[Intel-gfx] [PATCH 1/2] drm/i915/dp: Do not set master_trans bit in bitmak if INVALID_TRANSCODER

[Manasi Navare]

On Thu, Jan 23, 2020 at 08:31:55PM +0200, Ville Syrjälä wrote:
> On Thu, Jan 23, 2020 at 06:25:29PM +0000, Souza, Jose wrote:
> > On Wed, 2020-01-22 at 16:24 -0800, Manasi Navare wrote:
> > > In the port sync mode, for the master crtc, the master_transcoder is
> > > INVALID.
> > > In that case since its value is -1, do not set the bit in the
> > > bitmask.
> > > 
> > > Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > Fixes: d0eed1545fe7 ("drm/i915: Fix post-fastset modeset check for
> > > port sync")
> > > Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/display/intel_display.c | 6 ++++--
> > >  1 file changed, 4 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/display/intel_display.c
> > > b/drivers/gpu/drm/i915/display/intel_display.c
> > > index 878d331b9e8c..79f9054078ea 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > > @@ -14649,8 +14649,10 @@ static int intel_atomic_check(struct
> > > drm_device *dev,
> > >  		}
> > >  
> > >  		if (is_trans_port_sync_mode(new_crtc_state)) {
> > > -			u8 trans = new_crtc_state-
> > > >sync_mode_slaves_mask |
> > > -				   BIT(new_crtc_state-
> > > >master_transcoder);
> > > +			u8 trans = new_crtc_state-
> > > >sync_mode_slaves_mask;
> > > +
> > > +			if (new_crtc_state->master_transcoder !=
> > > INVALID_TRANSCODER)
> > > +				trans |= BIT(new_crtc_state-
> > > >master_transcoder);
> > 
> > Why not set master_transcoder in port sync master too? Would avoid have
> > this check here and in future other places.
> 
> Not how the hardware works. So would complicate hw readout and
> programming code needlessly.

Yes and thats how we identify that it is the master since its master trans is INVALID

Manasi

> 
> > 
> > >  
> > >  			if (intel_cpu_transcoders_need_modeset(state,
> > > trans)) {
> > >  				new_crtc_state->uapi.mode_changed =
> > > true;
> 
> -- 
> Ville Syrjälä
> Intel