Re: [PATCH 10/20] drm/i915: Add atomic function to setup scalers scalers for a crtc.

[Matt Roper <matthew.d.roper@intel.com>]

On Wed, Apr 01, 2015 at 07:59:39PM -0700, Chandra Konduru wrote:
> intel_atomic_setup_scalers sets up scalers based on staged scaling
> requests coming from a crtc and its planes. This function should be
> called from crtc level check path.
> 
> If staged requests are supportable, function assigns scalers to
> requested planes and crtc. This function also takes into account
> the current planes using scalers but not being part of this
> atomic state for optimal operation of scalers. Note that the scaler
> assignement itself is staged into crtc_state and respective
> plane_states for later commit after all checks have been done.
> 
> overall high level flow:
>  - scaler requests are staged into crtc_state by planes/crtc
>  - check whether staged scaling requests can be supported
>  - add planes using scalers that aren't in current transaction
>  - assign scalers to requested users
>  - as part of plane commit, scalers will be committed
>    (i.e., either attached or detached) to respective planes in hw
>  - as part of crtc_commit, scaler will be either attached or detached
>    to crtc in hw
> 
> v2:
> -removed a log message (me)
> -changed input parameter to crtc_state (me)
> 
> v3:
> -remove assigning plane_state returned by drm_atomic_get_plane_state (Matt)
> -fail if there is an error from drm_atomic_get_plane_state (Matt)
> 
> Signed-off-by: Chandra Konduru <chandra.konduru@intel.com>

So looking ahead through the patch series, it looks like the places you
call this are:
 * intel_crtc_compute_config() --- Will presumably move to check_crtc()
   once we're farther along with atomic conversion.
 * intel_atomic_check() --- Handles updates via atomic ioctl (will also
   handle legacy plane updates once we switch to full atomic helpers)
 * skylake_pfit_update()

Since we're on transitional plane helpers today (which don't create a
top-level atomic transaction and thus never call intel_atomic_check),
does this ever get called for legacy SetPlane() operations on today's
driver?  Is it correct to assume that the switch back to full atomic
helpers is a prereq for merging this, or am I overlooking something?


