Re: [PATCH RFC 2/5] drm/i915: Only update required power domains.

[Ander Conselvan De Oliveira <conselvan2@gmail.com>]

On Wed, 2015-04-22 at 13:24 +0200, maarten.lankhorst@linux.intel.com
wrote:
> From: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> 
> This prevents unnecessarily updating power domains, while still
> enabling all power domains on initial setup.
> 
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 52 ++++++++++++++++++++++++++++--------
>  1 file changed, 41 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 92d54dd30d7e..438d8e213748 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -5163,36 +5163,72 @@ static unsigned long get_crtc_power_domains(struct drm_crtc *crtc)
>  	return mask;
>  }
>  
> +static bool
> +needs_modeset(struct drm_crtc_state *state)
> +{
> +	return state->mode_changed || state->active_changed;
> +}
> +
>  static void modeset_update_crtc_power_domains(struct drm_atomic_state *state)
>  {
>  	struct drm_device *dev = state->dev;
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	unsigned long pipe_domains[I915_MAX_PIPES] = { 0, };
>  	struct intel_crtc *crtc;
> +	bool init_power = dev_priv->power_domains.init_power_on;
> +	bool any_power = init_power, any_modeset = false;
> +	unsigned long domains;
>  
>  	/*
>  	 * First get all needed power domains, then put all unneeded, to avoid
>  	 * any unnecessary toggling of the power wells.
>  	 */
>  	for_each_intel_crtc(dev, crtc) {
> +		int idx = drm_crtc_index(&crtc->base);
> +		struct drm_crtc_state *crtc_state = state->crtc_states[idx];
>  		enum intel_display_power_domain domain;
>  
> -		if (!crtc->base.state->enable)
> +		if (!init_power && !crtc_state)
> +			continue;
> +
> +		if (needs_modeset(crtc->base.state))
> +			any_modeset = true;
> +
> +		if (crtc->base.state->enable)
> +			pipe_domains[crtc->pipe] =
> +				get_crtc_power_domains(&crtc->base);
> +
> +		if (pipe_domains[crtc->pipe] == crtc->enabled_power_domains)
>  			continue;
>  
> -		pipe_domains[crtc->pipe] = get_crtc_power_domains(&crtc->base);
> +		WARN_ON(!init_power && !needs_modeset(crtc->base.state));
> +
> +		any_power = true;
> +		domains = pipe_domains[crtc->pipe] &
> +			  ~crtc->enabled_power_domains;
>  
> -		for_each_power_domain(domain, pipe_domains[crtc->pipe])
> +		for_each_power_domain(domain, domains)
>  			intel_display_power_get(dev_priv, domain);

Isn't intel_display_power_get() already a no-op if the power domain is
already active, except for the reference counting? Or did I miss
something?

Ander


>  	}
>  
> -	if (dev_priv->display.modeset_global_resources)
> +	if (any_modeset && dev_priv->display.modeset_global_resources)
>  		dev_priv->display.modeset_global_resources(state);
>  
> +	if (!any_power)
> +		return;
> +
>  	for_each_intel_crtc(dev, crtc) {
> +		int idx = drm_crtc_index(&crtc->base);
> +		struct drm_crtc_state *crtc_state = state->crtc_states[idx];
>  		enum intel_display_power_domain domain;
>  
> -		for_each_power_domain(domain, crtc->enabled_power_domains)
> +		if (!init_power && !crtc_state)
> +			continue;
> +
> +		domains = crtc->enabled_power_domains &
> +			  ~pipe_domains[crtc->pipe];
> +
> +		for_each_power_domain(domain, domains)
>  			intel_display_power_put(dev_priv, domain);
>  
>  		crtc->enabled_power_domains = pipe_domains[crtc->pipe];
> @@ -11144,12 +11180,6 @@ static bool intel_crtc_in_use(struct drm_crtc *crtc)
>  	return false;
>  }
>  
> -static bool
> -needs_modeset(struct drm_crtc_state *state)
> -{
> -	return state->mode_changed || state->active_changed;
> -}
> -
>  static void
>  intel_modeset_update_state(struct drm_atomic_state *state)
>  {


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