode_cmd->height > hv->fb_size)
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	return drm_gem_fb_create_with_dirty(dev, file_priv, mode_cmd);
>> +}
>> +
>> +static const struct drm_mode_config_funcs hyperv_mode_config_funcs = {
>> +	.fb_create = hyperv_fb_create,
>> +	.atomic_check = drm_atomic_helper_check,
>> +	.atomic_commit = drm_atomic_helper_commit,
>> +};
>> +
>> +static int hyperv_mode_config_init(struct hyperv_device *hv)
>> +{
>> +	struct drm_device *dev = &hv->dev;
>> +	int ret;
>> +
>> +	ret = drmm_mode_config_init(dev);
>> +	if (ret)
>> +		return ret;
>> +
>> +	dev->mode_config.min_width = 0;
>> +	dev->mode_config.min_height = 0;
>> +	dev->mode_config.max_width = hv->screen_width_max;
>> +	dev->mode_config.max_height = hv->screen_height_max;
>> +
>> +	dev->mode_config.preferred_depth = hv->screen_depth;
>> +	dev->mode_config.prefer_shadow = 0;
>> +
>> +	dev->mode_config.funcs = &hyperv_mode_config_funcs;
>> +
>> +	return 0;
>> +}
>> +
>> +/* ---------------------------------------------------------------------- */
>> +/* DRM                                                                    */
>> +
>> +DEFINE_DRM_GEM_FOPS(hv_fops);
>> +
>> +static struct drm_driver hyperv_driver = {
>> +	.driver_features = DRIVER_MODESET | DRIVER_GEM | DRIVER_ATOMIC,
>> +
>> +	.name		 = DRIVER_NAME,
>> +	.desc		 = DRIVER_DESC,
>> +	.date		 = DRIVER_DATE,
>> +	.major		 = DRIVER_MAJOR,
>> +	.minor		 = DRIVER_MINOR,
>> +
>> +	.fops		 = &hv_fops,
>> +	DRM_GEM_SHMEM_DRIVER_OPS,
>> +};
>> +
>> +/* ---------------------------------------------------------------------- */
>> +/* pci/vmbus interface                                                    */
>> +
>> +static int hyperv_pci_probe(struct pci_dev *pdev,
>> +			    const struct pci_device_id *ent)
>> +{
>> +	return 0;
>> +}
>> +
>> +static void hyperv_pci_remove(struct pci_dev *pdev)
>> +{
>> +}
>> +
>> +static const struct pci_device_id hyperv_pci_tbl[] = {
>> +	{
>> +		.vendor = PCI_VENDOR_ID_MICROSOFT,
>> +		.device = PCI_DEVICE_ID_HYPERV_VIDEO,
>> +	},
>> +	{ /* end of list */ }
>> +};
>> +
>> +static struct pci_driver hyperv_pci_driver = {
>> +	.name =		KBUILD_MODNAME,
>> +	.id_table =	hyperv_pci_tbl,
>> +	.probe =	hyperv_pci_probe,
>> +	.remove =	hyperv_pci_remove,
>> +};
>> +
>> +static int hyperv_vmbus_probe(struct hv_device *hdev,
>> +			      const struct hv_vmbus_device_id *dev_id)
>> +{
>> +	struct hyperv_device *hv;
>> +	struct drm_device *dev;
>> +	struct pci_dev *pdev;
>> +	int ret;
>> +
>> +	hv = devm_drm_dev_alloc(&hdev->device, &hyperv_driver,
>> +				struct hyperv_device, dev);
>> +	if (IS_ERR(hv))
>> +		return PTR_ERR(hv);
>> +
>> +	dev = &hv->dev;
>> +	init_completion(&hv->wait);
>> +	hv_set_drvdata(hdev, hv);
>> +	hv->hdev = hdev;
>> +
>> +	pdev = pci_get_device(PCI_VENDOR_ID_MICROSOFT,
>> +			      PCI_DEVICE_ID_HYPERV_VIDEO, NULL);
>> +	if (!pdev) {
>> +		DRM_ERROR("Unable to find PCI Hyper-V video\n");
>> +		return -ENODEV;
>> +	}
>> +
>> +	ret = drm_fb_helper_remove_conflicting_pci_framebuffers(pdev, "hypervdrmfb");
>> +	if (ret) {
>> +		DRM_ERROR("Not able to remove boot fb\n");
>> +		goto error;
>> +	}
>> +
>> +	if (pci_request_region(pdev, 0, DRIVER_NAME) != 0)
>> +		DRM_WARN("Cannot request framebuffer, boot fb still active?\n");
> devm variant?
> 
>> +
>> +	if ((pdev->resource[0].flags & IORESOURCE_MEM) == 0) {
>> +		DRM_ERROR("Resource at bar 0 is not IORESOURCE_MEM\n");
>> +		ret = -ENODEV;
>> +		goto error;
>> +	}
>> +
>> +	hv->fb_base = pci_resource_start(pdev, 0);
>> +	hv->fb_size = pci_resource_len(pdev, 0);
>> +	if (hv->fb_base == 0) {
>> +		DRM_ERROR("Resource not available\n");
>> +		ret = -ENODEV;
>> +		goto error;
>> +	}
>> +
>> +	/* Get the actual VRAM size from the device */
>> +	ret = synthvid_connect_vsp(hdev);
>> +	if (ret) {
>> +		DRM_ERROR("Failed to connect to vmbus\n");
>> +		goto error;
>> +	}
>> +
>> +	hv->fb_size = min(hv->fb_size,
>> +			  (unsigned long)(hv->mmio_megabytes * 1024 * 1024));
>> +	hv->vram = devm_ioremap(&pdev->dev, hv->fb_base, hv->fb_size);
>> +	if (hv->vram == NULL) {
>> +		DRM_ERROR("Failed to map vram\n");
>> +		ret = -ENOMEM;
>> +		goto error1;
>> +	}
>> +
>> +	/*
>> +	 * Failing to update vram location is not fatal. Device will update
>> +	 * dirty area till preferred resolution only.
>> +	 */
>> +	ret = synthvid_update_vram_location(hdev, hv->fb_base);
>> +	if (ret)
>> +		DRM_WARN("Failed to update vram location.\n");

