[PATCH 0/6] drm/fbdev-generic: Mandatory shadow buffering

[PATCH 0/6] drm/fbdev-generic: Mandatory shadow buffering

[Thomas Zimmermann]

After adding fbdev-dma and converting drivers, all users of
fbdev-generic require shadow buffering. Make it mandatory and
remove all other codepaths. This change greatly simplifies the
code for generic fbdev emulation. It will work with any driver
that supports GEM's vmap and vunmap.

The change further allows for a number of cleanups and fixes. The
flag prefer_shadow_fbdev is unused and to be removed. Probing in
fbdev-generic is now simple enough to roll back if it fails. Further
simplify the code for exporting the framebuffer's physical address.
Finally rename the symbols to follow other fbdev emulation.

Thomas Zimmermann (6):
  drm/fbdev-generic: Always use shadow buffering
  drm/fbdev-generic: Remove unused prefer_shadow_fbdev flag
  drm/fb-helper: Export drm_fb_helper_release_info()
  drm/fbdev-generic: Clean up after failed probing
  drm/fb-helper: Consolidate CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM
  drm/fbdev-generic: Rename symbols

 drivers/gpu/drm/drm_fb_helper.c     |  55 +++---
 drivers/gpu/drm/drm_fbdev_dma.c     |   9 +-
 drivers/gpu/drm/drm_fbdev_generic.c | 280 +++++++++-------------------
 drivers/gpu/drm/tiny/bochs.c        |   1 -
 drivers/gpu/drm/vmwgfx/vmwgfx_kms.c |   1 -
 include/drm/drm_fb_helper.h         |  14 +-
 include/drm/drm_mode_config.h       |   7 -
 7 files changed, 125 insertions(+), 242 deletions(-)


base-commit: ec0708e846b819c8d5b642de42448a87d7526564
-- 
2.39.2

[PATCH 1/6] drm/fbdev-generic: Always use shadow buffering

[Thomas Zimmermann]

Remove all codepaths that implement fbdev output directly on GEM
buffers. Always allocate a shadow buffer in system memory and set
up deferred I/O for mmap.

The fbdev code that operated directly on GEM buffers was used by
drivers based on GEM DMA helpers. Those drivers have been migrated
to use fbdev-dma, a dedicated fbdev emulation for DMA memory. All
remaining users of fbdev-generic require shadow buffering.

Memory management of the remaining callers uses TTM, GEM SHMEM
helpers or a variant of GEM DMA helpers that is incompatible with
fbdev-dma. Therefore remove the unused codepaths from fbdev-generic
and simplify the code.

Using a shadow buffer with deferred I/O is probably the best case
for most remaining callers. Some of the TTM-based drivers might
benefit from a dedicated fbdev emulation that operates directly on
the driver's video memory.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/drm_fbdev_generic.c | 184 +++++-----------------------
 1 file changed, 30 insertions(+), 154 deletions(-)

diff --git a/drivers/gpu/drm/drm_fbdev_generic.c b/drivers/gpu/drm/drm_fbdev_generic.c
index 4d6325e91565..e48a8e82378d 100644
--- a/drivers/gpu/drm/drm_fbdev_generic.c
+++ b/drivers/gpu/drm/drm_fbdev_generic.c
@@ -11,16 +11,6 @@
 
 #include <drm/drm_fbdev_generic.h>
 
-static bool drm_fbdev_use_shadow_fb(struct drm_fb_helper *fb_helper)
-{
-	struct drm_device *dev = fb_helper->dev;
-	struct drm_framebuffer *fb = fb_helper->fb;
-
-	return dev->mode_config.prefer_shadow_fbdev ||
-	       dev->mode_config.prefer_shadow ||
-	       fb->funcs->dirty;
-}
-
 /* @user: 1=userspace, 0=fbcon */
 static int drm_fbdev_fb_open(struct fb_info *info, int user)
 {
@@ -46,115 +36,33 @@ static int drm_fbdev_fb_release(struct fb_info *info, int user)
 static void drm_fbdev_fb_destroy(struct fb_info *info)
 {
 	struct drm_fb_helper *fb_helper = info->par;
-	void *shadow = NULL;
+	void *shadow = info->screen_buffer;
 
 	if (!fb_helper->dev)
 		return;
 
-	if (info->fbdefio)
-		fb_deferred_io_cleanup(info);
-	if (drm_fbdev_use_shadow_fb(fb_helper))
-		shadow = info->screen_buffer;
-
+	fb_deferred_io_cleanup(info);
 	drm_fb_helper_fini(fb_helper);
-
-	if (shadow)
-		vfree(shadow);
-	else if (fb_helper->buffer)
-		drm_client_buffer_vunmap(fb_helper->buffer);
-
+	vfree(shadow);
 	drm_client_framebuffer_delete(fb_helper->buffer);
-	drm_client_release(&fb_helper->client);
 
+	drm_client_release(&fb_helper->client);
 	drm_fb_helper_unprepare(fb_helper);
 	kfree(fb_helper);
 }
 
-static int drm_fbdev_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)
-{
-	struct drm_fb_helper *fb_helper = info->par;
-
-	if (drm_fbdev_use_shadow_fb(fb_helper))
-		return fb_deferred_io_mmap(info, vma);
-	else if (fb_helper->dev->driver->gem_prime_mmap)
-		return fb_helper->dev->driver->gem_prime_mmap(fb_helper->buffer->gem, vma);
-	else
-		return -ENODEV;
-}
-
-static bool drm_fbdev_use_iomem(struct fb_info *info)
-{
-	struct drm_fb_helper *fb_helper = info->par;
-	struct drm_client_buffer *buffer = fb_helper->buffer;
-
-	return !drm_fbdev_use_shadow_fb(fb_helper) && buffer->map.is_iomem;
-}
-
-static ssize_t drm_fbdev_fb_read(struct fb_info *info, char __user *buf,
-				 size_t count, loff_t *ppos)
-{
-	ssize_t ret;
-
-	if (drm_fbdev_use_iomem(info))
-		ret = drm_fb_helper_cfb_read(info, buf, count, ppos);
-	else
-		ret = drm_fb_helper_sys_read(info, buf, count, ppos);
-
-	return ret;
-}
-
-static ssize_t drm_fbdev_fb_write(struct fb_info *info, const char __user *buf,
-				  size_t count, loff_t *ppos)
-{
-	ssize_t ret;
-
-	if (drm_fbdev_use_iomem(info))
-		ret = drm_fb_helper_cfb_write(info, buf, count, ppos);
-	else
-		ret = drm_fb_helper_sys_write(info, buf, count, ppos);
-
-	return ret;
-}
-
-static void drm_fbdev_fb_fillrect(struct fb_info *info,
-				  const struct fb_fillrect *rect)
-{
-	if (drm_fbdev_use_iomem(info))
-		drm_fb_helper_cfb_fillrect(info, rect);
-	else
-		drm_fb_helper_sys_fillrect(info, rect);
-}
-
-static void drm_fbdev_fb_copyarea(struct fb_info *info,
-				  const struct fb_copyarea *area)
-{
-	if (drm_fbdev_use_iomem(info))
-		drm_fb_helper_cfb_copyarea(info, area);
-	else
-		drm_fb_helper_sys_copyarea(info, area);
-}
-
-static void drm_fbdev_fb_imageblit(struct fb_info *info,
-				   const struct fb_image *image)
-{
-	if (drm_fbdev_use_iomem(info))
-		drm_fb_helper_cfb_imageblit(info, image);
-	else
-		drm_fb_helper_sys_imageblit(info, image);
-}
-
 static const struct fb_ops drm_fbdev_fb_ops = {
 	.owner		= THIS_MODULE,
-	DRM_FB_HELPER_DEFAULT_OPS,
 	.fb_open	= drm_fbdev_fb_open,
 	.fb_release	= drm_fbdev_fb_release,
+	.fb_read	= drm_fb_helper_sys_read,
+	.fb_write	= drm_fb_helper_sys_write,
+	DRM_FB_HELPER_DEFAULT_OPS,
+	.fb_fillrect	= drm_fb_helper_sys_fillrect,
+	.fb_copyarea	= drm_fb_helper_sys_copyarea,
+	.fb_imageblit	= drm_fb_helper_sys_imageblit,
+	.fb_mmap	= fb_deferred_io_mmap,
 	.fb_destroy	= drm_fbdev_fb_destroy,
-	.fb_mmap	= drm_fbdev_fb_mmap,
-	.fb_read	= drm_fbdev_fb_read,
-	.fb_write	= drm_fbdev_fb_write,
-	.fb_fillrect	= drm_fbdev_fb_fillrect,
-	.fb_copyarea	= drm_fbdev_fb_copyarea,
-	.fb_imageblit	= drm_fbdev_fb_imageblit,
 };
 
