[Intel-gfx] [PATCH v3 1/1] drm/i915/xe2lpd: implement WA for underruns while enabling FBC

[Kahola, Mika]

> -----Original Message-----
> From: Intel-gfx <intel-gfx-bounces at lists.freedesktop.org> On Behalf Of Vinod Govindapillai
> Sent: Thursday, November 9, 2023 12:25 AM
> To: intel-gfx at lists.freedesktop.org
> Cc: Syrjala, Ville <ville.syrjala at intel.com>
> Subject: [Intel-gfx] [PATCH v3 1/1] drm/i915/xe2lpd: implement WA for underruns while enabling FBC
> 
> FIFO underruns are observed when FBC is enabled on plane 2 or 3.
> This is root caused to a HW bug and the recommended WA is to update the FBC enabling sequence. The plane binding register bits
> need to be updated separately before programming the FBC enable bit.
> 
> HSD: 16021232047
> Signed-off-by: Vinod Govindapillai <vinod.govindapillai at intel.com>

To me the patch seems to do what WA suggests.

Reviewed-by: Mika Kahola <mika.kahola at intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_fbc.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c
> index bde12fe62275..8a3594e4d992 100644
> --- a/drivers/gpu/drm/i915/display/intel_fbc.c
> +++ b/drivers/gpu/drm/i915/display/intel_fbc.c
> @@ -608,6 +608,7 @@ static u32 ivb_dpfc_ctl(struct intel_fbc *fbc)  static void ivb_fbc_activate(struct intel_fbc *fbc)  {
>  	struct drm_i915_private *i915 = fbc->i915;
> +	u32 dpfc_ctl;
> 
>  	if (DISPLAY_VER(i915) >= 10)
>  		glk_fbc_program_cfb_stride(fbc);
> @@ -617,8 +618,18 @@ static void ivb_fbc_activate(struct intel_fbc *fbc)
>  	if (intel_gt_support_legacy_fencing(to_gt(i915)))
>  		snb_fbc_program_fence(fbc);
> 
> +	/*
> +	 * xe2lpd: WA for FIFO underruns while enabling FBC on planes 2 or 3
> +	 * 1.Write FBC_CTL with Plane binding set correctly with FBC enable = 0
> +	 * 2.Write FBC_CTL with Plane binding set correctly with FBC enable = 1
> +	 * HSD: 16021232047
> +	 */
> +	dpfc_ctl = ivb_dpfc_ctl(fbc);
> +	if (DISPLAY_VER(i915) >= 20)
> +		intel_de_write(i915, ILK_DPFC_CONTROL(fbc->id), dpfc_ctl);
> +
>  	intel_de_write(i915, ILK_DPFC_CONTROL(fbc->id),
> -		       DPFC_CTL_EN | ivb_dpfc_ctl(fbc));
> +		       DPFC_CTL_EN | dpfc_ctl);
>  }
> 
>  static bool ivb_fbc_is_compressing(struct intel_fbc *fbc)
> --
> 2.34.1