[Intel-gfx] [PATCH 2/2] drm/i915/skl: Increase PCODE CDCLK change notify timeout

[Chris Wilson]

On Thu, Nov 24, 2016 at 05:32:59PM +0200, Imre Deak wrote:
> commit 848496e5902833600f7992f4faa82dc1546051ba
> Author: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Date:   Wed Jul 13 16:32:03 2016 +0300
> 
>     drm/i915: Wait up to 3ms for the pcu to ack the cdclk change request on SKL
> 
> increased the timeout to match the spec, but we still see a timeout on
> at least one SKL. A CDCLK change request following the failed one will
> succeed nevertheless, so let's try to increase the timeout to 10ms.
> 
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Reference: https://bugs.freedesktop.org/show_bug.cgi?id=97929
> Signed-off-by: Imre Deak <imre.deak at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 5d11002..3b711f4 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -6261,7 +6261,7 @@ static bool skl_cdclk_pcu_ready(struct drm_i915_private *dev_priv)
>  
>  static bool skl_cdclk_wait_for_pcu_ready(struct drm_i915_private *dev_priv)
>  {
> -	return _wait_for(skl_cdclk_pcu_ready(dev_priv), 3000, 10) == 0;
> +	return _wait_for(skl_cdclk_pcu_ready(dev_priv), 10000, 10) == 0;
>  }

I can't think of a better approach to kick the pcu. But that is a wakeup
every 10us for 10ms.

{
	int ret;

	ret = wait_for_us(skl_cdclk_pcu_ready(dev_priv), 10);
	if (ret)
		ret = wait_for(skl_cdclk_pcu_ready(dev_priv), 10);

	return ret;
}

would spin for the first 10us then do a more gentle probe for the next
10ms.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre