[Intel-gfx] [PATCH] drm/i915/display: Read planes watermarks during initial state readout

[Ville Syrjälä]

On Fri, Feb 19, 2021 at 08:16:25PM +0000, Souza, Jose wrote:
> On Fri, 2021-02-19 at 21:46 +0200, Ville Syrjälä wrote:
> > On Fri, Feb 19, 2021 at 11:16:23AM -0800, José Roberto de Souza wrote:
> > > Without this readout all plane watermarks will be kept at zero in the
> > > initial state readount causing two problems.
> > > 
> > > All active planes will always have their watermarks programmed
> > > again, even if what firmware programmed matches with the sanitized
> > > state during driver takeover.
> > > 
> > > State mismatch errors in disabled planes as watermarks will erroneous
> > > match with the calculated state if firmware left watermark registers
> > > with non-zero values.
> > > 
> > > Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/display/intel_display.c | 2 ++
> > >  1 file changed, 2 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> > > index d0da88751c72..14fba4411be7 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > > @@ -13620,6 +13620,8 @@ static void intel_modeset_readout_hw_state(struct drm_device *dev)
> > >  			drm_calc_timestamping_constants(&slave->base,
> > >  							&slave_crtc_state->hw.adjusted_mode);
> > >  		}
> > > +
> > > +		skl_pipe_wm_get_hw_state(crtc, &crtc_state->wm.skl.optimal);
> > 
> > Strange. skl_wm_get_hw_state() should be doing this already.
> 
> It is only doing some ddb readouts noting related to plane watermarks, maybe call skl_pipe_wm_get_hw_state() from there would be better?

The call is definitely there in my copy of the code:

skl_wm_get_hw_state(struct drm_i915_private *dev_priv)
{
 	struct intel_dbuf_state *dbuf_state =
                to_intel_dbuf_state(dev_priv->dbuf.obj.state);
        struct intel_crtc *crtc;

        for_each_intel_crtc(&dev_priv->drm, crtc) {
                struct intel_crtc_state *crtc_state =
                        to_intel_crtc_state(crtc->base.state);
                enum pipe pipe = crtc->pipe;
                enum plane_id plane_id;

                skl_pipe_wm_get_hw_state(crtc, &crtc_state->wm.skl.optimal);
		...


-- 
Ville Syrjälä
Intel