[PATCH v2 4/4] drm/i915: Implement fbdev emulation as in-kernel client

From: Thomas Zimmermann <tzimmermann@suse.de>
To: jani.nikula@linux.intel.com, joonas.lahtinen@linux.intel.com,
	rodrigo.vivi@intel.com, tvrtko.ursulin@linux.intel.com,
	ville.syrjala@linux.intel.com, imre.deak@intel.com,
	tejas.upadhyay@intel.com, javierm@redhat.com, airlied@gmail.com,
	daniel@ffwll.ch
Cc: intel-gfx@lists.freedesktop.org,
	Thomas Zimmermann <tzimmermann@suse.de>,
	dri-devel@lists.freedesktop.org
Subject: [PATCH v2 4/4] drm/i915: Implement fbdev emulation as in-kernel client
Date: Wed, 13 Sep 2023 16:58:44 +0200	[thread overview]
Message-ID: <20230913150425.5742-5-tzimmermann@suse.de> (raw)
In-Reply-To: <20230913150425.5742-1-tzimmermann@suse.de>

Replace all code that initializes or releases fbdev emulation
throughout the driver. Instead initialize the fbdev client by a
single call to i915_fbdev_setup() after i915 has registered its
DRM device. Just like similar code in other drivers, i915 fbdev
emulation now acts as a regular DRM client.

The fbdev client setup consists of the initial preparation and the
hot-plugging of the display. The latter creates the fbdev device
and sets up the fbdev framebuffer. The setup performs display
hot-plugging once. If no display can be detected, DRM probe helpers
re-run the detection on each hotplug event.

A call to drm_dev_unregister() releases the client automatically.
No further action is required within i915. If the fbdev framebuffer
has been fully set up, struct fb_ops.fb_destroy implements the
release. For partially initialized emulation, the fbdev client
reverts the initial setup.

v2:
	* let drm_client_register() handle initial hotplug
	* fix driver name in error message (Jani)
	* fix non-fbdev build (kernel test robot)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/i915/display/intel_display.c  |   1 -
 .../drm/i915/display/intel_display_driver.c   |  18 --
 drivers/gpu/drm/i915/display/intel_fbdev.c    | 182 ++++++++----------
 drivers/gpu/drm/i915/display/intel_fbdev.h    |  20 +-
 drivers/gpu/drm/i915/i915_driver.c            |   2 +
 5 files changed, 84 insertions(+), 139 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 83e1bc858b9fb..64578f991f41d 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -81,7 +81,6 @@
 #include "intel_dvo.h"
 #include "intel_fb.h"
 #include "intel_fbc.h"
-#include "intel_fbdev.h"
 #include "intel_fdi.h"
 #include "intel_fifo_underrun.h"
 #include "intel_frontbuffer.h"
diff --git a/drivers/gpu/drm/i915/display/intel_display_driver.c b/drivers/gpu/drm/i915/display/intel_display_driver.c
index 0650c0ed30a0c..7f0d6dbc47cae 100644
--- a/drivers/gpu/drm/i915/display/intel_display_driver.c
+++ b/drivers/gpu/drm/i915/display/intel_display_driver.c
@@ -364,10 +364,6 @@ int intel_display_driver_probe(struct drm_i915_private *i915)
 
 	intel_overlay_setup(i915);
 
-	ret = intel_fbdev_init(&i915->drm);
-	if (ret)
-		return ret;
-
 	/* Only enable hotplug handling once the fbdev is fully set up. */
 	intel_hpd_init(i915);
 	intel_hpd_poll_disable(i915);
@@ -390,16 +386,6 @@ void intel_display_driver_register(struct drm_i915_private *i915)
 
 	intel_display_debugfs_register(i915);
 