I'd put the memory initialization, beginning at
"pci_request_region(pdev, 0, DRIVER_NAME)", into a separate function.


>> +
>> +	ret = hyperv_mode_config_init(hv);
>> +	if (ret) {
>> +		DRM_ERROR("Failed to initialized mode setting\n");
>> +		goto error1;
>> +	}
>> +
>> +	ret = hyperv_conn_init(hv);
>> +	if (ret) {
>> +		DRM_ERROR("Failed to initialized connector\n");
>> +		goto error1;
>> +	}
>> +
>> +	ret = hyperv_pipe_init(hv);
>> +	if (ret) {
>> +		DRM_ERROR("Failed to initialized pipe\n");
>> +		goto error1;
>> +	}
>> +
>> +	drm_mode_config_reset(dev);

The code up to here could go into hyperv_mode_config_init().

>> +
>> +	ret = drm_dev_register(dev, 0);
>> +	if (ret) {
>> +		DRM_ERROR("Failed to register drm driver\n");
>> +		goto error1;
>> +	}
>> +
>> +	drm_fbdev_generic_setup(dev, dev->mode_config.preferred_depth);

Simply pass 0 as final argument. The helper will use the preferred depth
automatically.

>> +
>> +	pci_dev_put(pdev);
>> +	return 0;
>> +
>> +error1:
>> +	vmbus_close(hdev->channel);
>> +error:

There lables are badly named. Rather use err_vmbus_close and
err_hv_set_drv_data.

