Re: [PATCH 2/2] drm/i915: calculate pfit changes in set_config v3

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

On 11/11/2014 10:30 PM, Jesse Barnes wrote:
> This should allow us to avoid mode sets for some panel fitter config
> changes.
> 
> v2:
>    - fixup pfit comment (Ander)
> v3:
>    - fixup pfit disable shortcut, only apply to gen4 for now (Jesse)

I see that the patch does what it claims it does, so you can use the 
following r-b tag. However, I want to point out that all the 
documentation I came across, including for PCH platforms, state that 
the proper modeset order is to enable pfit before the pipe is enabled 
and to disable it after disabling the pipe. So I assume you know better 
than the docs.

Reviewed-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>

> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
> ---
>   drivers/gpu/drm/i915/intel_display.c | 73 ++++++++++++++++++++++++++++++------
>   1 file changed, 62 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 58ed4ef..e7175b1 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -2861,17 +2861,8 @@ static void intel_update_pipe_size(struct intel_crtc *crtc)
>   		return;
>   
>   	/*
> -	 * Update pipe size and adjust fitter if needed: the reason for this is
> -	 * that in compute_mode_changes we check the native mode (not the pfit
> -	 * mode) to see if we can flip rather than do a full mode set. In the
> -	 * fastboot case, we'll flip, but if we don't update the pipesrc and
> -	 * pfit state, we'll end up with a big fb scanned out into the wrong
> -	 * sized surface.
> -	 *
> -	 * To fix this properly, we need to hoist the checks up into
> -	 * compute_mode_changes (or above), check the actual pfit state and
> -	 * whether the platform allows pfit disable with pipe active, and only
> -	 * then update the pipesrc and pfit state, even on the flip path.
> +	 * See intel_pfit_changed for info on when we're allowed to
> +	 * do this w/o a pipe shutdown.
>   	 */
>   
>   	adjusted_mode = &crtc->config.adjusted_mode;
> @@ -11266,6 +11257,62 @@ static void disable_crtc_nofb(struct intel_crtc *crtc)
>   	crtc->new_config = NULL;
>   }
>   
> +/* Do we need a mode set due to pfit changes? */
> +static bool intel_pfit_changed(struct drm_device *dev,
> +			       struct intel_crtc_config *new_config,
> +			       struct intel_crtc_config *cur_config)
> +{
> +	bool ret = false;
> +
> +	if (HAS_DDI(dev) || HAS_PCH_SPLIT(dev)) {
> +		/*
> +		 * On PCH platforms we can disable pfit w/o a pipe shutdown,
> +		 * otherwise we'll need a mode set.
> +		 */
> +		if (new_config->pch_pfit.enabled &&
> +		    cur_config->pch_pfit.enabled)
> +			ret = false;
> +		else if (new_config->pch_pfit.enabled &&
> +			 !cur_config->pch_pfit.enabled)
> +			ret = true;
> +		else if (!new_config->pch_pfit.enabled &&
> +			 cur_config->pch_pfit.enabled)
> +			ret = false;
> +		else if (!new_config->pch_pfit.enabled &&
> +			 !cur_config->pch_pfit.enabled)
> +			ret = false;
> +	} else if (IS_GEN4(dev)) {
> +		/*
> +		 * We may be able to get away with this on more chips, but
> +		 * we need more testing here.
> +		 */
> +		bool new_enabled, old_enabled;
> +
> +		new_enabled = !!(new_config->gmch_pfit.control & PFIT_ENABLE);
> +		old_enabled = !!(cur_config->gmch_pfit.control & PFIT_ENABLE);
> +
> +		/* 9xx only needs a shutdown to disable pfit */
> +		if (new_enabled && old_enabled)
> +			ret = false;
> +		else if (new_enabled && !old_enabled)
> +			ret = false;
> +		else if (!new_enabled && old_enabled)
> +			ret = true;
> +		else if (!new_enabled && !old_enabled)
> +			ret = false;
> +	} else {
> +		bool new_enabled, old_enabled;
> +
> +		new_enabled = !!(new_config->gmch_pfit.control & PFIT_ENABLE);
> +		old_enabled = !!(cur_config->gmch_pfit.control & PFIT_ENABLE);
> +
> +		if (new_enabled != old_enabled)
> +			ret = true;
> +	}
> +
> +	return ret;
> +}
> +
>   static int intel_crtc_set_config(struct drm_mode_set *set)
>   {
>   	struct drm_device *dev;
> @@ -11334,6 +11381,10 @@ static int intel_crtc_set_config(struct drm_mode_set *set)
>   		if (to_intel_crtc(set->crtc)->new_config->has_infoframe ||
>   		    to_intel_crtc(set->crtc)->config.has_infoframe)
>   			config->mode_changed = true;
> +
> +		if (intel_pfit_changed(dev, to_intel_crtc(set->crtc)->new_config,
> +				       &to_intel_crtc(set->crtc)->config))
> +			config->mode_changed = true;
>   	}
>   
>   	/* set_mode will free it in the mode_changed case */
> 

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