 /*
@@ -169,7 +77,6 @@ static int drm_fbdev_fb_probe(struct drm_fb_helper *fb_helper,
 	struct drm_framebuffer *fb;
 	struct fb_info *info;
 	u32 format;
-	struct iosys_map map;
 	int ret;
 
 	drm_dbg_kms(dev, "surface width(%d), height(%d) and bpp(%d)\n",
@@ -197,44 +104,21 @@ static int drm_fbdev_fb_probe(struct drm_fb_helper *fb_helper,
 
 	drm_fb_helper_fill_info(info, fb_helper, sizes);
 
-	if (drm_fbdev_use_shadow_fb(fb_helper)) {
-		info->screen_buffer = vzalloc(info->screen_size);
-		if (!info->screen_buffer)
-			return -ENOMEM;
-		info->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST;
+	info->screen_buffer = vzalloc(info->screen_size);
+	if (!info->screen_buffer)
+		return -ENOMEM;
+	info->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST;
 
-		/* Set a default deferred I/O handler */
-		fb_helper->fbdefio.delay = HZ / 20;
-		fb_helper->fbdefio.deferred_io = drm_fb_helper_deferred_io;
+	info->fix.smem_start = page_to_phys(vmalloc_to_page(info->screen_buffer));
 
-		info->fbdefio = &fb_helper->fbdefio;
-		ret = fb_deferred_io_init(info);
-		if (ret)
-			return ret;
-	} else {
-		/* buffer is mapped for HW framebuffer */
-		ret = drm_client_buffer_vmap(fb_helper->buffer, &map);
-		if (ret)
-			return ret;
-		if (map.is_iomem) {
-			info->screen_base = map.vaddr_iomem;
-		} else {
-			info->screen_buffer = map.vaddr;
-			info->flags |= FBINFO_VIRTFB;
-		}
-
-		/*
-		 * Shamelessly leak the physical address to user-space. As
-		 * page_to_phys() is undefined for I/O memory, warn in this
-		 * case.
-		 */
-#if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
-		if (fb_helper->hint_leak_smem_start && info->fix.smem_start == 0 &&
-		    !drm_WARN_ON_ONCE(dev, map.is_iomem))
-			info->fix.smem_start =
-				page_to_phys(virt_to_page(info->screen_buffer));
-#endif
-	}
+	/* Set a default deferred I/O handler */
+	fb_helper->fbdefio.delay = HZ / 20;
+	fb_helper->fbdefio.deferred_io = drm_fb_helper_deferred_io;
+
+	info->fbdefio = &fb_helper->fbdefio;
+	ret = fb_deferred_io_init(info);
+	if (ret)
+		return ret;
 
 	return 0;
 }
@@ -318,18 +202,13 @@ static int drm_fbdev_fb_dirty(struct drm_fb_helper *helper, struct drm_clip_rect
 	struct drm_device *dev = helper->dev;
 	int ret;
 
-	if (!drm_fbdev_use_shadow_fb(helper))
-		return 0;
-
 	/* Call damage handlers only if necessary */
 	if (!(clip->x1 < clip->x2 && clip->y1 < clip->y2))
 		return 0;
 
-	if (helper->buffer) {
-		ret = drm_fbdev_damage_blit(helper, clip);
-		if (drm_WARN_ONCE(dev, ret, "Damage blitter failed: ret=%d\n", ret))
-			return ret;
-	}
+	ret = drm_fbdev_damage_blit(helper, clip);
+	if (drm_WARN_ONCE(dev, ret, "Damage blitter failed: ret=%d\n", ret))
+		return ret;
 
 	if (helper->fb->funcs->dirty) {
 		ret = helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, clip, 1);
@@ -415,12 +294,9 @@ static const struct drm_client_funcs drm_fbdev_client_funcs = {
  * suspend/resume need to call drm_fb_helper_set_suspend_unlocked() themselves.
  * Simple drivers might use drm_mode_config_helper_suspend().
  *
- * Drivers that set the dirty callback on their framebuffer will get a shadow
- * fbdev buffer that is blitted onto the real buffer. This is done in order to
- * make deferred I/O work with all kinds of buffers. A shadow buffer can be
- * requested explicitly by setting struct drm_mode_config.prefer_shadow or
- * struct drm_mode_config.prefer_shadow_fbdev to true beforehand. This is
- * required to use generic fbdev emulation with SHMEM helpers.
+ * In order to provide fixed mmap-able memory ranges, generic fbdev emulation
+ * uses a shadow buffer in system memory. The implementation blits the shadow
+ * fbdev buffer onto the real buffer in regular intervals.
  *
  * This function is safe to call even when there are no connectors present.
  * Setup will be retried on the next hotplug event.
-- 
2.39.2

[PATCH 2/6] drm/fbdev-generic: Remove unused prefer_shadow_fbdev flag

[Thomas Zimmermann]

Remove the flag prefer_shadow_fbdev from struct drm_mode_config.
Drivers set this flag to enable shadow buffering in the generic
fbdev emulation. Such shadow buffering is now mandatory, so the
flag is unused.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/tiny/bochs.c        | 1 -
 drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 1 -
 include/drm/drm_mode_config.h       | 7 -------
 3 files changed, 9 deletions(-)

diff --git a/drivers/gpu/drm/tiny/bochs.c b/drivers/gpu/drm/tiny/bochs.c
index 024346054c70..d254679a136e 100644
--- a/drivers/gpu/drm/tiny/bochs.c
+++ b/drivers/gpu/drm/tiny/bochs.c
@@ -545,7 +545,6 @@ static int bochs_kms_init(struct bochs_device *bochs)
 
 	bochs->dev->mode_config.preferred_depth = 24;
 	bochs->dev->mode_config.prefer_shadow = 0;
-	bochs->dev->mode_config.prefer_shadow_fbdev = 1;
 	bochs->dev->mode_config.quirk_addfb_prefer_host_byte_order = true;
 
 	bochs->dev->mode_config.funcs = &bochs_mode_funcs;
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
index 84d6380b9895..5162a7a12792 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
@@ -2112,7 +2112,6 @@ int vmw_kms_init(struct vmw_private *dev_priv)
 	dev->mode_config.max_width = dev_priv->texture_max_width;
 	dev->mode_config.max_height = dev_priv->texture_max_height;
 	dev->mode_config.preferred_depth = dev_priv->assume_16bpp ? 16 : 32;
-	dev->mode_config.prefer_shadow_fbdev = !dev_priv->has_mob;
 
 	drm_mode_create_suggested_offset_properties(dev);
 	vmw_kms_create_hotplug_mode_update_property(dev_priv);
diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h
index e5b053001d22..973119a9176b 100644
--- a/include/drm/drm_mode_config.h
+++ b/include/drm/drm_mode_config.h
@@ -890,13 +890,6 @@ struct drm_mode_config {
 	/* dumb ioctl parameters */
 	uint32_t preferred_depth, prefer_shadow;
 
