[Intel-gfx] [PATCH 10/10] drm/i915: Zero unused WM1 watermarks on VLV/CHV

[Clint Taylor]

On 06/24/2015 12:00 PM, ville.syrjala at linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> The hardware supposedly ignores the WM1 watermarks while the PND
> deadline mode is enabled, but clear out the register just in case.
> This is what the other OS does, and it does make register dumps look
> more consistent when we don't have partial WM1 values lingering in
> the registers (some WM1 watermarks already get zeroed when the actually
> used DSPFW registers get written).
>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>   drivers/gpu/drm/i915/intel_pm.c | 6 ++++++
>   1 file changed, 6 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index c8e7ef3..dc8a9c9 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -927,6 +927,12 @@ static void vlv_write_wm_values(struct intel_crtc *crtc,
>   			   FW_WM(wm->pipe[PIPE_A].primary >> 8, PLANEA_HI));
>   	}
>
> +	/* zero (unused) WM1 watermarks */
> +	I915_WRITE(DSPFW4, 0);
> +	I915_WRITE(DSPFW5, 0);
> +	I915_WRITE(DSPFW6, 0);
> +	I915_WRITE(DSPHOWM1, 0);
> +
>   	POSTING_READ(DSPFW1);
>   }
>
>

Reviewed-by: Clint Taylor <Clinton.A.Taylor at intel.com>
Tested-by: Clint Taylor <Clinton.A.Taylor at intel.com>