On Mon, Aug 03, 2015 at 09:55:34PM +0530, 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.
> 
> Cc: Daniel Vetter <[email protected]>
> Cc: Damien Lespiau <[email protected]>
> Cc: Imre Deak <[email protected]>
> Cc: Sunil Kamath <[email protected]>
> Signed-off-by: Animesh Manna <[email protected]>
> Signed-off-bt: Vathsala Nagaraju <[email protected]>
> Signed-off-by: Rajneesh Bhardwaj <[email protected]>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c 
> b/drivers/gpu/drm/i915/intel_display.c
> index af0bcfe..ef2ef4d 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -5675,10 +5675,13 @@ 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");
> +     if (dev_priv->csr.dmc_payload) {
> +             /* disable DPLL0 */

Imo this needs a proper comment (and the current one is useless since it
just states exactly what the code does and is redundant). What about

        /* DMC assumes ownership of LCPLL and will get confused if we
         * touch it. */

instead before the if?
-Daniel

> +             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);
>  }
> -- 
> 2.0.2
> 
> _______________________________________________
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> [email protected]
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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