-	/**
-	 * @prefer_shadow_fbdev:
-	 *
-	 * Hint to framebuffer emulation to prefer shadow-fb rendering.
-	 */
-	bool prefer_shadow_fbdev;
-
 	/**
 	 * @quirk_addfb_prefer_xbgr_30bpp:
 	 *
-- 
2.39.2

[PATCH 3/6] drm/fb-helper: Export drm_fb_helper_release_info()

[Thomas Zimmermann]

Export the fb_info release code as drm_fb_helper_release_info(). Will
help with cleaning up failed fbdev probing.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/drm_fb_helper.c | 33 ++++++++++++++++++++++++---------
 include/drm/drm_fb_helper.h     |  5 +++++
 2 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index a39998047f8a..7e96ed9efdb5 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -538,6 +538,29 @@ struct fb_info *drm_fb_helper_alloc_info(struct drm_fb_helper *fb_helper)
 }
 EXPORT_SYMBOL(drm_fb_helper_alloc_info);
 
+/**
+ * drm_fb_helper_release_info - release fb_info and its members
+ * @fb_helper: driver-allocated fbdev helper
+ *
+ * A helper to release fb_info and the member cmap.  Drivers do not
+ * need to release the allocated fb_info structure themselves, this is
+ * automatically done when calling drm_fb_helper_fini().
+ */
+void drm_fb_helper_release_info(struct drm_fb_helper *fb_helper)
+{
+	struct fb_info *info = fb_helper->info;
+
+	if (!info)
+		return;
+
+	fb_helper->info = NULL;
+
+	if (info->cmap.len)
+		fb_dealloc_cmap(&info->cmap);
+	framebuffer_release(info);
+}
+EXPORT_SYMBOL(drm_fb_helper_release_info);
+
 /**
  * drm_fb_helper_unregister_info - unregister fb_info framebuffer device
  * @fb_helper: driver-allocated fbdev helper, can be NULL
@@ -561,8 +584,6 @@ EXPORT_SYMBOL(drm_fb_helper_unregister_info);
  */
 void drm_fb_helper_fini(struct drm_fb_helper *fb_helper)
 {
-	struct fb_info *info;
-
 	if (!fb_helper)
 		return;
 
@@ -574,13 +595,7 @@ void drm_fb_helper_fini(struct drm_fb_helper *fb_helper)
 	cancel_work_sync(&fb_helper->resume_work);
 	cancel_work_sync(&fb_helper->damage_work);
 
-	info = fb_helper->info;
-	if (info) {
-		if (info->cmap.len)
-			fb_dealloc_cmap(&info->cmap);
-		framebuffer_release(info);
-	}
-	fb_helper->info = NULL;
+	drm_fb_helper_release_info(fb_helper);
 
 	mutex_lock(&kernel_fb_helper_lock);
 	if (!list_empty(&fb_helper->kernel_fb_list)) {
diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
index 013654de3fc5..c5822ec2fdd1 100644
--- a/include/drm/drm_fb_helper.h
+++ b/include/drm/drm_fb_helper.h
@@ -256,6 +256,7 @@ int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
 int drm_fb_helper_restore_fbdev_mode_unlocked(struct drm_fb_helper *fb_helper);
 
 struct fb_info *drm_fb_helper_alloc_info(struct drm_fb_helper *fb_helper);
+void drm_fb_helper_release_info(struct drm_fb_helper *fb_helper);
 void drm_fb_helper_unregister_info(struct drm_fb_helper *fb_helper);
 void drm_fb_helper_fill_info(struct fb_info *info,
 			     struct drm_fb_helper *fb_helper,
@@ -365,6 +366,10 @@ drm_fb_helper_alloc_info(struct drm_fb_helper *fb_helper)
 	return NULL;
 }
 
+static inline void drm_fb_helper_release_info(struct drm_fb_helper *fb_helper)
+{
+}
+
 static inline void drm_fb_helper_unregister_info(struct drm_fb_helper *fb_helper)
 {
 }
-- 
2.39.2

[PATCH 4/6] drm/fbdev-generic: Clean up after failed probing

[Thomas Zimmermann]

Clean up fbdev and client state if the probe function fails. It
used to leak allocated resources. Also reorder the individual steps
to simplify cleanup.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/drm_fbdev_generic.c | 46 ++++++++++++++++++++---------
 1 file changed, 32 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/drm_fbdev_generic.c b/drivers/gpu/drm/drm_fbdev_generic.c
index e48a8e82378d..0d08ddbe9608 100644
--- a/drivers/gpu/drm/drm_fbdev_generic.c
+++ b/drivers/gpu/drm/drm_fbdev_generic.c
@@ -7,6 +7,7 @@
 #include <drm/drm_drv.h>
 #include <drm/drm_fb_helper.h>
 #include <drm/drm_framebuffer.h>
+#include <drm/drm_gem.h>
 #include <drm/drm_print.h>
 
 #include <drm/drm_fbdev_generic.h>
@@ -74,8 +75,9 @@ static int drm_fbdev_fb_probe(struct drm_fb_helper *fb_helper,
 	struct drm_client_dev *client = &fb_helper->client;
 	struct drm_device *dev = fb_helper->dev;
 	struct drm_client_buffer *buffer;
-	struct drm_framebuffer *fb;
 	struct fb_info *info;
+	size_t screen_size;
+	void *screen_buffer;
 	u32 format;
 	int ret;
 
@@ -91,36 +93,52 @@ static int drm_fbdev_fb_probe(struct drm_fb_helper *fb_helper,
 
 	fb_helper->buffer = buffer;
 	fb_helper->fb = buffer->fb;
-	fb = buffer->fb;
+
+	screen_size = buffer->gem->size;
+	screen_buffer = vzalloc(screen_size);
+	if (!screen_buffer) {
+		ret = -ENOMEM;
+		goto err_drm_client_framebuffer_delete;
+	}
 
 	info = drm_fb_helper_alloc_info(fb_helper);
-	if (IS_ERR(info))
-		return PTR_ERR(info);
+	if (IS_ERR(info)) {
+		ret = PTR_ERR(info);
+		goto err_vfree;
+	}
+
+	drm_fb_helper_fill_info(info, fb_helper, sizes);
 
 	info->fbops = &drm_fbdev_fb_ops;
-	info->screen_size = sizes->surface_height * fb->pitches[0];
-	info->fix.smem_len = info->screen_size;
 	info->flags = FBINFO_DEFAULT;
 