Best regards
Thomas

>> +	hv_set_drvdata(hdev, NULL);
>> +	pci_dev_put(pdev);
>> +	return ret;
>> +}
>> +
>> +static int hyperv_vmbus_remove(struct hv_device *hdev)
>> +{
>> +	struct drm_device *dev = hv_get_drvdata(hdev);
>> +
>> +	drm_dev_unplug(dev);
>> +	drm_atomic_helper_shutdown(dev);
>> +	vmbus_close(hdev->channel);
>> +	hv_set_drvdata(hdev, NULL);
>> +
>> +	return 0;
>> +}
>> +
>> +static int hyperv_vmbus_suspend(struct hv_device *hdev)
>> +{
>> +	struct drm_device *dev = hv_get_drvdata(hdev);
>> +	int ret;
>> +
>> +	ret = drm_mode_config_helper_suspend(dev);
>> +
>> +	vmbus_close(hdev->channel);
>> +
>> +	return ret;
>> +}
>> +
>> +static int hyperv_vmbus_resume(struct hv_device *hdev)
>> +{
>> +	struct drm_device *dev = hv_get_drvdata(hdev);
>> +	int ret;
>> +
>> +	ret = synthvid_connect_vsp(hdev);
>> +	if (ret)
>> +		return ret;
>> +
>> +	return drm_mode_config_helper_resume(dev);
>> +}
>> +
>> +static const struct hv_vmbus_device_id hyperv_vmbus_tbl[] = {
>> +	/* Synthetic Video Device GUID */
>> +	{HV_SYNTHVID_GUID},
>> +	{}
>> +};
>> +
>> +static struct hv_driver hyperv_hv_driver = {
>> +	.name = KBUILD_MODNAME,
>> +	.id_table = hyperv_vmbus_tbl,
>> +	.probe = hyperv_vmbus_probe,
>> +	.remove = hyperv_vmbus_remove,
>> +	.suspend = hyperv_vmbus_suspend,
>> +	.resume = hyperv_vmbus_resume,
>> +	.driver = {
>> +		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
>> +	},
>> +};
>> +
>> +/* ---------------------------------------------------------------------- */
>> +/* module init/exit                                                       */
>> +
>> +static int __init hyperv_init(void)
>> +{
>> +	int ret;
>> +
>> +	ret = pci_register_driver(&hyperv_pci_driver);
>> +	if (ret != 0) {
>> +		DRM_ERROR("Failed to register pci driver\n");
>> +		return ret;
>> +	}
>> +
>> +	ret = vmbus_driver_register(&hyperv_hv_driver);
>> +	if (ret != 0)
>> +		DRM_ERROR("Failed to register vmbus driver\n");
>> +
>> +	return ret;
>> +}
>> +
>> +static void __exit hyperv_exit(void)
>> +{
>> +	vmbus_driver_unregister(&hyperv_hv_driver);
>> +	pci_unregister_driver(&hyperv_pci_driver);
>> +}
>> +
>> +module_init(hyperv_init);
>> +module_exit(hyperv_exit);
>> +
>> +MODULE_DEVICE_TABLE(pci, hyperv_pci_tbl);
>> +MODULE_DEVICE_TABLE(vmbus, hyperv_vmbus_tbl);
>> +MODULE_LICENSE("GPL");
>> +MODULE_AUTHOR("Deepak Rawat <drawat.floss@gmail.com>");
>> +MODULE_DESCRIPTION("DRM driver for hyperv synthetic video device");
>> -- 
>> 2.27.0
>>
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel@lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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Re: [RFC PATCH 1/2] drm/hyperv: Add DRM driver for hyperv synthetic video device

[Deepak Rawat]

On Tue, 2020-06-23 at 09:59 +0200, Thomas Zimmermann wrote:
> Hi Deepak
> 
> I did not receive you pat series, so I can only comment on Sam's
> reply.
> See below for some points.

Hi Thomas, Thanks for the review. I wanted to add you in cc list but
messed it up with final git send-email. Sorry about that. I am not sure
why you didn't received it via dri-devel. The patch series do show up
in dri-devel archive. I wonder if other people also have similar
issues.


> > > 
> > > +	struct hv_device *hdev;
> > > +};
> > > +
> > > +#define to_hv(_dev) container_of(_dev, struct hyperv_device,
> > > dev)
> 
> Could this be a function?