-	/*
-	 * Some ports require correctly set-up hpd registers for
-	 * detection to work properly (leading to ghost connected
-	 * connector status), e.g. VGA on gm45.  Hence we can only set
-	 * up the initial fbdev config after hpd irqs are fully
-	 * enabled. We do it last so that the async config cannot run
-	 * before the connectors are registered.
-	 */
-	intel_fbdev_initial_config_async(i915);
-
 	/*
 	 * We need to coordinate the hotplugs with the asynchronous
 	 * fbdev configuration, for which we use the
@@ -440,9 +426,6 @@ void intel_display_driver_remove_noirq(struct drm_i915_private *i915)
 	 */
 	intel_hpd_poll_fini(i915);
 
-	/* poll work can call into fbdev, hence clean that up afterwards */
-	intel_fbdev_fini(i915);
-
 	intel_unregister_dsm_handler();
 
 	/* flush any delayed tasks or pending work */
@@ -479,7 +462,6 @@ void intel_display_driver_unregister(struct drm_i915_private *i915)
 	if (!HAS_DISPLAY(i915))
 		return;
 
-	intel_fbdev_unregister(i915);
 	intel_audio_deinit(i915);
 
 	/*
diff --git a/drivers/gpu/drm/i915/display/intel_fbdev.c b/drivers/gpu/drm/i915/display/intel_fbdev.c
index 31e8275a70fea..8a13909d3f0b2 100644
--- a/drivers/gpu/drm/i915/display/intel_fbdev.c
+++ b/drivers/gpu/drm/i915/display/intel_fbdev.c
@@ -24,7 +24,6 @@
  *     David Airlie
  */
 
-#include <linux/async.h>
 #include <linux/console.h>
 #include <linux/delay.h>
 #include <linux/errno.h>
@@ -39,6 +38,7 @@
 #include <linux/vga_switcheroo.h>
 
 #include <drm/drm_crtc.h>
+#include <drm/drm_crtc_helper.h>
 #include <drm/drm_fb_helper.h>
 #include <drm/drm_fourcc.h>
 #include <drm/drm_gem_framebuffer_helper.h>
@@ -58,7 +58,6 @@ struct intel_fbdev {
 	struct intel_framebuffer *fb;
 	struct i915_vma *vma;
 	unsigned long vma_flags;
-	async_cookie_t cookie;
 	int preferred_bpp;
 
 	/* Whether or not fbdev hpd processing is temporarily suspended */
@@ -135,6 +134,26 @@ static int intel_fbdev_mmap(struct fb_info *info, struct vm_area_struct *vma)
 	return i915_gem_fb_mmap(obj, vma);
 }
 
+static void intel_fbdev_fb_destroy(struct fb_info *info)
+{
+	struct drm_fb_helper *fb_helper = info->par;
+	struct intel_fbdev *ifbdev = container_of(fb_helper, struct intel_fbdev, helper);
+
+	drm_fb_helper_fini(&ifbdev->helper);
+
+	/*
+	 * We rely on the object-free to release the VMA pinning for
+	 * the info->screen_base mmaping. Leaking the VMA is simpler than
+	 * trying to rectify all the possible error paths leading here.
+	 */
+	intel_unpin_fb_vma(ifbdev->vma, ifbdev->vma_flags);
+	drm_framebuffer_remove(&ifbdev->fb->base);
+
+	drm_client_release(&fb_helper->client);
+	drm_fb_helper_unprepare(&ifbdev->helper);
+	kfree(ifbdev);
+}
+
 static const struct fb_ops intelfb_ops = {
 	.owner = THIS_MODULE,
 	__FB_DEFAULT_DEFERRED_OPS_RDWR(intel_fbdev),
@@ -144,6 +163,7 @@ static const struct fb_ops intelfb_ops = {
 	.fb_pan_display = intel_fbdev_pan_display,
 	__FB_DEFAULT_DEFERRED_OPS_DRAW(intel_fbdev),
 	.fb_mmap = intel_fbdev_mmap,
+	.fb_destroy = intel_fbdev_fb_destroy,
 };
 
