| Message ID | 20211215010008.2545520-12-javierm@redhat.com (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
| Series | drm: Make all drivers to honour the nomodeset parameter | expand |
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@redhat.com> > --- > 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. 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; >
Hello Noralf, On 12/15/21 22:37, Noralf Trønnes wrote: > > > 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@redhat.com> >> --- >> > > 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. > That's a very good point. I included these mostly for consistency but if it's OK for the KMS drivers to just ignore the "nomodeset" parameter, I could drop all that are not for devices in the PCI or platform buses. Best regards,
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@redhat.com> >> --- >> > > 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. 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; >>
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@redhat.com> >>> --- >>> >> >> 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@tronnes.org> > 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; >>> >
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;
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@redhat.com> --- drivers/gpu/drm/gud/gud_drv.c | 3 +++ 1 file changed, 3 insertions(+)