Re: [PATCH 21/21] drm/i915: Set BXT cdclk to minimum initially

[Imre Deak <imre.deak@intel.com>]

On Fri, 2016-05-13 at 23:41 +0300, ville.syrjala@linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> In case the driver is initialized without active displays, we should
> just drop the cdclk to the minimum frequency right off the bat. There
> might not be a modeset to drop it to the minimum late rafter all.
> 
> With DMC supposedly we should always have the cdclk up and running.
> The DMC will shut the DE PLL down when appropriate, so let's nuke
> the related FIXMEs as well. Trying to do anything different would
> go against the expectations of the DMC firmware, and we all know
> how fragile the DMC firmware is.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Reviewed-by: Imre Deak <imre.deak@intel.com>

> ---
>  drivers/gpu/drm/i915/intel_display.c | 9 ++-------
>  1 file changed, 2 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 9725ba59716e..ac8d448e96d1 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -118,6 +118,7 @@ static void ironlake_pfit_enable(struct intel_crtc *crtc);
>  static void intel_modeset_setup_hw_state(struct drm_device *dev);
>  static void intel_pre_disable_primary_noatomic(struct drm_crtc *crtc);
>  static int ilk_max_pixel_rate(struct drm_atomic_state *state);
> +static int broxton_calc_cdclk(int max_pixclk);
>  
>  struct intel_limit {
>  	struct {
> @@ -5501,10 +5502,8 @@ void broxton_init_cdclk(struct drm_i915_private *dev_priv)
>  	 * FIXME:
>  	 * - The initial CDCLK needs to be read from VBT.
>  	 *   Need to make this change after VBT has changes for BXT.
> -	 * - check if setting the max (or any) cdclk freq is really necessary
> -	 *   here, it belongs to modeset time
>  	 */
> -	broxton_set_cdclk(dev_priv, 624000);
> +	broxton_set_cdclk(dev_priv, broxton_calc_cdclk(0));
>  }
>  
>  void broxton_uninit_cdclk(struct drm_i915_private *dev_priv)
> @@ -5944,10 +5943,6 @@ static int valleyview_calc_cdclk(struct drm_i915_private *dev_priv,
>  
>  static int broxton_calc_cdclk(int max_pixclk)
>  {
> -	/*
> -	 * FIXME:
> -	 * - set 19.2MHz bypass frequency if there are no active pipes
> -	 */
>  	if (max_pixclk > 576000)
>  		return 624000;
>  	else if (max_pixclk > 384000)
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