Hi Javier, On Thu, Sep 12, 2024 at 06:33:58PM +0200, Javier Martinez Canillas wrote: > That's a very good point. I'm actually not familiar with Coreboot and I > used an educated guess (in the case of DT for example, that's the main > source of truth and I didn't know if a Core table was in a similar vein). > > Maybe something like the following (untested) patch then? Julius is more familiar with the Coreboot + payload ecosystem than me, but his explanations make sense to me, as does this patch. > From de1c32017006f4671d91b695f4d6b4e99c073ab2 Mon Sep 17 00:00:00 2001 > From: Javier Martinez Canillas <javierm@xxxxxxxxxx> > Date: Thu, 12 Sep 2024 18:31:55 +0200 > Subject: [PATCH] firmware: coreboot: Don't register a pdev if screen_info data > is available > > 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 this information to > the Linux kernel. > > If that the case, early arch x86 boot code will fill the global struct > screen_info data and that data used by the Generic System Framebuffers > (sysfb) framework to add a platform device with platform data about the > system framebuffer. Normally, these sorts of "early" and "later" ordering descriptions would set alarm bells when talking about independent drivers. But I suppose the "early arch" code has better ordering guaranteeds than drivers, so this should be fine. > But later then the framebuffer_coreboot driver will try to do the same > framebuffer (using the information from the Coreboot table), which will > lead to an error due a simple-framebuffer.0 device already 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 the 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@xxxxxxxxxxxx> > Link: https://lore.kernel.org/all/ZuCG-DggNThuF4pj@b20ea791c01f/T/#ma7fb65acbc1a56042258adac910992bb225a20d2 > Suggested-by: Julius Werner <jwerner@xxxxxxxxxxxx> > Signed-off-by: Javier Martinez Canillas <javierm@xxxxxxxxxx> > --- > drivers/firmware/google/framebuffer-coreboot.c | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/drivers/firmware/google/framebuffer-coreboot.c b/drivers/firmware/google/framebuffer-coreboot.c > index daadd71d8ddd..4e50da17cd7e 100644 > --- a/drivers/firmware/google/framebuffer-coreboot.c > +++ b/drivers/firmware/google/framebuffer-coreboot.c > @@ -15,6 +15,7 @@ > #include <linux/module.h> > #include <linux/platform_data/simplefb.h> > #include <linux/platform_device.h> > +#include <linux/screen_info.h> > > #include "coreboot_table.h" > > @@ -27,6 +28,7 @@ static int framebuffer_probe(struct coreboot_device *dev) > int i; > u32 length; > struct lb_framebuffer *fb = &dev->framebuffer; > + struct screen_info *si = &screen_info; > struct platform_device *pdev; > struct resource res; > struct simplefb_platform_data pdata = { > @@ -36,6 +38,20 @@ static int framebuffer_probe(struct coreboot_device *dev) > .format = NULL, > }; > > + /* > + * If the global screen_info data has been filled, the Generic > + * System Framebuffers (sysfb) will already register a platform Did you mean 'platform_device'? > + * and pass the screen_info as platform_data to a driver that > + * could scan-out using the system provided framebuffer. > + * > + * On Coreboot systems, the advertise LB_TAG_FRAMEBUFFER entry s/advertise/advertised/ ? > + * in the Coreboot table should only be used if the payload did > + * not set video mode info and passed it to the Linux kernel. s/passed/pass/ > + */ > + if (si->orig_video_isVGA == VIDEO_TYPE_VLFB || > + si->orig_video_isVGA == VIDEO_TYPE_EFI) This line is using spaces for indentation. It should use a tab, and then spaces for alignment. But presumably this will change based on Thomas's suggestions anyway. > + return -EINVAL; Is EINVAL right? IIUC, that will print a noisier error to the logs. I believe the "expected" sorts of return codes are ENODEV or ENXIO. (See call_driver_probe().) ENODEV seems like a fine choice, similar to several of the other return codes already used here. Anyway, this seems along the right track. Thanks for tackling, and feel free to carry a: Reviewed-by: Brian Norris <briannorris@xxxxxxxxxxxx> > + > if (!fb->physical_address) > return -ENODEV; > > -- > Best regards, > > Javier Martinez Canillas > Core Platforms > Red Hat >
