[PATCH v2 1/2] drm/i915/fbc: keep FBC disabled if selective update is on in xe2lpd

[B, Jeevan]

> -----Original Message-----
> From: Govindapillai, Vinod <vinod.govindapillai at intel.com>
> Sent: Friday, March 21, 2025 3:15 PM
> To: intel-gfx at lists.freedesktop.org; intel-xe at lists.freedesktop.org
> Cc: Govindapillai, Vinod <vinod.govindapillai at intel.com>; Hogander, Jouni
> <jouni.hogander at intel.com>; Syrjala, Ville <ville.syrjala at intel.com>; Shankar,
> Uma <uma.shankar at intel.com>; Saarinen, Jani <jani.saarinen at intel.com>; B,
> Jeevan <jeevan.b at intel.com>
> Subject: [PATCH v2 1/2] drm/i915/fbc: keep FBC disabled if selective update is
> on in xe2lpd
> 
> FBC was disabled in case PSR2 selective update in display 12 to
> 14 as part of a wa. From xe2lpd onwards there is a logic to be implemented to
> decide between FBC and selective update. Until that logic is implemented keep
> FBC disabled in case selective update is enabled.
> 
> v1: updated patch description and some explanation and todo
> 
> Signed-off-by: Vinod Govindapillai <vinod.govindapillai at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_fbc.c | 14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c
> b/drivers/gpu/drm/i915/display/intel_fbc.c
> index b6978135e8ad..92b00da4c0ab 100644
> --- a/drivers/gpu/drm/i915/display/intel_fbc.c
> +++ b/drivers/gpu/drm/i915/display/intel_fbc.c
> @@ -1464,13 +1464,15 @@ static int intel_fbc_check_plane(struct
> intel_atomic_state *state,
>  	 * Recommendation is to keep this combination disabled
>  	 * Bspec: 50422 HSD: 14010260002
>  	 *
> -	 * In Xe3, PSR2 selective fetch and FBC dirty rect feature cannot
> -	 * coexist. So if PSR2 selective fetch is supported then mark that
> -	 * FBC is not supported.
> -	 * TODO: Need a logic to decide between PSR2 and FBC Dirty rect
> +	 * TODO: Implement a logic to select between PSR2 selective fetch and
> +	 * FBC based on Bspec: 68881 in xe2lpd onwards.
> +	 *
> +	 * As we still see some strange underruns in those platforms while
> +	 * disabling PSR2, keep FBC disabled in case of selective update is on
> +	 * until the selection logic is implemented.
>  	 */
Please add FIXME tag in comment and with this Patch LGTM. 

Reviewed-by: Jeevan B <jeevan.b at intel.com>
> -	if ((IS_DISPLAY_VER(display, 12, 14) ||
> HAS_FBC_DIRTY_RECT(display)) &&
> -	    crtc_state->has_sel_update && !crtc_state->has_panel_replay) {
> +	if (DISPLAY_VER(display) >= 12 && crtc_state->has_sel_update &&
> +	    !crtc_state->has_panel_replay) {
>  		plane_state->no_fbc_reason = "PSR2 enabled";
>  		return 0;
>  	}
> --
> 2.43.0