-	drm_fb_helper_fill_info(info, fb_helper, sizes);
-
-	info->screen_buffer = vzalloc(info->screen_size);
-	if (!info->screen_buffer)
-		return -ENOMEM;
+	/* screen */
 	info->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST;
-
+	info->screen_size = screen_size;
+	info->screen_buffer = screen_buffer;
 	info->fix.smem_start = page_to_phys(vmalloc_to_page(info->screen_buffer));
+	info->fix.smem_len = info->screen_size;
 
-	/* Set a default deferred I/O handler */
+	/* deferred I/O */
 	fb_helper->fbdefio.delay = HZ / 20;
 	fb_helper->fbdefio.deferred_io = drm_fb_helper_deferred_io;
 
 	info->fbdefio = &fb_helper->fbdefio;
 	ret = fb_deferred_io_init(info);
 	if (ret)
-		return ret;
+		goto err_drm_fb_helper_release_info;
 
 	return 0;
+
+err_drm_fb_helper_release_info:
+	drm_fb_helper_release_info(fb_helper);
+err_vfree:
+	vfree(screen_buffer);
+err_drm_client_framebuffer_delete:
+	fb_helper->fb = NULL;
+	fb_helper->buffer = NULL;
+	drm_client_framebuffer_delete(buffer);
+	return ret;
 }
 
 static void drm_fbdev_damage_blit_real(struct drm_fb_helper *fb_helper,
-- 
2.39.2

[PATCH 5/6] drm/fb-helper: Consolidate CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM

[Thomas Zimmermann]

Consolidate all handling of CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM by
making the module parameter optional in drm_fb_helper.c.

Without the config option, modules can set smem_start in struct
fb_info for internal usage, but not export if to userspace. The
address can only be exported by enabling the option and setting
the module parameter. Also update the comment.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/drm_fb_helper.c | 22 ++++++++--------------
 drivers/gpu/drm/drm_fbdev_dma.c |  9 +--------
 include/drm/drm_fb_helper.h     |  9 ---------
 3 files changed, 9 insertions(+), 31 deletions(-)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 7e96ed9efdb5..b536b472f3ef 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -60,16 +60,17 @@ MODULE_PARM_DESC(drm_fbdev_overalloc,
  * In order to keep user-space compatibility, we want in certain use-cases
  * to keep leaking the fbdev physical address to the user-space program
  * handling the fbdev buffer.
- * This is a bad habit essentially kept into closed source opengl driver
- * that should really be moved into open-source upstream projects instead
- * of using legacy physical addresses in user space to communicate with
- * other out-of-tree kernel modules.
+ *
+ * This is a bad habit, essentially kept to support closed-source OpenGL
+ * drivers that should really be moved into open-source upstream projects
+ * instead of using legacy physical addresses in user space to communicate
+ * with other out-of-tree kernel modules.
  *
  * This module_param *should* be removed as soon as possible and be
  * considered as a broken and legacy behaviour from a modern fbdev device.
  */
-#if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
 static bool drm_leak_fbdev_smem;
+#if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
 module_param_unsafe(drm_leak_fbdev_smem, bool, 0600);
 MODULE_PARM_DESC(drm_leak_fbdev_smem,
 		 "Allow unsafe leaking fbdev physical smem address [default=false]");
@@ -1979,10 +1980,6 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper)
 		return ret;
 	}
 
-#if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
-	fb_helper->hint_leak_smem_start = drm_leak_fbdev_smem;
-#endif
-
 	/* push down into drivers */
 	ret = (*fb_helper->funcs->fb_probe)(fb_helper, &sizes);
 	if (ret < 0)
@@ -2181,11 +2178,8 @@ __drm_fb_helper_initial_config_and_unlock(struct drm_fb_helper *fb_helper)
 
 	info = fb_helper->info;
 	info->var.pixclock = 0;
-	/* Shamelessly allow physical address leaking to userspace */
-#if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
-	if (!fb_helper->hint_leak_smem_start)
-#endif
-		/* don't leak any physical addresses to userspace */
+
+	if (!drm_leak_fbdev_smem)
 		info->flags |= FBINFO_HIDE_SMEM_START;
 
 	/* Need to drop locks to avoid recursive deadlock in
diff --git a/drivers/gpu/drm/drm_fbdev_dma.c b/drivers/gpu/drm/drm_fbdev_dma.c
index cf553ac12a0f..728deffcc0d9 100644
--- a/drivers/gpu/drm/drm_fbdev_dma.c
+++ b/drivers/gpu/drm/drm_fbdev_dma.c
@@ -136,16 +136,9 @@ static int drm_fbdev_dma_helper_fb_probe(struct drm_fb_helper *fb_helper,
 		info->flags |= FBINFO_READS_FAST; /* signal caching */
 	info->screen_size = sizes->surface_height * fb->pitches[0];
 	info->screen_buffer = map.vaddr;
+	info->fix.smem_start = page_to_phys(virt_to_page(info->screen_buffer));
 	info->fix.smem_len = info->screen_size;
 
-#if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
-	/*
-	 * Shamelessly leak the physical address to user-space.
-	 */
-	if (fb_helper->hint_leak_smem_start && !info->fix.smem_start)
-		info->fix.smem_start = page_to_phys(virt_to_page(info->screen_buffer));
-#endif
-
 	return 0;
 
 err_drm_client_buffer_vunmap:
diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
index c5822ec2fdd1..72032c354a30 100644
--- a/include/drm/drm_fb_helper.h
+++ b/include/drm/drm_fb_helper.h
@@ -195,15 +195,6 @@ struct drm_fb_helper {
 	 */
 	int preferred_bpp;
 
-	/**
-	 * @hint_leak_smem_start:
-	 *
-	 * Hint to the fbdev emulation to store the framebuffer's physical
-	 * address in struct &fb_info.fix.smem_start. If the hint is unset,
-	 * the smem_start field should always be cleared to zero.
-	 */
-	bool hint_leak_smem_start;
-
 #ifdef CONFIG_FB_DEFERRED_IO
 	/**
 	 * @fbdefio:
-- 
2.39.2

[PATCH 6/6] drm/fbdev-generic: Rename symbols

[Thomas Zimmermann]

Rename symbols to match the style of other fbdev-emulation source
code. No functional changes.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/drm_fbdev_generic.c | 66 ++++++++++++++---------------
 1 file changed, 33 insertions(+), 33 deletions(-)

diff --git a/drivers/gpu/drm/drm_fbdev_generic.c b/drivers/gpu/drm/drm_fbdev_generic.c
index 0d08ddbe9608..e70e3138a78e 100644
--- a/drivers/gpu/drm/drm_fbdev_generic.c
+++ b/drivers/gpu/drm/drm_fbdev_generic.c
@@ -13,7 +13,7 @@
 #include <drm/drm_fbdev_generic.h>
 
 /* @user: 1=userspace, 0=fbcon */
-static int drm_fbdev_fb_open(struct fb_info *info, int user)
+static int drm_fbdev_generic_fb_open(struct fb_info *info, int user)
 {
 	struct drm_fb_helper *fb_helper = info->par;
 
@@ -24,7 +24,7 @@ static int drm_fbdev_fb_open(struct fb_info *info, int user)
 	return 0;
 }
 
