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firmware: coreboot: Don't register a pdev if screen_info data is present

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On coreboot platforms, a system framebuffer may be provided to the Linux
kernel by filling a LB_TAG_FRAMEBUFFER entry in the coreboot table. But
a coreboot payload (e.g: SeaBIOS) could also provide its own framebuffer
information to the Linux kernel.

If that's the case, arch x86 boot code will fill the global screen_info
data and this used by the Generic System Framebuffers (sysfb) framework,
to register a platform device with pdata about the system's framebuffer.

But later, the framebuffer_coreboot driver will try to do the same and
attempt to register a "simple-framebuffer" platform device (using the
information from the coreboot table), which will lead to an error due a
device with the same name already being registered:

    sysfs: cannot create duplicate filename '/bus/platform/devices/simple-framebuffer.0'
    ...
    coreboot: could not register framebuffer
    framebuffer coreboot8: probe with driver framebuffer failed with error -17

To prevent this issue, make the framebuffer_core driver to not register
a platform device if the global struct screen_info data has been filled.

Reported-by: Brian Norris <briannorris@chromium.org>
Closes: https://lore.kernel.org/all/ZuCG-DggNThuF4pj@b20ea791c01f/T/#ma7fb65acbc1a56042258adac910992bb225a20d2
Suggested-by: Julius Werner <jwerner@chromium.org>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Link: https://lore.kernel.org/r/20240916110040.1688511-3-javierm@redhat.com
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
This commit is contained in:
Javier Martinez Canillas
2024-09-16 13:00:26 +02:00
committed by Tzung-Bi Shih
parent 6074e90502
commit 67f488dff1
1 changed files with 14 additions and 0 deletions
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14
drivers/firmware/google/framebuffer-coreboot.c
View File

@@ -15,6 +15,7 @@
#include <linux/module.h>
#include <linux/platform_data/simplefb.h>
#include <linux/platform_device.h>
#include <linux/sysfb.h>
#include "coreboot_table.h"
@@ -36,6 +37,19 @@ static int framebuffer_probe(struct coreboot_device *dev)
.format = NULL,
};
/*
* On coreboot systems, the advertised LB_TAG_FRAMEBUFFER entry
* in the coreboot table should only be used if the payload did
* not pass a framebuffer information to the Linux kernel.
*
* If the global screen_info data has been filled, the Generic
* System Framebuffers (sysfb) will already register a platform
* device and pass that screen_info as platform_data to a driver
* that can scan-out using the system provided framebuffer.
*/
if (sysfb_handles_screen_info())
return -ENODEV;
if (!fb->physical_address)
return -ENODEV;