Re: [PATCH 07/11] drm/i915: Warn if there's a cdclk change in progess

[Jesse Barnes <jbarnes@virtuousgeek.org>]

On Fri, 13 Jun 2014 13:37:53 +0300
ville.syrjala@linux.intel.com wrote:

> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> If someone is interested in the current cdclk frquency it should
> be stable and not in process of changing frquency. Warn if the current
> and requested cdclk don't match in .get_display_clock_spee() on vlv.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 29dddec..601e97e 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -5234,6 +5234,10 @@ static int valleyview_get_display_clock_speed(struct drm_device *dev)
>  
>  	divider = val & DISPLAY_FREQUENCY_VALUES;
>  
> +	WARN((val & DISPLAY_FREQUENCY_STATUS) !=
> +	     (divider << DISPLAY_FREQUENCY_STATUS_SHIFT),
> +	     "cdclk change in progress\n");
> +
>  	return DIV_ROUND_CLOSEST(vco << 1, divider + 1);
>  }
>  

Hm, there's not much we can do in this case, so rather than warn maybe
we should try a wait instead, and only warn if it times out?  Even then
there's not much we can do aside from poking the PUnit folks.

-- 
Jesse Barnes, Intel Open Source Technology Center
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