-static int drm_fbdev_fb_release(struct fb_info *info, int user)
+static int drm_fbdev_generic_fb_release(struct fb_info *info, int user)
 {
 	struct drm_fb_helper *fb_helper = info->par;
 
@@ -34,7 +34,7 @@ static int drm_fbdev_fb_release(struct fb_info *info, int user)
 	return 0;
 }
 
-static void drm_fbdev_fb_destroy(struct fb_info *info)
+static void drm_fbdev_generic_fb_destroy(struct fb_info *info)
 {
 	struct drm_fb_helper *fb_helper = info->par;
 	void *shadow = info->screen_buffer;
@@ -52,10 +52,10 @@ static void drm_fbdev_fb_destroy(struct fb_info *info)
 	kfree(fb_helper);
 }
 
-static const struct fb_ops drm_fbdev_fb_ops = {
+static const struct fb_ops drm_fbdev_generic_fb_ops = {
 	.owner		= THIS_MODULE,
-	.fb_open	= drm_fbdev_fb_open,
-	.fb_release	= drm_fbdev_fb_release,
+	.fb_open	= drm_fbdev_generic_fb_open,
+	.fb_release	= drm_fbdev_generic_fb_release,
 	.fb_read	= drm_fb_helper_sys_read,
 	.fb_write	= drm_fb_helper_sys_write,
 	DRM_FB_HELPER_DEFAULT_OPS,
@@ -63,14 +63,14 @@ static const struct fb_ops drm_fbdev_fb_ops = {
 	.fb_copyarea	= drm_fb_helper_sys_copyarea,
 	.fb_imageblit	= drm_fb_helper_sys_imageblit,
 	.fb_mmap	= fb_deferred_io_mmap,
-	.fb_destroy	= drm_fbdev_fb_destroy,
+	.fb_destroy	= drm_fbdev_generic_fb_destroy,
 };
 
 /*
  * This function uses the client API to create a framebuffer backed by a dumb buffer.
  */
-static int drm_fbdev_fb_probe(struct drm_fb_helper *fb_helper,
-			      struct drm_fb_helper_surface_size *sizes)
+static int drm_fbdev_generic_helper_fb_probe(struct drm_fb_helper *fb_helper,
+					     struct drm_fb_helper_surface_size *sizes)
 {
 	struct drm_client_dev *client = &fb_helper->client;
 	struct drm_device *dev = fb_helper->dev;
@@ -109,7 +109,7 @@ static int drm_fbdev_fb_probe(struct drm_fb_helper *fb_helper,
 
 	drm_fb_helper_fill_info(info, fb_helper, sizes);
 
-	info->fbops = &drm_fbdev_fb_ops;
+	info->fbops = &drm_fbdev_generic_fb_ops;
 	info->flags = FBINFO_DEFAULT;
 
 	/* screen */
@@ -141,9 +141,9 @@ static int drm_fbdev_fb_probe(struct drm_fb_helper *fb_helper,
 	return ret;
 }
 
-static void drm_fbdev_damage_blit_real(struct drm_fb_helper *fb_helper,
-				       struct drm_clip_rect *clip,
-				       struct iosys_map *dst)
+static void drm_fbdev_generic_damage_blit_real(struct drm_fb_helper *fb_helper,
+					       struct drm_clip_rect *clip,
+					       struct iosys_map *dst)
 {
 	struct drm_framebuffer *fb = fb_helper->fb;
 	size_t offset = clip->y1 * fb->pitches[0];
@@ -180,8 +180,8 @@ static void drm_fbdev_damage_blit_real(struct drm_fb_helper *fb_helper,
 	}
 }
 
-static int drm_fbdev_damage_blit(struct drm_fb_helper *fb_helper,
-				 struct drm_clip_rect *clip)
+static int drm_fbdev_generic_damage_blit(struct drm_fb_helper *fb_helper,
+					 struct drm_clip_rect *clip)
 {
 	struct drm_client_buffer *buffer = fb_helper->buffer;
 	struct iosys_map map, dst;
@@ -205,7 +205,7 @@ static int drm_fbdev_damage_blit(struct drm_fb_helper *fb_helper,
 		goto out;
 
 	dst = map;
-	drm_fbdev_damage_blit_real(fb_helper, clip, &dst);
+	drm_fbdev_generic_damage_blit_real(fb_helper, clip, &dst);
 
 	drm_client_buffer_vunmap(buffer);
 
@@ -215,7 +215,8 @@ static int drm_fbdev_damage_blit(struct drm_fb_helper *fb_helper,
 	return ret;
 }
 
-static int drm_fbdev_fb_dirty(struct drm_fb_helper *helper, struct drm_clip_rect *clip)
+static int drm_fbdev_generic_helper_fb_dirty(struct drm_fb_helper *helper,
+					     struct drm_clip_rect *clip)
 {
 	struct drm_device *dev = helper->dev;
 	int ret;
@@ -224,7 +225,7 @@ static int drm_fbdev_fb_dirty(struct drm_fb_helper *helper, struct drm_clip_rect
 	if (!(clip->x1 < clip->x2 && clip->y1 < clip->y2))
 		return 0;
 
-	ret = drm_fbdev_damage_blit(helper, clip);
+	ret = drm_fbdev_generic_damage_blit(helper, clip);
 	if (drm_WARN_ONCE(dev, ret, "Damage blitter failed: ret=%d\n", ret))
 		return ret;
 
@@ -237,12 +238,12 @@ static int drm_fbdev_fb_dirty(struct drm_fb_helper *helper, struct drm_clip_rect
 	return 0;
 }
 
-static const struct drm_fb_helper_funcs drm_fb_helper_generic_funcs = {
-	.fb_probe = drm_fbdev_fb_probe,
-	.fb_dirty = drm_fbdev_fb_dirty,
+static const struct drm_fb_helper_funcs drm_fbdev_generic_helper_funcs = {
+	.fb_probe = drm_fbdev_generic_helper_fb_probe,
+	.fb_dirty = drm_fbdev_generic_helper_fb_dirty,
 };
 
-static void drm_fbdev_client_unregister(struct drm_client_dev *client)
+static void drm_fbdev_generic_client_unregister(struct drm_client_dev *client)
 {
 	struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
 
@@ -255,14 +256,14 @@ static void drm_fbdev_client_unregister(struct drm_client_dev *client)
 	}
 }
 
-static int drm_fbdev_client_restore(struct drm_client_dev *client)
+static int drm_fbdev_generic_client_restore(struct drm_client_dev *client)
 {
 	drm_fb_helper_lastclose(client->dev);
 
 	return 0;
 }
 
-static int drm_fbdev_client_hotplug(struct drm_client_dev *client)
+static int drm_fbdev_generic_client_hotplug(struct drm_client_dev *client)
 {
 	struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
 	struct drm_device *dev = client->dev;
@@ -291,11 +292,11 @@ static int drm_fbdev_client_hotplug(struct drm_client_dev *client)
 	return ret;
 }
 
-static const struct drm_client_funcs drm_fbdev_client_funcs = {
+static const struct drm_client_funcs drm_fbdev_generic_client_funcs = {
 	.owner		= THIS_MODULE,
-	.unregister	= drm_fbdev_client_unregister,
-	.restore	= drm_fbdev_client_restore,
-	.hotplug	= drm_fbdev_client_hotplug,
+	.unregister	= drm_fbdev_generic_client_unregister,
+	.restore	= drm_fbdev_generic_client_restore,
+	.hotplug	= drm_fbdev_generic_client_hotplug,
 };
 
