Imre Deak <imre.d...@intel.com> writes:

> [ text/plain ]
> When determining whether CDCLK is enabled by BIOS and so we should skip
> reprogramming it, we didn't check the related DBUF power request and
> state. In theory BIOS could enable one without the other so check for
> this case and reprogram things if something is amiss.
>
> Signed-off-by: Imre Deak <imre.d...@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 28 ++++++++++++++++++++++++++--
>  1 file changed, 26 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c 
> b/drivers/gpu/drm/i915/intel_display.c
> index 1fbe619..447d46e 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -5440,14 +5440,38 @@ static void broxton_set_cdclk(struct drm_i915_private 
> *dev_priv, int frequency)
>       intel_update_cdclk(dev_priv->dev);
>  }
>  
> +static bool broxton_cdclk_is_enabled(struct drm_i915_private *dev_priv)
> +{
> +     if (!(I915_READ(BXT_DE_PLL_ENABLE) & BXT_DE_PLL_PLL_ENABLE))
> +             return false;
> +
> +     /* TODO: Check for a valid CDCLK rate */
> +

Discussed about the pll lock in irc with Imre. I think pll lock bit
should be included in the sanity inspection here too.

But that can be follow ups.

Reviewed-by: Mika Kuoppala <mika.kuopp...@intel.com>


> +     if (!(I915_READ(DBUF_CTL) & DBUF_POWER_REQUEST)) {
> +             DRM_DEBUG_DRIVER("CDCLK enabled, but DBUF power not 
> requested\n");
> +
> +             return false;
> +     }
> +
> +     if (!(I915_READ(DBUF_CTL) & DBUF_POWER_STATE)) {
> +             DRM_DEBUG_DRIVER("CDCLK enabled, but DBUF power hasn't 
> settled\n");
> +
> +             return false;
> +     }
> +
> +     return true;
> +}
> +
>  void broxton_init_cdclk(struct drm_i915_private *dev_priv)
>  {
>       /* check if cd clock is enabled */
> -     if (I915_READ(BXT_DE_PLL_ENABLE) & BXT_DE_PLL_PLL_ENABLE) {
> -             DRM_DEBUG_KMS("Display already initialized\n");
> +     if (broxton_cdclk_is_enabled(dev_priv)) {
> +             DRM_DEBUG_KMS("CDCLK already enabled, won't reprogram it\n");
>               return;
>       }
>  
> +     DRM_DEBUG_KMS("CDCLK not enabled, enabling it\n");
> +
>       /*
>        * FIXME:
>        * - The initial CDCLK needs to be read from VBT.
> -- 
> 2.5.0
>
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