Matt

> ---
>  drivers/gpu/drm/i915/intel_atomic.c |  142 +++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_drv.h    |    3 +
>  2 files changed, 145 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_atomic.c b/drivers/gpu/drm/i915/intel_atomic.c
> index 3903b90..fab1f13 100644
> --- a/drivers/gpu/drm/i915/intel_atomic.c
> +++ b/drivers/gpu/drm/i915/intel_atomic.c
> @@ -241,3 +241,145 @@ intel_crtc_destroy_state(struct drm_crtc *crtc,
>  {
>  	drm_atomic_helper_crtc_destroy_state(crtc, state);
>  }
> +
> +/**
> + * intel_atomic_setup_scalers() - setup scalers for crtc per staged requests
> + * @dev: DRM device
> + * @crtc: intel crtc
> + * @crtc_state: incoming crtc_state to validate and setup scalers
> + *
> + * This function sets up scalers based on staged scaling requests for
> + * a @crtc and its planes. It is called from crtc level check path. If request
> + * is a supportable request, it attaches scalers to requested planes and crtc.
> + *
> + * This function takes into account the current scaler(s) in use by any planes
> + * not being part of this atomic state
> + *
> + *  Returns:
> + *         0 - scalers were setup succesfully
> + *         error code - otherwise
> + */
> +int intel_atomic_setup_scalers(struct drm_device *dev,
> +	struct intel_crtc *intel_crtc,
> +	struct intel_crtc_state *crtc_state)
> +{
> +	struct drm_plane *plane = NULL;
> +	struct intel_plane *intel_plane;
> +	struct intel_plane_state *plane_state = NULL;
> +	struct intel_crtc_scaler_state *scaler_state;
> +	struct drm_atomic_state *drm_state;
> +	int num_scalers_need;
> +	int i, j;
> +
> +	if (INTEL_INFO(dev)->gen < 9 || !intel_crtc || !crtc_state)
> +		return 0;
> +
> +	scaler_state = &crtc_state->scaler_state;
> +	drm_state = crtc_state->base.state;
> +
> +	num_scalers_need = hweight32(scaler_state->scaler_users);
> +	DRM_DEBUG_KMS("crtc_state = %p need = %d avail = %d scaler_users = 0x%x\n",
> +		crtc_state, num_scalers_need, scaler_state->num_scalers,
> +		scaler_state->scaler_users);
> +
> +	/* if there is no change in scaler configuration, return */
> +	if (scaler_state->scaler_users ==
> +		intel_crtc->config->scaler_state.scaler_users)
> +		return 0;
> +
> +	/*
> +	 * High level flow:
> +	 * - staged scaler requests are already in scaler_state->scaler_users
> +	 * - check whether staged scaling requests can be supported
> +	 * - add planes using scalers that aren't in current transaction
> +	 * - assign scalers to requested users
> +	 * - as part of plane commit, scalers will be committed
> +	 *   (i.e., either attached or detached) to respective planes in hw
> +	 * - as part of crtc_commit, scaler will be either attached or detached
> +	 *   to crtc in hw
> +	 */
> +
> +	/* fail if required scalers > available scalers */
> +	if (num_scalers_need > scaler_state->num_scalers){
> +		DRM_DEBUG_KMS("Too many scaling requests %d > %d\n",
> +			num_scalers_need, scaler_state->num_scalers);
> +		return -EINVAL;
> +	}
> +
> +	/* walkthrough scaler_users bits and start assigning scalers */
> +	for (i = 0; i < sizeof(scaler_state->scaler_users) * 8; i++) {
> +		int *scaler_id;
> +
> +		/* skip if scaler not required */
> +		if (!(scaler_state->scaler_users & (1 << i)))
> +			continue;
> +
> +		if (i == SKL_CRTC_INDEX) {
> +			/* panel fitter case: assign as a crtc scaler */
> +			scaler_id = &scaler_state->scaler_id;
> +		} else {
> +			if (!drm_state)
> +				continue;
> +
> +			/* plane scaler case: assign as a plane scaler */
> +			/* find the plane that set the bit as scaler_user */
> +			plane = drm_state->planes[i];
> +
> +			/*
> +			 * to enable/disable hq mode, add planes that are using scaler
> +			 * into this transaction
> +			 */
> +			if (!plane) {
> +				struct drm_plane_state *state;
> +				plane = drm_plane_from_index(dev, i);
> +				state = drm_atomic_get_plane_state(drm_state, plane);
> +				if (IS_ERR(state)) {
> +					DRM_DEBUG_KMS("Failed to add [PLANE:%d] to drm_state\n",
> +						plane->base.id);
> +					return PTR_ERR(state);
> +				}
> +			}
> +
> +			intel_plane = to_intel_plane(plane);
> +
> +			/* plane on different crtc cannot be a scaler user of this crtc */
> +			if (WARN_ON(intel_plane->pipe != intel_crtc->pipe)) {
> +				continue;
> +			}
> +
> +			plane_state = to_intel_plane_state(drm_state->plane_states[i]);
> +			scaler_id = &plane_state->scaler_id;
> +		}
> +
> +		if (*scaler_id < 0) {
> +			/* find a free scaler */
> +			for (j = 0; j < scaler_state->num_scalers; j++) {
> +				if (!scaler_state->scalers[j].in_use) {
> +					scaler_state->scalers[j].in_use = 1;
> +					*scaler_id = scaler_state->scalers[j].id;
> +					DRM_DEBUG_KMS("Attached scaler id %u.%u to %s:%d\n",
> +						intel_crtc->pipe,
> +						i == SKL_CRTC_INDEX ? scaler_state->scaler_id :
> +							plane_state->scaler_id,
> +						i == SKL_CRTC_INDEX ? "CRTC" : "PLANE",
> +						i == SKL_CRTC_INDEX ?  intel_crtc->base.base.id :
> +						plane->base.id);
> +					break;
> +				}
> +			}
> +		}
> +
> +		if (WARN_ON(*scaler_id < 0)) {
> +			DRM_DEBUG_KMS("Cannot find scaler for %s:%d\n",
> +				i == SKL_CRTC_INDEX ? "CRTC" : "PLANE",
> +				i == SKL_CRTC_INDEX ? intel_crtc->base.base.id:plane->base.id);
> +			continue;
> +		}
> +
> +		/* set scaler mode */
> +		scaler_state->scalers[*scaler_id].mode = (num_scalers_need == 1) ?
> +			PS_SCALER_MODE_HQ : PS_SCALER_MODE_DYN;
> +	}
> +
> +	return 0;
> +}
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index e20ddd5..1381d11 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1407,6 +1407,9 @@ intel_atomic_get_crtc_state(struct drm_atomic_state *state,
>  
>  	return to_intel_crtc_state(crtc_state);
>  }
> +int intel_atomic_setup_scalers(struct drm_device *dev,
> +	struct intel_crtc *intel_crtc,
> +	struct intel_crtc_state *crtc_state);
>  
>  /* intel_atomic_plane.c */
>  struct intel_plane_state *intel_create_plane_state(struct drm_plane *plane);
> -- 
> 1.7.9.5
> 

-- 
Matt Roper
Graphics Software Engineer
IoTG Platform Enabling & Development
Intel Corporation
(916) 356-2795
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