 /**
@@ -321,8 +322,7 @@ static const struct drm_client_funcs drm_fbdev_client_funcs = {
  *
  * The fbdev is destroyed by drm_dev_unregister().
  */
-void drm_fbdev_generic_setup(struct drm_device *dev,
-			     unsigned int preferred_bpp)
+void drm_fbdev_generic_setup(struct drm_device *dev, unsigned int preferred_bpp)
 {
 	struct drm_fb_helper *fb_helper;
 	int ret;
@@ -333,15 +333,15 @@ void drm_fbdev_generic_setup(struct drm_device *dev,
 	fb_helper = kzalloc(sizeof(*fb_helper), GFP_KERNEL);
 	if (!fb_helper)
 		return;
-	drm_fb_helper_prepare(dev, fb_helper, preferred_bpp, &drm_fb_helper_generic_funcs);
+	drm_fb_helper_prepare(dev, fb_helper, preferred_bpp, &drm_fbdev_generic_helper_funcs);
 
-	ret = drm_client_init(dev, &fb_helper->client, "fbdev", &drm_fbdev_client_funcs);
+	ret = drm_client_init(dev, &fb_helper->client, "fbdev", &drm_fbdev_generic_client_funcs);
 	if (ret) {
 		drm_err(dev, "Failed to register client: %d\n", ret);
 		goto err_drm_client_init;
 	}
 
-	ret = drm_fbdev_client_hotplug(&fb_helper->client);
+	ret = drm_fbdev_generic_client_hotplug(&fb_helper->client);
 	if (ret)
 		drm_dbg_kms(dev, "client hotplug ret=%d\n", ret);
 
-- 
2.39.2

Re: [PATCH 2/6] drm/fbdev-generic: Remove unused prefer_shadow_fbdev flag

[Zack Rusin]

On Wed, 2023-03-15 at 17:14 +0100, Thomas Zimmermann wrote:
> Remove the flag prefer_shadow_fbdev from struct drm_mode_config.
> Drivers set this flag to enable shadow buffering in the generic
> fbdev emulation. Such shadow buffering is now mandatory, so the
> flag is unused.
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---
>  drivers/gpu/drm/tiny/bochs.c        | 1 -
>  drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 1 -
>  include/drm/drm_mode_config.h       | 7 -------
>  3 files changed, 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/tiny/bochs.c b/drivers/gpu/drm/tiny/bochs.c
> index 024346054c70..d254679a136e 100644
> --- a/drivers/gpu/drm/tiny/bochs.c
> +++ b/drivers/gpu/drm/tiny/bochs.c
> @@ -545,7 +545,6 @@ static int bochs_kms_init(struct bochs_device *bochs)
>  
>         bochs->dev->mode_config.preferred_depth = 24;
>         bochs->dev->mode_config.prefer_shadow = 0;
> -       bochs->dev->mode_config.prefer_shadow_fbdev = 1;
>         bochs->dev->mode_config.quirk_addfb_prefer_host_byte_order = true;
>  
>         bochs->dev->mode_config.funcs = &bochs_mode_funcs;
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> index 84d6380b9895..5162a7a12792 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> @@ -2112,7 +2112,6 @@ int vmw_kms_init(struct vmw_private *dev_priv)
>         dev->mode_config.max_width = dev_priv->texture_max_width;
>         dev->mode_config.max_height = dev_priv->texture_max_height;
>         dev->mode_config.preferred_depth = dev_priv->assume_16bpp ? 16 : 32;
> -       dev->mode_config.prefer_shadow_fbdev = !dev_priv->has_mob;
>  
>         drm_mode_create_suggested_offset_properties(dev);
>         vmw_kms_create_hotplug_mode_update_property(dev_priv);
> diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h
> index e5b053001d22..973119a9176b 100644
> --- a/include/drm/drm_mode_config.h
> +++ b/include/drm/drm_mode_config.h
> @@ -890,13 +890,6 @@ struct drm_mode_config {
>         /* dumb ioctl parameters */
>         uint32_t preferred_depth, prefer_shadow;
>  
> -       /**
> -        * @prefer_shadow_fbdev:
> -        *
> -        * Hint to framebuffer emulation to prefer shadow-fb rendering.
> -        */
> -       bool prefer_shadow_fbdev;
> -
>         /**
>          * @quirk_addfb_prefer_xbgr_30bpp:
>          *

For this one:
Reviewed-by: Zack Rusin <zackr@vmware.com>

The entire series looks great. I think it's a great cleanup:
Acked-by: Zack Rusin <zackr@vmware.com>
For the rest.

z

Re: [PATCH 2/6] drm/fbdev-generic: Remove unused prefer_shadow_fbdev flag

[Thomas Zimmermann]

[-- Attachment #1.1: Type: text/plain, Size: 3190 bytes --]

Hi

Am 16.03.23 um 03:16 schrieb Zack Rusin:
> On Wed, 2023-03-15 at 17:14 +0100, Thomas Zimmermann wrote:
>> Remove the flag prefer_shadow_fbdev from struct drm_mode_config.
>> Drivers set this flag to enable shadow buffering in the generic
>> fbdev emulation. Such shadow buffering is now mandatory, so the
>> flag is unused.
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>> ---
>>   drivers/gpu/drm/tiny/bochs.c        | 1 -
>>   drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 1 -
>>   include/drm/drm_mode_config.h       | 7 -------
>>   3 files changed, 9 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/tiny/bochs.c b/drivers/gpu/drm/tiny/bochs.c
>> index 024346054c70..d254679a136e 100644
>> --- a/drivers/gpu/drm/tiny/bochs.c
>> +++ b/drivers/gpu/drm/tiny/bochs.c
>> @@ -545,7 +545,6 @@ static int bochs_kms_init(struct bochs_device *bochs)
>>   
>>          bochs->dev->mode_config.preferred_depth = 24;
>>          bochs->dev->mode_config.prefer_shadow = 0;
>> -       bochs->dev->mode_config.prefer_shadow_fbdev = 1;
>>          bochs->dev->mode_config.quirk_addfb_prefer_host_byte_order = true;
>>   
>>          bochs->dev->mode_config.funcs = &bochs_mode_funcs;
>> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
>> b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
>> index 84d6380b9895..5162a7a12792 100644
>> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
>> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
>> @@ -2112,7 +2112,6 @@ int vmw_kms_init(struct vmw_private *dev_priv)
>>          dev->mode_config.max_width = dev_priv->texture_max_width;
>>          dev->mode_config.max_height = dev_priv->texture_max_height;
>>          dev->mode_config.preferred_depth = dev_priv->assume_16bpp ? 16 : 32;
>> -       dev->mode_config.prefer_shadow_fbdev = !dev_priv->has_mob;
>>   
>>          drm_mode_create_suggested_offset_properties(dev);
>>          vmw_kms_create_hotplug_mode_update_property(dev_priv);
>> diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h
>> index e5b053001d22..973119a9176b 100644
>> --- a/include/drm/drm_mode_config.h
>> +++ b/include/drm/drm_mode_config.h
>> @@ -890,13 +890,6 @@ struct drm_mode_config {
>>          /* dumb ioctl parameters */
>>          uint32_t preferred_depth, prefer_shadow;
>>   
>> -       /**
>> -        * @prefer_shadow_fbdev:
>> -        *
>> -        * Hint to framebuffer emulation to prefer shadow-fb rendering.
>> -        */
>> -       bool prefer_shadow_fbdev;
>> -
>>          /**
>>           * @quirk_addfb_prefer_xbgr_30bpp:
>>           *
> 
> For this one:
> Reviewed-by: Zack Rusin <zackr@vmware.com>
> 
> The entire series looks great. I think it's a great cleanup:
> Acked-by: Zack Rusin <zackr@vmware.com>
> For the rest.

