Re: [PATCH 02/10] drm/i915: disable power well support on platforms without runtime PM support

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Dec 15, 2015 at 08:10:30PM +0200, Imre Deak wrote:
> All platforms with power well support have runtime PM support, so
> simplify things by explicitly disabling power well support on platforms
> without runtime PM support. This results in holding the init power domain
> reference whenever the driver is loaded in addition to an RPM reference,
> which reflects the reality better and makes it possible to simplify
> things by removing the HAS_RUNTIME_PM special casing from more places in
> a follow-up patch.
> 
> Signed-off-by: Imre Deak <imre.deak@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_runtime_pm.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
> index 9945040..f4ff5f5 100644
> --- a/drivers/gpu/drm/i915/intel_runtime_pm.c
> +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
> @@ -1908,6 +1908,11 @@ static int
>  sanitize_disable_power_well_option(const struct drm_i915_private *dev_priv,
>  				   int disable_power_well)
>  {
> +	if (!HAS_RUNTIME_PM(dev_priv)) {
> +		DRM_DEBUG_KMS("No runtime PM support, disabling display power well support\n");
> +		return 0;
> +	}

Feels a bit too magic to me. Needs a comment at least, otherwise someone
is going to change disable_power_well back into something you can disable
at runtime and then all the old stuff might break.

Grabbing an extra rpm reference explicitly for this purpose might be
less confusing.

> +
>  	if (disable_power_well >= 0)
>  		return !!disable_power_well;
>  
> -- 
> 2.5.0

-- 
Ville Syrjälä
Intel OTC
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