Re: [PATCH] drm/i915/skl: disable display side power well support for now

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

On Thu, Nov 05, 2015 at 11:04:11PM +0200, Imre Deak wrote:
> The display power well support on this platform is in a somewhat broken
> state atm, so disable it by default.
> 
> This in effect will get rid of incorrect assert WARNs about the CSR/DMC
> firmware not being loaded during power well toggling. It also removes a
> problem during driver loading where a register is accessed while its
> backing power well is down, resulting in another WARN. Until we come up
> with the root cause of the second problem and the proper fix for both
> issues, keep all display side power wells on.
> 
> Also clarify a bit the option description.
> 
> Reported-by: Dave Airlie <airlied@redhat.com>
> Signed-off-by: Imre Deak <imre.deak@intel.com>

Looks all right.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> ---
>  drivers/gpu/drm/i915/i915_params.c      |  5 +++--
>  drivers/gpu/drm/i915/intel_runtime_pm.c | 20 ++++++++++++++++++++
>  2 files changed, 23 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
> index ca9b8f6..e950135 100644
> --- a/drivers/gpu/drm/i915/i915_params.c
> +++ b/drivers/gpu/drm/i915/i915_params.c
> @@ -38,7 +38,7 @@ struct i915_params i915 __read_mostly = {
>  	.enable_ppgtt = -1,
>  	.enable_psr = 0,
>  	.preliminary_hw_support = IS_ENABLED(CONFIG_DRM_I915_PRELIMINARY_HW_SUPPORT),
> -	.disable_power_well = 1,
> +	.disable_power_well = -1,
>  	.enable_ips = 1,
>  	.prefault_disable = 0,
>  	.load_detect_test = 0,
> @@ -127,7 +127,8 @@ MODULE_PARM_DESC(preliminary_hw_support,
>  
>  module_param_named_unsafe(disable_power_well, i915.disable_power_well, int, 0600);
>  MODULE_PARM_DESC(disable_power_well,
> -	"Disable the power well when possible (default: true)");
> +	"Disable display power wells when possible"
> +	"(-1=auto [default], 0=power wells always on, 1=power wells disabled when possible)");
>  
>  module_param_named_unsafe(enable_ips, i915.enable_ips, int, 0600);
>  MODULE_PARM_DESC(enable_ips, "Enable IPS (default: true)");
> diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
> index ec010ee..14016f0 100644
> --- a/drivers/gpu/drm/i915/intel_runtime_pm.c
> +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
> @@ -1811,6 +1811,23 @@ static struct i915_power_well bxt_power_wells[] = {
>  	}
>  };
>  
> +static int
> +sanitize_disable_power_well_option(const struct drm_i915_private *dev_priv,
> +				   int disable_power_well)
> +{
> +	if (disable_power_well >= 0)
> +		return !!disable_power_well;
> +
> +	if (IS_SKYLAKE(dev_priv)) {
> +		DRM_DEBUG_KMS("Disabling display power well support\n");
> +		return 0;
> +	}
> +
> +	return 1;
> +
> +
> +}
> +
>  #define set_power_wells(power_domains, __power_wells) ({		\
>  	(power_domains)->power_wells = (__power_wells);			\
>  	(power_domains)->power_well_count = ARRAY_SIZE(__power_wells);	\
> @@ -1827,6 +1844,9 @@ int intel_power_domains_init(struct drm_i915_private *dev_priv)
>  {
>  	struct i915_power_domains *power_domains = &dev_priv->power_domains;
>  
> +	i915.disable_power_well = sanitize_disable_power_well_option(dev_priv,
> +						     i915.disable_power_well);
> +
>  	mutex_init(&power_domains->lock);
>  
>  	/*
> -- 
> 2.5.0
> 
> _______________________________________________
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-- 
Ville Syrjälä
Intel OTC
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