Thanks a lot!

> 
> z
> 

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

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Re: [PATCH 1/6] drm/fbdev-generic: Always use shadow buffering

[Javier Martinez Canillas]

Thomas Zimmermann <tzimmermann@suse.de> writes:

Hello Thomas,

> Remove all codepaths that implement fbdev output directly on GEM
> buffers. Always allocate a shadow buffer in system memory and set
> up deferred I/O for mmap.
>
> The fbdev code that operated directly on GEM buffers was used by
> drivers based on GEM DMA helpers. Those drivers have been migrated
> to use fbdev-dma, a dedicated fbdev emulation for DMA memory. All
> remaining users of fbdev-generic require shadow buffering.
>
> Memory management of the remaining callers uses TTM, GEM SHMEM
> helpers or a variant of GEM DMA helpers that is incompatible with
> fbdev-dma. Therefore remove the unused codepaths from fbdev-generic
> and simplify the code.
>
> Using a shadow buffer with deferred I/O is probably the best case
> for most remaining callers. Some of the TTM-based drivers might
> benefit from a dedicated fbdev emulation that operates directly on
> the driver's video memory.
>

But it's questionable if that would be useful due the limited ammount of
video memory that most of the devices using TTM-based drivers have, right?

> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---

It's much cleaner indeed to have fbdev-dma separated from fbdev-generic.

Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat

Re: [PATCH 2/6] drm/fbdev-generic: Remove unused prefer_shadow_fbdev flag

[Javier Martinez Canillas]

Thomas Zimmermann <tzimmermann@suse.de> writes:

> Remove the flag prefer_shadow_fbdev from struct drm_mode_config.
> Drivers set this flag to enable shadow buffering in the generic
> fbdev emulation. Such shadow buffering is now mandatory, so the
> flag is unused.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---

Surprised that there are only two drivers setting the flag. I guess isn't
a common case to have prefer_shadow == 0 and prefer_shadow_fbdev == 1.

Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat

Re: [PATCH 3/6] drm/fb-helper: Export drm_fb_helper_release_info()

[Javier Martinez Canillas]

Thomas Zimmermann <tzimmermann@suse.de> writes:

> Export the fb_info release code as drm_fb_helper_release_info(). Will
> help with cleaning up failed fbdev probing.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---

Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat

Re: [PATCH 1/6] drm/fbdev-generic: Always use shadow buffering

[Thomas Zimmermann]

[-- Attachment #1.1: Type: text/plain, Size: 2220 bytes --]

Hi Javier

Am 17.03.23 um 12:47 schrieb Javier Martinez Canillas:
> Thomas Zimmermann <tzimmermann@suse.de> writes:
> 
> Hello Thomas,
> 
>> Remove all codepaths that implement fbdev output directly on GEM
>> buffers. Always allocate a shadow buffer in system memory and set
>> up deferred I/O for mmap.
>>
>> The fbdev code that operated directly on GEM buffers was used by
>> drivers based on GEM DMA helpers. Those drivers have been migrated
>> to use fbdev-dma, a dedicated fbdev emulation for DMA memory. All
>> remaining users of fbdev-generic require shadow buffering.
>>
>> Memory management of the remaining callers uses TTM, GEM SHMEM
>> helpers or a variant of GEM DMA helpers that is incompatible with
>> fbdev-dma. Therefore remove the unused codepaths from fbdev-generic
>> and simplify the code.
>>
>> Using a shadow buffer with deferred I/O is probably the best case
>> for most remaining callers. Some of the TTM-based drivers might
>> benefit from a dedicated fbdev emulation that operates directly on
>> the driver's video memory.
>>
> 
> But it's questionable if that would be useful due the limited ammount of
> video memory that most of the devices using TTM-based drivers have, right?

Right. The main reason for using VRAM directly is performance. I've seen 
complains about the console performance with nouveau after they switched 
to fbdev-generic. Some drivers and/or hardware had acceleration for the 
console that could also be utilized. Of course, this requires a certain 
amount of video ram dedicated to the fbdev layer.

The other reason is the VGA swicheroo, which is currently hacked into 
the fbdev helpers. Only a few drivers need it, so having it in separate 
fbbev emulation for each driver would be nice.

Best regards
Thomas

> 
>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>> ---
> 
> It's much cleaner indeed to have fbdev-dma separated from fbdev-generic.
> 
> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
> 

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

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Re: [PATCH 4/6] drm/fbdev-generic: Clean up after failed probing

[Javier Martinez Canillas]

Thomas Zimmermann <tzimmermann@suse.de> writes:

[...]

> @@ -91,36 +93,52 @@ static int drm_fbdev_fb_probe(struct drm_fb_helper *fb_helper,
>  
>  	fb_helper->buffer = buffer;
>  	fb_helper->fb = buffer->fb;
> -	fb = buffer->fb;
> +
> +	screen_size = buffer->gem->size;

[...]

> -	info->screen_size = sizes->surface_height * fb->pitches[0];

[...]

I wonder if this change should be a separate patch? I know that it should
be the same size but still feels like an unrelated change that deserves a
different patch and description.

[...]
  
> -	/* Set a default deferred I/O handler */
> +	/* deferred I/O */

I would either have it as /* Generic fbdev deferred I/O handler */ or just
remove the comment. I understand why you are removing the "default", since
implies that drivers can change the handler and that's not the case here.

But I think that just leaving the "deferred I/O" comment there doesn't say
that much.

Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat

Re: [PATCH 5/6] drm/fb-helper: Consolidate CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM

[Javier Martinez Canillas]

Thomas Zimmermann <tzimmermann@suse.de> writes:

> Consolidate all handling of CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM by
> making the module parameter optional in drm_fb_helper.c.
>
> Without the config option, modules can set smem_start in struct
> fb_info for internal usage, but not export if to userspace. The
> address can only be exported by enabling the option and setting
> the module parameter. Also update the comment.
>

I was going to ask at what point we could just get rid of this Kconfig
symbol since it already depends on EXPERT anyways so most distros will
not enable it.

But I looked then and noticed that it was added just a few years ago in
commit 4be9bd10e22d "(drm/fb_helper: Allow leaking fbdev smem_start"),
so it seems that people still need that :(

> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---

The patch looks good to me.

Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat

Re: [PATCH 6/6] drm/fbdev-generic: Rename symbols

[Javier Martinez Canillas]

Thomas Zimmermann <tzimmermann@suse.de> writes:

> Rename symbols to match the style of other fbdev-emulation source
> code. No functional changes.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---

Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat

Re: [PATCH 5/6] drm/fb-helper: Consolidate CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM

[Thomas Zimmermann]

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Hi

Am 17.03.23 um 13:39 schrieb Javier Martinez Canillas:
> Thomas Zimmermann <tzimmermann@suse.de> writes:
> 
>> Consolidate all handling of CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM by
>> making the module parameter optional in drm_fb_helper.c.
>>
>> Without the config option, modules can set smem_start in struct
>> fb_info for internal usage, but not export if to userspace. The
>> address can only be exported by enabling the option and setting
>> the module parameter. Also update the comment.
>>
> 
> I was going to ask at what point we could just get rid of this Kconfig
> symbol since it already depends on EXPERT anyways so most distros will
> not enable it.
> 
> But I looked then and noticed that it was added just a few years ago in
> commit 4be9bd10e22d "(drm/fb_helper: Allow leaking fbdev smem_start"),
> so it seems that people still need that :(

I don't even know which userspace drivers need this symbol. Probably 
something on Android.

Best regards
Thomas

> 
>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>> ---
> 
> The patch looks good to me.
> 
> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
> 

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

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Re: [PATCH 5/6] drm/fb-helper: Consolidate CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM

[Maxime Ripard]

On Fri, Mar 17, 2023 at 01:51:42PM +0100, Thomas Zimmermann wrote:
> Hi
> 
> Am 17.03.23 um 13:39 schrieb Javier Martinez Canillas:
> > Thomas Zimmermann <tzimmermann@suse.de> writes:
> > 
> > > Consolidate all handling of CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM by
> > > making the module parameter optional in drm_fb_helper.c.
> > > 
> > > Without the config option, modules can set smem_start in struct
> > > fb_info for internal usage, but not export if to userspace. The
> > > address can only be exported by enabling the option and setting
> > > the module parameter. Also update the comment.
> > > 
> > 
> > I was going to ask at what point we could just get rid of this Kconfig
> > symbol since it already depends on EXPERT anyways so most distros will
> > not enable it.
> > 
> > But I looked then and noticed that it was added just a few years ago in
> > commit 4be9bd10e22d "(drm/fb_helper: Allow leaking fbdev smem_start"),
> > so it seems that people still need that :(
> 
> I don't even know which userspace drivers need this symbol. Probably
> something on Android.

At least the Mali (utgard) user-space stack uses it, including on
"regular" distributions.

I don't know about newest Mali generations.

Maxime

Re: [PATCH 5/6] drm/fb-helper: Consolidate CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM

[Thomas Zimmermann]

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Hi

Am 17.03.23 um 16:11 schrieb Maxime Ripard:
> On Fri, Mar 17, 2023 at 01:51:42PM +0100, Thomas Zimmermann wrote:
>> Hi
>>
>> Am 17.03.23 um 13:39 schrieb Javier Martinez Canillas:
>>> Thomas Zimmermann <tzimmermann@suse.de> writes:
>>>
>>>> Consolidate all handling of CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM by
>>>> making the module parameter optional in drm_fb_helper.c.
>>>>
>>>> Without the config option, modules can set smem_start in struct
>>>> fb_info for internal usage, but not export if to userspace. The
>>>> address can only be exported by enabling the option and setting
>>>> the module parameter. Also update the comment.
>>>>
>>>
>>> I was going to ask at what point we could just get rid of this Kconfig
>>> symbol since it already depends on EXPERT anyways so most distros will
>>> not enable it.
>>>
>>> But I looked then and noticed that it was added just a few years ago in
>>> commit 4be9bd10e22d "(drm/fb_helper: Allow leaking fbdev smem_start"),
>>> so it seems that people still need that :(
>>
>> I don't even know which userspace drivers need this symbol. Probably
>> something on Android.
> 
> At least the Mali (utgard) user-space stack uses it, including on
> "regular" distributions.

Does this use the lima kernel driver?

Best regards
Thomas

> 
> I don't know about newest Mali generations.
> 
> Maxime

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

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Re: [PATCH 5/6] drm/fb-helper: Consolidate CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM

[Maxime Ripard]

On Fri, Mar 17, 2023 at 05:08:47PM +0100, Thomas Zimmermann wrote:
> Hi
> 
> Am 17.03.23 um 16:11 schrieb Maxime Ripard:
> > On Fri, Mar 17, 2023 at 01:51:42PM +0100, Thomas Zimmermann wrote:
> > > Hi
> > > 
> > > Am 17.03.23 um 13:39 schrieb Javier Martinez Canillas:
> > > > Thomas Zimmermann <tzimmermann@suse.de> writes:
> > > > 
> > > > > Consolidate all handling of CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM by
> > > > > making the module parameter optional in drm_fb_helper.c.
> > > > > 
> > > > > Without the config option, modules can set smem_start in struct
> > > > > fb_info for internal usage, but not export if to userspace. The
> > > > > address can only be exported by enabling the option and setting
> > > > > the module parameter. Also update the comment.
> > > > > 
> > > > 
> > > > I was going to ask at what point we could just get rid of this Kconfig
> > > > symbol since it already depends on EXPERT anyways so most distros will
> > > > not enable it.
> > > > 
> > > > But I looked then and noticed that it was added just a few years ago in
> > > > commit 4be9bd10e22d "(drm/fb_helper: Allow leaking fbdev smem_start"),
> > > > so it seems that people still need that :(
> > > 
> > > I don't even know which userspace drivers need this symbol. Probably
> > > something on Android.
> > 
> > At least the Mali (utgard) user-space stack uses it, including on
> > "regular" distributions.
> 
> Does this use the lima kernel driver?

No, I meant the ARM proprietary blobs

Re: [PATCH 4/6] drm/fbdev-generic: Clean up after failed probing

[Thomas Zimmermann]

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Hi Javier

Am 17.03.23 um 13:24 schrieb Javier Martinez Canillas:
> Thomas Zimmermann <tzimmermann@suse.de> writes:
> 
> [...]
> 
>> @@ -91,36 +93,52 @@ static int drm_fbdev_fb_probe(struct drm_fb_helper *fb_helper,
>>   
>>   	fb_helper->buffer = buffer;
>>   	fb_helper->fb = buffer->fb;
>> -	fb = buffer->fb;
>> +
>> +	screen_size = buffer->gem->size;
> 
> [...]
> 
>> -	info->screen_size = sizes->surface_height * fb->pitches[0];
> 
> [...]
> 
> I wonder if this change should be a separate patch? I know that it should
> be the same size but still feels like an unrelated change that deserves a
> different patch and description.

This comment made me look up the exact meaning if screen_size, which is 
"Amount of ioremapped VRAM or 0". [1] Other drivers with shadow buffers 
(udlfb, metronomefb) apparently don't set this field. So the generic 
fbdev probably shouldn't either. The size of the video memory (physical 
or shadowed) in in fix.smem_len. [2] From grep'ing through the source 
code, it's not clear to me why screen_size exists in the first place.

Best regards
Thomas

[1] https://elixir.bootlin.com/linux/latest/source/include/linux/fb.h#L494
[2] 
https://elixir.bootlin.com/linux/latest/source/include/uapi/linux/fb.h#L161

> 
> [...]
>    
>> -	/* Set a default deferred I/O handler */
>> +	/* deferred I/O */
> 
> I would either have it as /* Generic fbdev deferred I/O handler */ or just
> remove the comment. I understand why you are removing the "default", since
> implies that drivers can change the handler and that's not the case here.
> 
> But I think that just leaving the "deferred I/O" comment there doesn't say
> that much.
> 
> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
> 

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

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