Am 13.11.23 um 09:51 schrieb Javier Martinez Canillas:
Some DT platforms use EFI to boot and in this case the EFI Boot Services
may register a EFI_GRAPHICS_OUTPUT_PROTOCOL handle, that will later be
queried by the Linux EFI stub to fill the global struct screen_info data.
The data is used by the Generic System Framebuffers (sysfb) framework to
add a platform device with platform data about the system framebuffer.
But if there is a "simple-framebuffer" node in the DT, the OF core will
also do the same and add another device for the system framebuffer.
This could lead for example, to two platform devices ("simple-framebuffer"
and "efi-framebuffer") to be added and matched with their corresponding
drivers. So both efifb and simpledrm will be probed, leading to following:
[ 0.055752] efifb: framebuffer at 0xbd58dc000, using 16000k, total 16000k
[ 0.055755] efifb: mode is 2560x1600x32, linelength=10240, pages=1
[ 0.055758] efifb: scrolling: redraw
[ 0.055759] efifb: Truecolor: size=2:10:10:10, shift=30:20:10:0
...
[ 3.295896] simple-framebuffer bd58dc000.framebuffer: [drm] *ERROR*
could not acquire memory range [??? 0xffff79f30a29ee40-0x2a5000001a7
flags 0x0]: -16
[ 3.298018] simple-framebuffer: probe of bd58dc000.framebuffer
failed with error -16
To prevent the issue, make the OF core to disable sysfb if there is a node
with a "simple-framebuffer" compatible. That way only this device will be
registered and sysfb would not attempt to register another one using the
screen_info data even if this has been filled.
This seems the correct thing to do in this case because:
a) On a DT platform, the DTB is the single source of truth since is what
describes the hardware topology. Even if EFI Boot Services are used to
boot the machine.
b) The of_platform_default_populate_init() function is called in the
arch_initcall_sync() initcall level while the sysfb_init() function
is called later in the subsys_initcall() initcall level.
Reported-by: Andrew Worsley <amworsley@xxxxxxxxx>
Closes: https://lore.kernel.org/all/20231111042926.52990-2-amworsley@xxxxxxxxx
Signed-off-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
Reviewed-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
--- drivers/of/platform.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/drivers/of/platform.c b/drivers/of/platform.c index f235ab55b91e..0a692fdfef59 100644 --- a/drivers/of/platform.c +++ b/drivers/of/platform.c @@ -20,6 +20,7 @@ #include <linux/of_irq.h> #include <linux/of_platform.h> #include <linux/platform_device.h> +#include <linux/sysfb.h>#include "of_private.h" @@ -621,8 +622,21 @@ static int __init of_platform_default_populate_init(void)}node = of_get_compatible_child(of_chosen, "simple-framebuffer");- of_platform_device_create(node, NULL, NULL); - of_node_put(node); + if (node) { + /* + * Since a "simple-framebuffer" device is already added + * here, disable the Generic System Framebuffers (sysfb) + * to prevent it from registering another device for the + * system framebuffer later (e.g: using the screen_info + * data that may had been filled as well). + * + * This can happen for example on DT systems that do EFI + * booting and may provide a GOP handle to the EFI stub. + */ + sysfb_disable(); + of_platform_device_create(node, NULL, NULL); + of_node_put(node); + }/* Populate everything else. */of_platform_default_populate(NULL, NULL, NULL);
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Frankenstrasse 146, 90461 Nuernberg, Germany GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman HRB 36809 (AG Nuernberg)
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