Is there a reason to use a function here?

> 
> > > +
> > > +/* -----------------------------------------------------------
> > > ----------- */
> > > +/* Hyper-V Synthetic Video
> > > Protocol                                       */
> 
> The comments look awkward. Unless this style has been used within
> DRM,
> maybe just use
> 
>  /*
>   * ...
>   */
> 

This style is copy-paste from cirrus, and bochs also have same style.
Perhaps historical. Anyway I agree to I should get rid of this.

Re: [RFC PATCH 1/2] drm/hyperv: Add DRM driver for hyperv synthetic video device

[Thomas Zimmermann]

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Hi

Am 23.06.20 um 11:12 schrieb Deepak Rawat:
> On Tue, 2020-06-23 at 09:59 +0200, Thomas Zimmermann wrote:
>> Hi Deepak
>>
>> I did not receive you pat series, so I can only comment on Sam's
>> reply.
>> See below for some points.
> 
> Hi Thomas, Thanks for the review. I wanted to add you in cc list but
> messed it up with final git send-email. Sorry about that. I am not sure
> why you didn't received it via dri-devel. The patch series do show up
> in dri-devel archive. I wonder if other people also have similar
> issues.

I think it's related to a problem on my side. Some of my email
infrastructure was not available over the weekend.

Best regards
Thomas

> 
> 
>>>>
>>>> +	struct hv_device *hdev;
>>>> +};
>>>> +
>>>> +#define to_hv(_dev) container_of(_dev, struct hyperv_device,
>>>> dev)
>>
>> Could this be a function?
> 
> Is there a reason to use a function here?
> 
>>
>>>> +
>>>> +/* -----------------------------------------------------------
>>>> ----------- */
>>>> +/* Hyper-V Synthetic Video
>>>> Protocol                                       */
>>
>> The comments look awkward. Unless this style has been used within
>> DRM,
>> maybe just use
>>
>>  /*
>>   * ...
>>   */
>>
> 
> This style is copy-paste from cirrus, and bochs also have same style.
> Perhaps historical. Anyway I agree to I should get rid of this.
> 
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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Re: [RFC PATCH 1/2] drm/hyperv: Add DRM driver for hyperv synthetic video device

[Daniel Vetter]

On Mon, Jun 22, 2020 at 03:20:34PM -0700, Deepak Rawat wrote:
> On Mon, 2020-06-22 at 14:46 +0200, Gerd Hoffmann wrote:
> >   Hi,
> > 
> > > +/* Should be done only once during init and resume */
> > > +static int synthvid_update_vram_location(struct hv_device *hdev,
> > > +					  phys_addr_t vram_pp)
> > > +{
> > > +	struct hyperv_device *hv = hv_get_drvdata(hdev);
> > > +	struct synthvid_msg *msg = (struct synthvid_msg *)hv->init_buf;
> > > +	unsigned long t;
> > > +	int ret = 0;
> > > +
> > > +	memset(msg, 0, sizeof(struct synthvid_msg));
> > > +	msg->vid_hdr.type = SYNTHVID_VRAM_LOCATION;
> > > +	msg->vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
> > > +		sizeof(struct synthvid_vram_location);
> > > +	msg->vram.user_ctx = msg->vram.vram_gpa = vram_pp;
> > > +	msg->vram.is_vram_gpa_specified = 1;
> > > +	synthvid_send(hdev, msg);
> > 
> > That suggests it is possible to define multiple framebuffers in vram,
> > then pageflip by setting vram.vram_gpa.  If that is the case I'm
> > wondering whenever vram helpers are a better fit maybe?  You don't
> > have
> > to blit each and every display update then.
> 
> Thanks for the review. Unfortunately only the first vmbus message take
> effect and subsequent calls are ignored. I originally implemented using
> vram helpers but I figured out calling this vmbus message again won't
> change the vram location.

I think that needs a very big comment. Maybe even enforce that with a
"vram_gpa_set" boolean in the device structure, and complain if we try to
do that twice.

