Re: [PATCH 4/4] drm/i915/display: Add handling for new "active bpc" property

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

On Tue, Jun 08, 2021 at 07:19:31PM +0200, Werner Sembach wrote:
> 
> Am 07.06.21 um 22:33 schrieb Werner Sembach:
> > Am 07.06.21 um 08:47 schrieb Werner Sembach:
> >>
> >> Am 04.06.21 um 19:30 schrieb Ville Syrjälä:
> >>> On Fri, Jun 04, 2021 at 07:17:23PM +0200, Werner Sembach wrote:
> >>>> This commits implements the "active bpc" drm property for the Intel 
> >>>> GPU driver.
> >>>>
> >>>> Signed-off-by: Werner Sembach <wse@tuxedocomputers.com>
> >>>> ---
> >>>>   drivers/gpu/drm/i915/display/intel_display.c | 13 +++++++++++++
> >>>>   drivers/gpu/drm/i915/display/intel_dp.c      |  8 ++++++--
> >>>>   drivers/gpu/drm/i915/display/intel_dp_mst.c  |  4 +++-
> >>>>   drivers/gpu/drm/i915/display/intel_hdmi.c    |  4 +++-
> >>>>   4 files changed, 25 insertions(+), 4 deletions(-)
> >>>>
> >>>> diff --git a/drivers/gpu/drm/i915/display/intel_display.c 
> >>>> b/drivers/gpu/drm/i915/display/intel_display.c
> >>>> index 64e9107d70f7..f7898d9d7438 100644
> >>>> --- a/drivers/gpu/drm/i915/display/intel_display.c
> >>>> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> >>>> @@ -10164,6 +10164,8 @@ static void intel_atomic_commit_tail(struct 
> >>>> intel_atomic_state *state)
> >>>>       struct drm_i915_private *dev_priv = to_i915(dev);
> >>>>       struct intel_crtc_state *new_crtc_state, *old_crtc_state;
> >>>>       struct intel_crtc *crtc;
> >>>> +    struct drm_connector *connector;
> >>>> +    struct drm_connector_state *new_conn_state;
> >>>>       u64 put_domains[I915_MAX_PIPES] = {};
> >>>>       intel_wakeref_t wakeref = 0;
> >>>>       int i;
> >>>> @@ -10324,6 +10326,17 @@ static void 
> >>>> intel_atomic_commit_tail(struct intel_atomic_state *state)
> >>>>       }
> >>>>       intel_runtime_pm_put(&dev_priv->runtime_pm, state->wakeref);
> >>>>   +    /* Extract information from crtc to communicate it to 
> >>>> userspace as connector properties */
> >>>> +    for_each_new_connector_in_state(&state->base, connector, 
> >>>> new_conn_state, i) {
> >>>> +        struct drm_crtc *crtc = new_conn_state->crtc;
> >>>> +        if (crtc) {
> >>>> +            new_crtc_state = 
> >>>> to_intel_crtc_state(drm_atomic_get_new_crtc_state(&state->base, 
> >>>> crtc));
> >>> intel_atomic_get_new_crtc_state()
> >> Thanks, will use that.
> >>>
> >>>> + new_conn_state->active_bpc = new_crtc_state->pipe_bpp / 3;
> >>>> +        }
> >>>> +        else
> >>>> +            new_conn_state->active_bpc = 0;
> >>>> +    }
> >>> This also seems too late. I think the whole thing should be
> >>> done somewhere around the normal swap_state() stuff.
> >> Ok, will look into it.
> > So I tried to put it in intel_atomic_commit() after 
> > drm_atomic_helper_swap_state() and before 
> > INIT_WORK(&state->base.commit_work, intel_atomic_commit_work) (which 
> > creates a worker for intel_atomic_commit_tail), but somewhere in 
> > between, the connector_state seems to change: The bpc written with the 
> > for_each_new_connector_in_state() loop, gets discarded.
> 
> This was not the problem. Setting the drm property immutable made it 
> (also?) immutable from the driver context, which I didn't test separately.
> 
> Removed the immutable again and moved the loop.

Immutable props are special. See __drm_object_property_get_value().

-- 
Ville Syrjälä
Intel