 static int intelfb_alloc(struct drm_fb_helper *helper,
@@ -212,7 +232,6 @@ static int intelfb_create(struct drm_fb_helper *helper,
 	struct intel_framebuffer *intel_fb = ifbdev->fb;
 	struct drm_device *dev = helper->dev;
 	struct drm_i915_private *dev_priv = to_i915(dev);
-	struct pci_dev *pdev = to_pci_dev(dev_priv->drm.dev);
 	struct i915_ggtt *ggtt = to_gt(dev_priv)->ggtt;
 	const struct i915_gtt_view view = {
 		.type = I915_GTT_VIEW_NORMAL,
@@ -337,7 +356,7 @@ static int intelfb_create(struct drm_fb_helper *helper,
 	ifbdev->vma_flags = flags;
 
 	intel_runtime_pm_put(&dev_priv->runtime_pm, wakeref);
-	vga_switcheroo_client_fb_set(pdev, info);
+
 	return 0;
 
 out_unpin:
@@ -363,26 +382,6 @@ static const struct drm_fb_helper_funcs intel_fb_helper_funcs = {
 	.fb_dirty = intelfb_dirty,
 };
 
-static void intel_fbdev_destroy(struct intel_fbdev *ifbdev)
-{
-	/* We rely on the object-free to release the VMA pinning for
-	 * the info->screen_base mmaping. Leaking the VMA is simpler than
-	 * trying to rectify all the possible error paths leading here.
-	 */
-
-	drm_fb_helper_fini(&ifbdev->helper);
-
-	if (ifbdev->vma)
-		intel_unpin_fb_vma(ifbdev->vma, ifbdev->vma_flags);
-
-	if (ifbdev->fb)
-		drm_framebuffer_remove(&ifbdev->fb->base);
-
-	drm_client_release(&ifbdev->helper.client);
-	drm_fb_helper_unprepare(&ifbdev->helper);
-	kfree(ifbdev);
-}
-
 /*
  * Build an intel_fbdev struct using a BIOS allocated framebuffer, if possible.
  * The core display code will have read out the current plane configuration,
@@ -546,16 +545,6 @@ static void intel_fbdev_suspend_worker(struct work_struct *work)
 				true);
 }
 
-static void intel_fbdev_sync(struct intel_fbdev *ifbdev)
-{
-	if (!ifbdev->cookie)
-		return;
-
-	/* Only serialises with all preceding async calls, hence +1 */
-	async_synchronize_cookie(ifbdev->cookie + 1);
-	ifbdev->cookie = 0;
-}
-
 /* Suspends/resumes fbdev processing of incoming HPD events. When resuming HPD
  * processing, fbdev will perform a full connector reprobe if a hotplug event
  * was received while HPD was suspended.
@@ -646,8 +635,6 @@ static void intel_fbdev_output_poll_changed(struct drm_device *dev)
 	if (!ifbdev)
 		return;
 
-	intel_fbdev_sync(ifbdev);
-
 	mutex_lock(&ifbdev->hpd_lock);
 	send_hpd = !ifbdev->hpd_suspended;
 	ifbdev->hpd_waiting = true;
@@ -664,7 +651,6 @@ static void intel_fbdev_restore_mode(struct drm_i915_private *dev_priv)
 	if (!ifbdev)
 		return;
 
-	intel_fbdev_sync(ifbdev);
 	if (!ifbdev->vma)
 		return;
 
@@ -677,7 +663,20 @@ static void intel_fbdev_restore_mode(struct drm_i915_private *dev_priv)
  */
 
 static void intel_fbdev_client_unregister(struct drm_client_dev *client)
-{ }
+{
+	struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
+	struct drm_device *dev = fb_helper->dev;
+	struct pci_dev *pdev = to_pci_dev(dev->dev);
+
+	if (fb_helper->info) {
+		vga_switcheroo_client_fb_set(pdev, NULL);
+		drm_fb_helper_unregister_info(fb_helper);
+	} else {
+		drm_fb_helper_unprepare(fb_helper);
+		drm_client_release(&fb_helper->client);
+		kfree(fb_helper);
+	}
+}
 