Also I guess congrats to microsoft for defining things like that :-/
-Daniel

> 
> > 
> > FYI: cirrus goes the blit route because (a) the amount of vram is
> > very
> > small so trying to store multiple framebuffers there is out of
> > question,
> > and (b) cirrus converts formats on the fly to hide some hardware
> > oddities.
> > 
> > take care,
> >   Gerd
> > 
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

Re: [RFC PATCH 1/2] drm/hyperv: Add DRM driver for hyperv synthetic video device

[Gerd Hoffmann]

  Hi,

> > > > +	msg->vram.user_ctx = msg->vram.vram_gpa = vram_pp;
> > > > +	msg->vram.is_vram_gpa_specified = 1;
> > > > +	synthvid_send(hdev, msg);
> > > 
> > > That suggests it is possible to define multiple framebuffers in vram,
> > > then pageflip by setting vram.vram_gpa.  If that is the case I'm
> > > wondering whenever vram helpers are a better fit maybe?  You don't
> > > have
> > > to blit each and every display update then.
> > 
> > Thanks for the review. Unfortunately only the first vmbus message take
> > effect and subsequent calls are ignored. I originally implemented using
> > vram helpers but I figured out calling this vmbus message again won't
> > change the vram location.

/me notices there also is user_ctx.  What is this?

> I think that needs a very big comment. Maybe even enforce that with a
> "vram_gpa_set" boolean in the device structure, and complain if we try to
> do that twice.
> 
> Also I guess congrats to microsoft for defining things like that :-/

I would be kind of surprised if the virtual device doesn't support
pageflips.  Maybe setting vram_gpa just isn't the correct way to do
it.  Is there a specification available?

There are a number of microsoft folks in Cc:  Anyone willing to comment?

thanks,
  Gerd

PS: And, yes, in case pageflips really don't work going with shmem
    helpers + blits is reasonable.

RE: [RFC PATCH 1/2] drm/hyperv: Add DRM driver for hyperv synthetic video device

[Dexuan Cui]

> From: linux-hyperv-owner@vger.kernel.org
> <linux-hyperv-owner@vger.kernel.org> On Behalf Of Deepak Rawat
> Sent: Monday, June 22, 2020 11:49 PM
> > [...]
> > Some quick comments:
> > 1. hyperv_vmbus_probe() assumes the existence of the PCI device,
> > which
> > is not true in a Hyper-V Generation-2 VM.
> 
> I guess that mean for Gen-2 VM need to rely on vmbus_allocate_mmio to
> get the VRAM memory? From what I understand the pci interface anyway
> maps to vmbus.

In a Hyper-V Generaton-2 VM, there is not the legacy Hyper-V PCI framebuffer
device, so we have to call vmbus_allocate_mmio() to get a proper MMIO 
range and use that as the VRAM memory.

BTW, what's the equivlent of FB_DEFERRED_IO in DRM? Have the patch
implemented the similar thing for DRM like this for FB in this patch:
d21987d709e8 ("video: hyperv: hyperv_fb: Support deferred IO for Hyper-V frame buffer driver")

There is also another important performance improvement patch:
3a6fb6c4255c ("video: hyperv: hyperv_fb: Use physical memory for fb on HyperV Gen 1 VMs.")
Is the same idea applicable to this DRM patch?

The pci-hyperv FB driver and this DRM driver should not try to load at
the same time. Not sure what should be done to make sure that won't happen.

> > 2. It looks some other functionality in the hyperv_fb driver has not
> > been
> > implemented in this new driver either, e.g. the handling of the
> > SYNTHVID_FEATURE_CHANGE msg.
> 
> I deliberately left this and things seems to work without this, maybe I
> need to do more testing. I don't really understand the use-case
> of SYNTHVID_FEATURE_CHANGE. I observed this message was received just
> after vmbus connect and DRM is not yet initialized so no point updating
> the situation. Even otherwise situation (mode, damage, etc.) is
> triggered from user-space, not sure what to update. But will definitely
> clarify on this.

