Hi Javier Am 12.11.23 um 11:35 schrieb Javier Martinez Canillas:
Andrew Worsley <amworsley@xxxxxxxxx> writes: Hello Andrew,On Sat, 11 Nov 2023 at 20:10, Javier Martinez Canillas <javierm@xxxxxxxxxx> wrote:....On Sat, 11 Nov 2023 at 15:30, Andrew Worsley <amworsley@xxxxxxxxx> wrote:The simpledrm.c does not call aperture_remove_conflicting_devices() in it's probe function as the drivers/video/aperture.c documentation says it should. Consequently it's request for the FB memory fails.The current behaviour is correct since aperture_remove_conflicting_devices() is for native drivers to remove simple framebuffer devices such as simpledrm, simplefb, efifb, etc.The efifb is the driver that has "grabbed" the FB earlier Here's a debug output with a dump_stack() call in the devm_aperture_acquire() % grep --color -A14 -B4 devm_aperture_acquire ~/dmesg2.txt [ 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 [ 0.055771] devm_aperture_acquire: dump stack for debugging [ 0.055775] CPU: 2 PID: 1 Comm: swapper/0 Tainted: G SI see. This is the problem then. Your platform then is using a Device Tree that contains a "simple-framebuffer" node but also doing a UEFI boot and providing an EFI GOP table that is picked by the Linux EFI stub on boot. [...]... [ 3.085302] simple-framebuffer bd58dc000.framebuffer: [drm] *ERROR* could not acquire memory range [??? 0xffff6e1d8629d580-0x2a5000001a7 flags 0x0]: -16 [ 3.086433] simple-framebuffer: probe of bd58dc000.framebuffer failed with error -16 ...This is -EBUSY. What is your kernel configuration? Can you share it please.Attached - hope that's acceptable...Thanks a lot for providing this. It was very helpful to understand the issue. [...]I would rather try to understand what is going on in your setup and why the acquire is returning -EBUSY.Ok - thanks - let me know where to go from here.I think that what we should do instead is to prevent both the EFI GOP and "simple-framebuffer" to provide a system framebuffer information and the kernel to register two devices (a "simple-framebuffer" by the OF core and an "efi-framebuffer" by the sysfb infrastructure). In my opinion, the DTB is the best source of truth on an DT platform and so is the sysfb that should be disabled if there's a "simple-framebuffer" DT node found. Can you please try the following (untested) patch? From 7bf4a7917962c24c9f15aaf6e798db9d652c6806 Mon Sep 17 00:00:00 2001 From: Javier Martinez Canillas <javierm@xxxxxxxxxx> Date: Sun, 12 Nov 2023 11:06:22 +0100 Subject: [PATCH] of/platform: Disable sysfb if a simple-framebuffer node is found 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. Reported-by: Andrew Worsley <amworsley@xxxxxxxxx> Signed-off-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
Reviewed-by: Thomas Zimmermann <tzimmermann@xxxxxxx>It's a known problem and a know workaround. I don't find it particularly elegant, but have no other solution either. It would be much nicer to have a way for the sysfb code to detect whether it should create a device for the framebuffer.
Best regards Thomas
--- drivers/of/platform.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/drivers/of/platform.c b/drivers/of/platform.c index f235ab55b91e..a9fd91e6a6df 100644 --- a/drivers/of/platform.c +++ b/drivers/of/platform.c @@ -621,8 +621,21 @@ 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 table 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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