On Mon, 13 Nov 2023 at 23:57, Javier Martinez Canillas <javierm@xxxxxxxxxx> wrote: > > Andrew Worsley <amworsley@xxxxxxxxx> writes: > > Hello Andrew, > > > On Mon, 13 Nov 2023 at 20:18, Thomas Zimmermann <tzimmermann@xxxxxxx> wrote: > >> 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. > >> > > > [...] > > > > > I applied the patch and just the simpledrm driver is probed (the efifb is not): > > >[...] > > Great, thanks for testing. The patch works then as expected. Can I get > your Tested-by then ? Sure absolutely. > > > [...] > We were talking with Thomas that the sysfb design seems to be reaching its > limits and need some rework but currently you either need some driver that > matches the "simple-framebuffer" device that is registered by OF or won't > get an early framebuffer in the system. > > That could be either simpledrm or simplefb. But if a DT has a device node > for "simple-framebuffer", how can the OF core know if there is a driver to > match that device? And same for any other device defined in the DTB. > > It's similar on platforms that use sysfb to register the device (e.g: x86) > since either "simple-framebuffer" is registered (if CONFIG_SYSFB_SIMPLEFB > is enabled) or "efi-framebuffer" (if CONFIG_SYSFB_SIMPLEFB is disabled). > > That means CONFIG_SYSFB_SIMPLEFB=y and CONFIG_DRM_SIMPLEDRM disabled won't > work either, even if CONFIG_FB_EFI=y which is the case you are mentioning. > > What I think that doesn't make sense is to remove conflicting framebuffers > from drivers that can only handle firmware provided framebuffers. As said > in the other thread, drm_aperture_remove_framebuffers() is only meant for > native DRM drivers. Ok - I'm taking it that conflicts between EFI and DT didn't happen in the past but when they do DT wins. I guess there may be more such conflicts in the future so would be resolved in a similar way as more drivers are updated to support DT settings. Perhaps one day all drivers would have DT settings and this could be standardised in some way. > -- > Best regards, > > Javier Martinez Canillas > Core Platforms > Red Hat > Thanks Andrew