When Linux VM updates the VRAM, Linux should notify the host of the
dirty rectangle, and then the host refreshes the rectangle in the VM
Connectin window so the user sees the updated part of the screen.

I remember when the user closes the VM Connection window, the host
sends the VM a msg with msg->feature_chg.is_dirt_needed=0, so the VM
doesn't have to notify the host of the dirty rectangle; when the VM
Connection program runs again, the VM will receive a msg with
msg->feature_chg.is_dirt_needed=1.

Thanks,
-- Dexuan

Re: [RFC PATCH 1/2] drm/hyperv: Add DRM driver for hyperv synthetic video device

[Deepak Rawat]

> > > Thanks for the review. Unfortunately only the first vmbus message
> > > take
> > > effect and subsequent calls are ignored. I originally implemented
> > > using
> > > vram helpers but I figured out calling this vmbus message again
> > > won't
> > > change the vram location.
> 
> /me notices there also is user_ctx.  What is this?

Not sure, I will try to get in touch with hyper-v folks internally to
see if page-flip can be used.

> 
> > I think that needs a very big comment. Maybe even enforce that with
> > a
> > "vram_gpa_set" boolean in the device structure, and complain if we
> > try to
> > do that twice.
> > 
> > Also I guess congrats to microsoft for defining things like that :-
> > /
> 
> I would be kind of surprised if the virtual device doesn't support
> pageflips.  Maybe setting vram_gpa just isn't the correct way to do
> it.  Is there a specification available?
> 
> There are a number of microsoft folks in Cc:  Anyone willing to
> comment?
> 
> thanks,
>   Gerd
> 
> PS: And, yes, in case pageflips really don't work going with shmem
>     helpers + blits is reasonable.
> 

Re: [RFC PATCH 0/2] DRM driver for hyper-v synthetic video device

[Daniel Vetter]

On Mon, Jun 22, 2020 at 1:07 PM Deepak Rawat <drawat.floss@gmail.com> wrote:
>
> Hi All,
>
> First draft of DRM driver for hyper-v synthetic video device. This synthetic
> device is already supported by hyper-v and a corresponding framebuffer driver
> exist at drivers/video/fbdev/hyperv_fb.c. With this patch, just reworked the
> framebuffer driver into DRM, in doing so got mode-setting support. The code is
> similar to cirrus DRM driver, using simple display pipe and shmem backed
> GEM objects.
>
> The device support more features like hardware cursor, EDID, multiple dirty
> regions, etc, which were not supported with framebuffer driver. The plan is to
> add support for those in future iteration. Wanted to get initial feedback and
> discuss cursor support with simple kms helper. Is there any value to add cursor
> support to drm_simple_kms_helper.c so that others can use it, or should I just
> add cursor plane as device private? I believe we can still keep this driver
> in drm/tiny?

Simple is for really simple framebuffers, if you want a few planes or
multiple outputs or multiple crtcs then just write a normal drm
driver. We've worked hard to ditch all the boilerplate and replace it
with defaults, so the difference isn't much, and if we don't keep
simple helpers really simple there's not much point.

Also once you don't use simple helpers anymore I think migrating out
of drm/tiny is probably a good idea.
-Daniel

> For testing, ran GNOME and Weston with current changes in a Linux VM on
> Windows 10 with hyper-v enabled.
>
> Thanks,
> Deepak
>
> Deepak Rawat (2):
>   drm/hyperv: Add DRM driver for hyperv synthetic video device
>   MAINTAINERS: Add maintainer for hyperv video device
>
>  MAINTAINERS                       |    8 +
>  drivers/gpu/drm/tiny/Kconfig      |    9 +
>  drivers/gpu/drm/tiny/Makefile     |    1 +
>  drivers/gpu/drm/tiny/hyperv_drm.c | 1007 +++++++++++++++++++++++++++++
>  4 files changed, 1025 insertions(+)
>  create mode 100644 drivers/gpu/drm/tiny/hyperv_drm.c
>
> --
> 2.27.0
>


-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch