Den 16.12.2021 09.20, skrev Thomas Zimmermann: > Hi > > Am 15.12.21 um 22:37 schrieb Noralf Trønnes: >> >> >> Den 15.12.2021 01.59, skrev Javier Martinez Canillas: >>> According to disable Documentation/admin-guide/kernel-parameters.txt, >>> this >>> parameter can be used to disable kernel modesetting. >>> >>> DRM drivers will not perform display-mode changes or accelerated >>> rendering >>> and only the systewm system framebuffer will be available if it was >>> set-up. >>> >>> But only a few DRM drivers currently check for nomodeset, make this >>> driver >>> to also support the command line parameter. >>> >>> Signed-off-by: Javier Martinez Canillas <javierm@xxxxxxxxxx> >>> --- >>> >> >> I don't understand why this is applicable to USB drivers, there's no way >> the firmware can setup a framebuffer and continue pushing pixels over >> USB when Linux has been given control over the USB bus? >> >> The same argument goes for the SPI drivers in drm/tiny/ as well. > > The intended semantics of the option is to disable every display output > except for the buffer provided by the firmware. > If that's the case this patch is: Acked-by: Noralf Trønnes <noralf@xxxxxxxxxxx> > With USB it still would still disable the driver. That's useful if only > for debugging. There are also systems with hard-wired USB displays where > one cannot just unplug the adapter. > > Admittedly, USB graphics is a bit of an odd use case, but neither is it > too far fetched IMHO. > > Best regards > Thomas > >> >> Noralf. >> >>> drivers/gpu/drm/gud/gud_drv.c | 3 +++ >>> 1 file changed, 3 insertions(+) >>> >>> diff --git a/drivers/gpu/drm/gud/gud_drv.c >>> b/drivers/gpu/drm/gud/gud_drv.c >>> index 3f9d4b9a1e3d..4d253d249512 100644 >>> --- a/drivers/gpu/drm/gud/gud_drv.c >>> +++ b/drivers/gpu/drm/gud/gud_drv.c >>> @@ -446,6 +446,9 @@ static int gud_probe(struct usb_interface *intf, >>> const struct usb_device_id *id) >>> u32 *formats; >>> int ret, i; >>> + if (drm_firmware_drivers_only()) >>> + return -ENODEV; >>> + >>> ret = usb_find_bulk_out_endpoint(intf->cur_altsetting, &bulk_out); >>> if (ret) >>> return ret; >>> >