 static int intel_fbdev_client_restore(struct drm_client_dev *client)
 {
@@ -691,9 +690,36 @@ static int intel_fbdev_client_restore(struct drm_client_dev *client)
 
 static int intel_fbdev_client_hotplug(struct drm_client_dev *client)
 {
-	intel_fbdev_output_poll_changed(client->dev);
+	struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
+	struct drm_device *dev = client->dev;
+	struct pci_dev *pdev = to_pci_dev(dev->dev);
+	int ret;
+
+	if (dev->fb_helper) {
+		intel_fbdev_output_poll_changed(dev);
+		return 0;
+	}
+
+	ret = drm_fb_helper_init(dev, fb_helper);
+	if (ret)
+		goto err_drm_err;
+
+	if (!drm_drv_uses_atomic_modeset(dev))
+		drm_helper_disable_unused_functions(dev);
+
+	ret = drm_fb_helper_initial_config(fb_helper);
+	if (ret)
+		goto err_drm_fb_helper_fini;
+
+	vga_switcheroo_client_fb_set(pdev, fb_helper->info);
 
 	return 0;
+
+err_drm_fb_helper_fini:
+	drm_fb_helper_fini(fb_helper);
+err_drm_err:
+	drm_err(dev, "Failed to setup i915 fbdev emulation (ret=%d)\n", ret);
+	return ret;
 }
 
 static const struct drm_client_funcs intel_fbdev_client_funcs = {
@@ -703,22 +729,23 @@ static const struct drm_client_funcs intel_fbdev_client_funcs = {
 	.hotplug	= intel_fbdev_client_hotplug,
 };
 
-int intel_fbdev_init(struct drm_device *dev)
+void intel_fbdev_setup(struct drm_i915_private *dev_priv)
 {
-	struct drm_i915_private *dev_priv = to_i915(dev);
+	struct drm_device *dev = &dev_priv->drm;
 	struct intel_fbdev *ifbdev;
 	int ret;
 
 	if (drm_WARN_ON(dev, !HAS_DISPLAY(dev_priv)))
-		return -ENODEV;
-
-	ifbdev = kzalloc(sizeof(struct intel_fbdev), GFP_KERNEL);
-	if (ifbdev == NULL)
-		return -ENOMEM;
+		return;
 
-	mutex_init(&ifbdev->hpd_lock);
+	ifbdev = kzalloc(sizeof(*ifbdev), GFP_KERNEL);
+	if (!ifbdev)
+		return;
 	drm_fb_helper_prepare(dev, &ifbdev->helper, 32, &intel_fb_helper_funcs);
 
+	dev_priv->display.fbdev.fbdev = ifbdev;
+	INIT_WORK(&dev_priv->display.fbdev.suspend_work, intel_fbdev_suspend_worker);
+	mutex_init(&ifbdev->hpd_lock);
 	if (intel_fbdev_init_bios(dev, ifbdev))
 		ifbdev->helper.preferred_bpp = ifbdev->preferred_bpp;
 	else
@@ -726,68 +753,19 @@ int intel_fbdev_init(struct drm_device *dev)
 
 	ret = drm_client_init(dev, &ifbdev->helper.client, "i915-fbdev",
 			      &intel_fbdev_client_funcs);
-	if (ret)
+	if (ret) {
+		drm_err(dev, "Failed to register client: %d\n", ret);
 		goto err_drm_fb_helper_unprepare;
+	}
 
-	ret = drm_fb_helper_init(dev, &ifbdev->helper);
-	if (ret)
-		goto err_drm_client_release;
-
-	dev_priv->display.fbdev.fbdev = ifbdev;
-	INIT_WORK(&dev_priv->display.fbdev.suspend_work, intel_fbdev_suspend_worker);
+	drm_client_register(&ifbdev->helper.client);
 
-	return 0;
+	return;
 
-err_drm_client_release:
-	drm_client_release(&ifbdev->helper.client);
 err_drm_fb_helper_unprepare:
 	drm_fb_helper_unprepare(&ifbdev->helper);
+	mutex_destroy(&ifbdev->hpd_lock);
 	kfree(ifbdev);
-	return ret;
-}
-
-static void intel_fbdev_initial_config(void *data, async_cookie_t cookie)
-{
-	struct intel_fbdev *ifbdev = data;
-
-	/* Due to peculiar init order wrt to hpd handling this is separate. */
-	if (drm_fb_helper_initial_config(&ifbdev->helper))
-		intel_fbdev_unregister(to_i915(ifbdev->helper.dev));
-}
-
-void intel_fbdev_initial_config_async(struct drm_i915_private *dev_priv)
-{
-	struct intel_fbdev *ifbdev = dev_priv->display.fbdev.fbdev;
-
-	if (!ifbdev)
-		return;
-
-	ifbdev->cookie = async_schedule(intel_fbdev_initial_config, ifbdev);
-}
-
-void intel_fbdev_unregister(struct drm_i915_private *dev_priv)
-{
-	struct intel_fbdev *ifbdev = dev_priv->display.fbdev.fbdev;
-
-	if (!ifbdev)
-		return;
-
-	intel_fbdev_set_suspend(&dev_priv->drm, FBINFO_STATE_SUSPENDED, true);
-
-	if (!current_is_async())
-		intel_fbdev_sync(ifbdev);
-
-	drm_fb_helper_unregister_info(&ifbdev->helper);
-}
-
-void intel_fbdev_fini(struct drm_i915_private *dev_priv)
-{
-	struct intel_fbdev *ifbdev = fetch_and_zero(&dev_priv->display.fbdev.fbdev);
-
-	if (!ifbdev)
-		return;
-
-	intel_fbdev_destroy(ifbdev);
 }
 
 struct intel_framebuffer *intel_fbdev_framebuffer(struct intel_fbdev *fbdev)
diff --git a/drivers/gpu/drm/i915/display/intel_fbdev.h b/drivers/gpu/drm/i915/display/intel_fbdev.h
index 8c953f102ba22..08de2d5b34338 100644
--- a/drivers/gpu/drm/i915/display/intel_fbdev.h
+++ b/drivers/gpu/drm/i915/display/intel_fbdev.h
@@ -14,27 +14,11 @@ struct intel_fbdev;
 struct intel_framebuffer;
 
 #ifdef CONFIG_DRM_FBDEV_EMULATION
-int intel_fbdev_init(struct drm_device *dev);
-void intel_fbdev_initial_config_async(struct drm_i915_private *dev_priv);
-void intel_fbdev_unregister(struct drm_i915_private *dev_priv);
-void intel_fbdev_fini(struct drm_i915_private *dev_priv);
+void intel_fbdev_setup(struct drm_i915_private *dev_priv);
 void intel_fbdev_set_suspend(struct drm_device *dev, int state, bool synchronous);
 struct intel_framebuffer *intel_fbdev_framebuffer(struct intel_fbdev *fbdev);
 #else
-static inline int intel_fbdev_init(struct drm_device *dev)
-{
-	return 0;
-}
-
-static inline void intel_fbdev_initial_config_async(struct drm_i915_private *dev_priv)
-{
-}
-
-static inline void intel_fbdev_unregister(struct drm_i915_private *dev_priv)
-{
-}
-
-static inline void intel_fbdev_fini(struct drm_i915_private *dev_priv)
+static inline void intel_fbdev_setup(struct drm_i915_private *dev_priv)
 {
 }
 
diff --git a/drivers/gpu/drm/i915/i915_driver.c b/drivers/gpu/drm/i915/i915_driver.c
index 14aa863dca60c..200ed23a0d6f4 100644
--- a/drivers/gpu/drm/i915/i915_driver.c
+++ b/drivers/gpu/drm/i915/i915_driver.c
@@ -816,6 +816,8 @@ int i915_driver_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 
 	i915->do_release = true;
 
+	intel_fbdev_setup(i915);
+
 	return 0;
 
 out_cleanup_gem:
-- 
2.42.0

