[Intel-gfx] [PATCH v2 6/9] drm/i915/display/adlp: Optimize PSR2 power-savings in corner cases

[Souza, Jose]

On Thu, 2021-09-30 at 10:35 +0300, Gwan-gyeong Mun wrote:
> 
> On 9/30/21 3:14 AM, José Roberto de Souza wrote:
> > The Wa_14014971508 is required to fix scanout when a feature that i915
> > do not support is enabled and this feature is not planned to be enabled
> > for adlp.
> > 
> > Keeping this workaround enabled can badly hurt power-savings when
> > a full frame fetch is required(see psr2_sel_fetch_plane_state_supported()
> > and psr2_sel_fetch_pipe_state_supported()).
> > 
> > Here a example that could badly hurt power-savings, userspace does
> > a page flip to a rotated plane, so CONTINUOS_FULL_FRAME set.
> > But then for a whole 30 seconds nothing in the screen requires updates
> > but because CONTINUOS_FULL_FRAME is set, it will not go into DC5/DC6.
> > 
> > Reverting Wa_14014971508 fixes that, as only a single frame will be
> > sent and then display can go to DC5/DC6 for those 30 seconds of
> > idleness.
> > 
> And add a little more explanation here.
> DC6v is a power saving state where the display engine is powered off 
> when display enters PSR2 in the video playback.
> And the Wa_14014971508 related to DC6v.

Will do thanks.

> 
> Reviewed-by: Gwan-gyeong Mun <gwan-gyeong.mun at intel.com>
> 
> > BSpec: 54369
> > Cc: Gwan-gyeong Mun <gwan-gyeong.mun at intel.com>
> > Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
> > ---
> >   drivers/gpu/drm/i915/display/intel_psr.c | 11 +++--------
> >   1 file changed, 3 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
> > index e8af39591dfea..b37f123fe0c97 100644
> > --- a/drivers/gpu/drm/i915/display/intel_psr.c
> > +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> > @@ -1499,15 +1499,10 @@ static void psr2_man_trk_ctl_calc(struct intel_crtc_state *crtc_state,
> >   
> >   	if (full_update) {
> >   		/*
> > -		 * Wa_14014971508:adlp
> > -		 * SINGLE_FULL_FRAME bit is not hold in register so can not be
> > -		 * restored by DMC, so using CONTINUOS_FULL_FRAME to mimic that
> > +		 * Not applying Wa_14014971508:adlp as we do not support the
> > +		 * feature that requires this workaround.
> >   		 */
> > -		if (IS_ALDERLAKE_P(dev_priv))
> > -			val |= ADLP_PSR2_MAN_TRK_CTL_SF_CONTINUOS_FULL_FRAME;
> > -		else
> > -			val |= PSR2_MAN_TRK_CTL_SF_SINGLE_FULL_FRAME;
> > -
> > +		val |= man_trk_ctl_single_full_frame_bit_get(dev_priv);
> >   		goto exit;
> >   	}
> >   
> >