The efifb and simplefb drivers just render to a pre-allocated frame buffer
and rely on the display hardware being initialized before the kernel boots.
But if another driver already probed correctly and registered a fbdev, the
generic drivers shouldn't be probed since an actual driver for the display
hardware is already present.
This is more likely to occur after commit d391c5827107 ("drivers/firmware:
move x86 Generic System Framebuffers support") since the "efi-framebuffer"
and "simple-framebuffer" platform devices are registered at a later time.
Link: https://lore.kernel.org/r/20211110200253.rfudkt3edbd3nsyj@lahvuun/
Fixes: d391c5827107 ("drivers/firmware: move x86 Generic System Framebuffers support")
Reported-by: Ilya Trukhanov <[email protected]>
Cc: <[email protected]> # 5.15.x
Signed-off-by: Javier Martinez Canillas <[email protected]>
Reviewed-by: Daniel Vetter <[email protected]>
---
Changes in v3:
- Cc <[email protected]> since a Fixes: tag is not enough (gregkh).
Changes in v2:
- Add a Link: tag with a reference to the bug report (Thorsten Leemhuis).
- Add a comment explaining why the probe fails earlier (Daniel Vetter).
- Add a Fixes: tag for stable to pick the fix (Daniel Vetter).
- Add Daniel Vetter's Reviewed-by: tag.
- Improve the commit message and mention the culprit commit
drivers/video/fbdev/efifb.c | 11 +++++++++++
drivers/video/fbdev/simplefb.c | 11 +++++++++++
2 files changed, 22 insertions(+)
diff --git drivers/video/fbdev/efifb.c drivers/video/fbdev/efifb.c
index edca3703b964..ea42ba6445b2 100644
--- drivers/video/fbdev/efifb.c
+++ drivers/video/fbdev/efifb.c
@@ -351,6 +351,17 @@ static int efifb_probe(struct platform_device *dev)
char *option = NULL;
efi_memory_desc_t md;
+ /*
+ * Generic drivers must not be registered if a framebuffer exists.
+ * If a native driver was probed, the display hardware was already
+ * taken and attempting to use the system framebuffer is dangerous.
+ */
+ if (num_registered_fb > 0) {
+ dev_err(&dev->dev,
+ "efifb: a framebuffer is already registered\n");
+ return -EINVAL;
+ }
+
if (screen_info.orig_video_isVGA != VIDEO_TYPE_EFI || pci_dev_disabled)
return -ENODEV;
diff --git drivers/video/fbdev/simplefb.c drivers/video/fbdev/simplefb.c
index 62f0ded70681..b63074fd892e 100644
--- drivers/video/fbdev/simplefb.c
+++ drivers/video/fbdev/simplefb.c
@@ -407,6 +407,17 @@ static int simplefb_probe(struct platform_device *pdev)
struct simplefb_par *par;
struct resource *mem;
+ /*
+ * Generic drivers must not be registered if a framebuffer exists.
+ * If a native driver was probed, the display hardware was already
+ * taken and attempting to use the system framebuffer is dangerous.
+ */
+ if (num_registered_fb > 0) {
+ dev_err(&pdev->dev,
+ "simplefb: a framebuffer is already registered\n");
+ return -EINVAL;
+ }
+
if (fb_get_options("simplefb", NULL))
return -ENODEV;
--
2.33.1
On Thu, Nov 11, 2021 at 12:57:57PM +0100, Javier Martinez Canillas wrote:
> The efifb and simplefb drivers just render to a pre-allocated frame buffer
> and rely on the display hardware being initialized before the kernel boots.
>
> But if another driver already probed correctly and registered a fbdev, the
> generic drivers shouldn't be probed since an actual driver for the display
> hardware is already present.
>
> This is more likely to occur after commit d391c5827107 ("drivers/firmware:
> move x86 Generic System Framebuffers support") since the "efi-framebuffer"
> and "simple-framebuffer" platform devices are registered at a later time.
>
> Link: https://lore.kernel.org/r/20211110200253.rfudkt3edbd3nsyj@lahvuun/
> Fixes: d391c5827107 ("drivers/firmware: move x86 Generic System Framebuffers support")
> Reported-by: Ilya Trukhanov <[email protected]>
> Cc: <[email protected]> # 5.15.x
> Signed-off-by: Javier Martinez Canillas <[email protected]>
> Reviewed-by: Daniel Vetter <[email protected]>
> ---
>
> Changes in v3:
> - Cc <[email protected]> since a Fixes: tag is not enough (gregkh).
>
> Changes in v2:
> - Add a Link: tag with a reference to the bug report (Thorsten Leemhuis).
> - Add a comment explaining why the probe fails earlier (Daniel Vetter).
> - Add a Fixes: tag for stable to pick the fix (Daniel Vetter).
> - Add Daniel Vetter's Reviewed-by: tag.
> - Improve the commit message and mention the culprit commit
>
> drivers/video/fbdev/efifb.c | 11 +++++++++++
> drivers/video/fbdev/simplefb.c | 11 +++++++++++
> 2 files changed, 22 insertions(+)
>
> diff --git drivers/video/fbdev/efifb.c drivers/video/fbdev/efifb.c
> index edca3703b964..ea42ba6445b2 100644
> --- drivers/video/fbdev/efifb.c
> +++ drivers/video/fbdev/efifb.c
> @@ -351,6 +351,17 @@ static int efifb_probe(struct platform_device *dev)
> char *option = NULL;
> efi_memory_desc_t md;
>
> + /*
> + * Generic drivers must not be registered if a framebuffer exists.
> + * If a native driver was probed, the display hardware was already
> + * taken and attempting to use the system framebuffer is dangerous.
> + */
> + if (num_registered_fb > 0) {
> + dev_err(&dev->dev,
> + "efifb: a framebuffer is already registered\n");
> + return -EINVAL;
> + }
> +
> if (screen_info.orig_video_isVGA != VIDEO_TYPE_EFI || pci_dev_disabled)
> return -ENODEV;
>
> diff --git drivers/video/fbdev/simplefb.c drivers/video/fbdev/simplefb.c
> index 62f0ded70681..b63074fd892e 100644
> --- drivers/video/fbdev/simplefb.c
> +++ drivers/video/fbdev/simplefb.c
> @@ -407,6 +407,17 @@ static int simplefb_probe(struct platform_device *pdev)
> struct simplefb_par *par;
> struct resource *mem;
>
> + /*
> + * Generic drivers must not be registered if a framebuffer exists.
> + * If a native driver was probed, the display hardware was already
> + * taken and attempting to use the system framebuffer is dangerous.
> + */
> + if (num_registered_fb > 0) {
> + dev_err(&pdev->dev,
> + "simplefb: a framebuffer is already registered\n");
> + return -EINVAL;
> + }
> +
> if (fb_get_options("simplefb", NULL))
> return -ENODEV;
>
> --
> 2.33.1
>
This patch fixes the suspend issue I was experiencing. Thank you.
Tested-by: Ilya Trukhanov <[email protected]>