On Wed, May 06, 2020 at 10:06:15AM +0200, Thomas Zimmermann wrote: > Hi > > Am 04.05.20 um 17:31 schrieb Daniel Vetter: > > On Mon, May 04, 2020 at 02:07:22PM +0200, Thomas Zimmermann wrote: > >> Hi Emil > >> > >> Am 01.05.20 um 15:20 schrieb Emil Velikov: > >>> Hi Thomas, > >>> > >>> Couple of fly-by ideas/suggestions. > >>> > >>> On Thu, 30 Apr 2020 at 10:13, Thomas Zimmermann <tzimmermann@xxxxxxx> wrote: > >>>> > >>>> Suspending failed because there's no mode if the CRTC is being > >>>> disabled. Early-out in this case. This fixes runtime PM for ast. > >>>> > >>>> Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx> > >>>> --- > >>>> drivers/gpu/drm/ast/ast_mode.c | 3 +++ > >>>> 1 file changed, 3 insertions(+) > >>>> > >>>> diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c > >>>> index 7a9f20a2fd303..089b7d9a0cf3f 100644 > >>>> --- a/drivers/gpu/drm/ast/ast_mode.c > >>>> +++ b/drivers/gpu/drm/ast/ast_mode.c > >>>> @@ -801,6 +801,9 @@ static int ast_crtc_helper_atomic_check(struct drm_crtc *crtc, > >>>> return -EINVAL; > >>> Unrelated: > >>> This feels quite dirty. If AST1180 does not support atomic modeset > >>> simply remove the DRIVER_ATOMIC bit. > >>> You can do that at runtime, via drm_device::driver_features in say, > >>> ast_detect_chip()? > >> > >> The line you commented on dates back to non-atomic modesetting, but I > >> don't know what the story behind AST1180 is. It is explicitly disabled > >> in the list of PCI IDs, but the driver has plenty of code for it. It > >> looks as if the chip can only do pageflipping with a pre-set video mode. > >> > >> As it is right now, the AST1180 code could probably be deleted entirely. > >> > >>> > >>> The drm_driver::driver_features is immutable, or it ought to be. > >>> > >>>> } > >>>> > >>>> + if (!state->enable) > >>>> + return 0; /* no checks required if CRTC is being disabled */ > >>>> + > >>> I cannot think of a reason why a driver would need to perform > >>> crtc_atomic_check, if the crtc is being disabled. > >>> Can you spot any? If not, this should be better served in core, which > >>> calls this callback. > >>> Correct? > >> Ast is a bit of a special case, because it tests the incoming mode > >> against a list of re-defined modes. With the crtc being disabled, the > >> incoming mode is 0 in all fields. Obviously that's not a valid mode, and > >> we need that additional test here. > >> > >> In the general case, I'd see 'crtc check' as part of the larger atomic > >> infrastructure. I can imagine that configurations require the CRTC to be > >> enabled before other HW blocks work. So a driver might have a reason to > >> run crtc's check even for disabled crtcs (at least to verify that the > >> crtc is not disabled). I don't think this can be handled in the core easily. > > > > Jumping out of ->atomic_check callbacks when stuff is all off is fairly > > standard pattern. So much standard that I'm kinda wondering whether we > > shouldn't just make it the default in atomic helpers - so many drivers > > forget to do it and break in funny ways. > > If there comes a driver that really must handle the 'disable case' in > its check handler, such a change would be hard to revert. Removing the > check from the DRM core could regress drivers that depend on the new > semantics. Yeah I know, that's why I don't want to push this into helpers (it wouldn't ever be in core code). But it surely is tempting, because we have tons of bugs in this area. I've made a patch series a while ago that only cleaned up some of the minor confusion between plane_state->crtc and plane_state->fb (they're only set together or neither). Losing choice either way :-/ -Daniel > > Best regards > Thomas > > > -Daniel > > > >> > >> Best regards > >> Thomas > >> > >>> > >>> HTH > >>> -Emil > >>> _______________________________________________ > >>> dri-devel mailing list > >>> dri-devel@xxxxxxxxxxxxxxxxxxxxx > >>> https://lists.freedesktop.org/mailman/listinfo/dri-devel > >>> > >> > >> -- > >> Thomas Zimmermann > >> Graphics Driver Developer > >> SUSE Software Solutions Germany GmbH > >> Maxfeldstr. 5, 90409 Nürnberg, Germany > >> (HRB 36809, AG Nürnberg) > >> Geschäftsführer: Felix Imendörffer > >> > > > > > > > > > >> _______________________________________________ > >> dri-devel mailing list > >> dri-devel@xxxxxxxxxxxxxxxxxxxxx > >> https://lists.freedesktop.org/mailman/listinfo/dri-devel > > > > > > -- > Thomas Zimmermann > Graphics Driver Developer > SUSE Software Solutions Germany GmbH > Maxfeldstr. 5, 90409 Nürnberg, Germany > (HRB 36809, AG Nürnberg) > Geschäftsführer: Felix Imendörffer > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
