[Intel-gfx] [DMC_BUGFIX_SKL_V2 4/5] drm/i915/skl: Do not disable cdclk PLL if csr firmware is present

[Sunil Kamath]

On Wednesday 26 August 2015 01:36 AM, Animesh Manna wrote:
> While display engine entering into low power state no need to disable
> cdclk pll as CSR firmware of dmc will take care. If pll is already
> enabled firmware execution sequence will be blocked. This is one
> of the criteria for dmc to work properly.
>
> v1: Initial version.
>
> v2: Based on review comment from Daniel added code commnent.
>
> Cc: Daniel Vetter <daniel.vetter at intel.com>
> Cc: Damien Lespiau <damien.lespiau at intel.com>
> Cc: Imre Deak <imre.deak at intel.com>
> Cc: Sunil Kamath <sunil.kamath at intel.com>
> Signed-off-by: Animesh Manna <animesh.manna at intel.com>
> Signed-off-bt: Vathsala Nagaraju <vathsala.nagaraju at intel.com>
> Signed-off-by: Rajneesh Bhardwaj <rajneesh.bhardwaj at intel.com>
> ---
>   drivers/gpu/drm/i915/intel_display.c | 14 ++++++++++----
>   1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index f604ce1..b6bef20 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -5687,10 +5687,16 @@ void skl_uninit_cdclk(struct drm_i915_private *dev_priv)
>   	if (I915_READ(DBUF_CTL) & DBUF_POWER_STATE)
>   		DRM_ERROR("DBuf power disable timeout\n");
>   
> -	/* disable DPLL0 */
> -	I915_WRITE(LCPLL1_CTL, I915_READ(LCPLL1_CTL) & ~LCPLL_PLL_ENABLE);
> -	if (wait_for(!(I915_READ(LCPLL1_CTL) & LCPLL_PLL_LOCK), 1))
> -		DRM_ERROR("Couldn't disable DPLL0\n");
> +	/*
> +	 * DMC assumes ownership of LCPLL and will get confused if we touch it.
> +	 */
> +	if (dev_priv->csr.dmc_payload) {
> +		/* disable DPLL0 */
> +		I915_WRITE(LCPLL1_CTL, I915_READ(LCPLL1_CTL) &
> +					~LCPLL_PLL_ENABLE);
> +		if (wait_for(!(I915_READ(LCPLL1_CTL) & LCPLL_PLL_LOCK), 1))
> +			DRM_ERROR("Couldn't disable DPLL0\n");
> +	}
>   
>   	intel_display_power_put(dev_priv, POWER_DOMAIN_PLLS);
>   }

Valid fix and patch is ready for merge now.

Reviewed-by: A.Sunil Kamath <sunil.kamath at intel.com> 
<mailto:sunil.kamath at intel.com>

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