Re: [Intel-gfx] [PATCH] drm/atomic: Add the crtc to affected crtc only if uapi.enable = true

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Mar 25, 2021 at 03:01:29PM -0700, Navare, Manasi wrote:
> On Fri, Mar 19, 2021 at 11:27:59PM +0200, Ville Syrjälä wrote:
> > On Fri, Mar 19, 2021 at 02:26:24PM -0700, Navare, Manasi wrote:
> > > On Fri, Mar 19, 2021 at 11:12:41PM +0200, Ville Syrjälä wrote:
> > > > On Fri, Mar 19, 2021 at 01:54:13PM -0700, Navare, Manasi wrote:
> > > > > On Fri, Mar 19, 2021 at 04:56:24PM +0200, Ville Syrjälä wrote:
> > > > > > On Thu, Mar 18, 2021 at 04:01:26PM -0700, Navare, Manasi wrote:
> > > > > > > So basically we see this warning only in case of bigjoiner when
> > > > > > > drm_atomic_check gets called without setting the state->allow_modeset flag.
> > > > > > 
> > > > > > Considering the code is 'WARN(!state->allow_modeset, ...' that
> > > > > > fact should be rather obvious.
> > > > > > 
> > > > > > > 
> > > > > > > So do you think that in i915, in intel_atomic_check_bigjoiner() we should only
> > > > > > > steal the crtc when allow_modeset flag is set in state?
> > > > > > 
> > > > > > No. If you fully read drm_atomic_check_only() you will observe
> > > > > > that it will reject any commit w/ allow_modeset==false which 
> > > > > > needs a modeset. And it does that before the WARN.
> > > > > > 
> > > > > > So you're barking up the wrong tree here. The problem I think
> > > > > > is that you're just computing requested_crtcs wrong.
> > > > > 
> > > > > So here in this case, requested CRTC = 0x1 since it requests modeset on CRTC 0
> > > > > Now in teh atomic check, it steals the slave CRTC 1 and hence affected CRTC comes out
> > > > > as 0x3 and hence the mismatch.
> > > > 
> > > > Hmm. How can it be 0x3 if we filtered out the uapi.enable==false case?
> > > > 
> > > 
> > > Yes if I add that condition like in this patch then it correctly calculates
> > > the affected crtc bitmask as only 0x1 since it doesnt include the slave crtc.
> > > So with this patch, requested crtc = 0x 1, affected crtc = 0x1
> > > 
> > > If this looks good then this fixes our bigjoiner warnings.
> > > Does this patch look good to you as is then?
> > 
> > I think you still need to fix the requested_crtcs calculation.
> 
> We calculate requested crtc at the beginning :
> for_each_new_crtc_in_state(state, crtc, new_crtc_state, i)
>                 requested_crtc |= drm_crtc_mask(crtc);
> 
> Are you suggesting adding this to after:
>  if (config->funcs->atomic_check) {
>                 ret = config->funcs->atomic_check(state->dev, state);
> 
>                 if (ret) {
>                         DRM_DEBUG_ATOMIC("atomic driver check for %p failed: %d\n",
>                                          state, ret);
>                         return ret;
>                 }
> 		requested_crtc |= drm_crtc_mask(crtc);    // Here it will have requested crtc = 0x11
>         }
> 
> in this case here the state should already have master crtc 0 and slave crtc 1
> and that requested crtc should already be 0x11
> 
> Then in that case we dont need any special check for calculating affected crtc, that also will be 0x11

All I'm saying is that you're currently calculating requested_crtcs and
affected_crtcs differently. So I'm not at all surprised that they might
not match.

-- 
Ville Syrjälä
Intel
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