[Intel-gfx] [PATCH] drm/i915/psr: Add continuous full frame bit together with single

[Souza, Jose]

On Tue, 2022-11-29 at 09:51 +0200, Jouni Högander wrote:
> Currently we are observing occasionally display flickering or complete
> freeze. This is narrowed down to be caused by single full frame update
> (SFF).
> 
> SFF bit after it's written gets cleared by HW in subsequent vblank
> i.e. when the update is sent to the panel. SFF bit is required to be
> written together with partial frame update (PFU) bit. After the SFF
> bit gets cleared by the HW psr2 man trk ctl register still contains
> PFU bit. If there is subsequent update for any reason we will end up
> having selective update/fetch configuration where start line is 0 and
> end line is 0.
> 

How did you get this information(start and end line 0)?

>  Also selective fetch configuration for the planes is
> not properly performed. This seems to be causing problems with some
> panels.
> 
> Using CFF without SFF doesn't work either because it may happen that
> psr2 man track ctl register is overwritten by next update before
> vblank triggers sending the update. This is causing problems to
> psr_invalidate/flush. Using CFF and SFF together solves the problems
> as SFF is cleared only by HW in subsequent vblank.

This looks dangerous, have you checked with HW engineers if setting both could cause any issue?
At the SFF write you could get what is the current vblank counter and properly handle future PSR2_MAN_TRK_CTL writes.

> 
> Fix the flickering/freeze issue by adding continuous full frame with
> single full frame update and switch to partial frame update only when
> selective update area is properly calculated and configured.
> 
> This is also workaround for HSD 14014971508

Please use versions in your patches, you had 2 patches in the previous approach with the same subject but no versioning and no information about what
changed between versions.

> 
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: José Roberto de Souza <jose.souza at intel.com>
> Cc: Mika Kahola <mika.kahola at intel.com>
> 
> Reported-by: Lee Shawn C <shawn.c.lee at intel.com>
> Signed-off-by: Jouni Högander <jouni.hogander at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_psr.c | 19 ++++++++++---------
>  1 file changed, 10 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
> index 5b678916e6db..88388201684e 100644
> --- a/drivers/gpu/drm/i915/display/intel_psr.c
> +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> @@ -1510,7 +1510,8 @@ static void psr_force_hw_tracking_exit(struct intel_dp *intel_dp)
>  			       PSR2_MAN_TRK_CTL(intel_dp->psr.transcoder),
>  			       man_trk_ctl_enable_bit_get(dev_priv) |
>  			       man_trk_ctl_partial_frame_bit_get(dev_priv) |
> -			       man_trk_ctl_single_full_frame_bit_get(dev_priv));
> +			       man_trk_ctl_single_full_frame_bit_get(dev_priv) |
> +			       man_trk_ctl_continuos_full_frame(dev_priv));
>  
>  	/*
>  	 * Display WA #0884: skl+
> @@ -1624,11 +1625,8 @@ static void psr2_man_trk_ctl_calc(struct intel_crtc_state *crtc_state,
>  	val |= man_trk_ctl_partial_frame_bit_get(dev_priv);
>  
>  	if (full_update) {
> -		/*
> -		 * Not applying Wa_14014971508:adlp as we do not support the
> -		 * feature that requires this workaround.
> -		 */
>  		val |= man_trk_ctl_single_full_frame_bit_get(dev_priv);
> +		val |= man_trk_ctl_continuos_full_frame(dev_priv);
>  		goto exit;
>  	}
>  
> @@ -2307,12 +2305,15 @@ static void _psr_flush_handle(struct intel_dp *intel_dp)
>  			/* can we turn CFF off? */
>  			if (intel_dp->psr.busy_frontbuffer_bits == 0) {
>  				u32 val = man_trk_ctl_enable_bit_get(dev_priv) |
> -					  man_trk_ctl_partial_frame_bit_get(dev_priv) |
> -					  man_trk_ctl_single_full_frame_bit_get(dev_priv);
> +					man_trk_ctl_partial_frame_bit_get(dev_priv) |
> +					man_trk_ctl_single_full_frame_bit_get(dev_priv) |
> +					man_trk_ctl_continuos_full_frame(dev_priv);

style.

>  
>  				/*
> -				 * turn continuous full frame off and do a single
> -				 * full frame
> +				 * turn continuous full frame off and do a single full frame. Still
> +				 * keep cff bit enabled as we don't have proper SU configuration in
> +				 * case update is sent for any reason after sff bit gets cleared by
> +				 * the HW on next vblank.


turn off and keep bit enabled?! makes no sense this comment.

>  				 */
>  				intel_de_write(dev_priv, PSR2_MAN_TRK_CTL(intel_dp->psr.transcoder),
>  					       val);