Re: [PATCH 12/16] drm/i915/bxt: Sanitize the DBUF HW state together with CDCLK

[Mika Kuoppala <mika.kuoppala@linux.intel.com>]

Imre Deak <imre.deak@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.deak@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.kuoppala@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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