Re: [PATCH 09/21 v2] drm/i915: Add atomic function to setup scalers scalers for a crtc.

Matt Roper
2015-03-25T05:15:18Z

On Fri, Mar 20, 2015 at 05:04:30PM -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)
>
> Signed-off-by: Chandra Konduru <chandra.konduru@intel.com>
> ---
> drivers/gpu/drm/i915/intel_atomic.c | 138 +++++++++++++++++++++++++++++++++++
> drivers/gpu/drm/i915/intel_drv.h | 3 +
> 2 files changed, 141 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_atomic.c b/drivers/gpu/drm/i915/intel_atomic.c
> index 3903b90..407516a 100644
> --- a/drivers/gpu/drm/i915/intel_atomic.c
> +++ b/drivers/gpu/drm/i915/intel_atomic.c
> @@ -241,3 +241,141 @@ 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 setups up scalers based on staged scaling requests for

s/setups up/sets up/

> + * 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;

This shouldn't happen, at least not once we're back on the full atomic
helpers, right? It seems like if it does happen, nothing's going to
work right, so maybe add a WARN_ON() to this test?

> +
> + /* 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) {
> + plane = drm_plane_from_index(dev, i);
> + drm_state->planes[i] = plane;
> + drm_state->plane_states[i] =
> + drm_atomic_get_plane_state(drm_state, plane);

I think you need to test for EDEADLK here in case we have a w/w
collision. Other errors like ENOMEM might also happen. Actually,
drm_atomic_get_plane_state() will take care of adding the state to the
plane_states[] array for you, so no need for the assignment; you can
just call the function and check for error returns.

> + }
> +
> + 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 f5d53c9..a9d787d 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1401,6 +1401,9 @@ 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