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

Konduru, Chandra
2015-03-25T19:46:18Z

> -----Original Message-----
> From: Roper, Matthew D
> Sent: Tuesday, March 24, 2015 10:15 PM
> To: Konduru, Chandra
> Cc: intel-gfx@lists.freedesktop.org; Vetter, Daniel; Conselvan De Oliveira, Ander
> Subject: Re: [PATCH 09/21 v2] drm/i915: Add atomic function to setup scalers
> scalers for a crtc.
>
> 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/

Yes, will update.

>
> > + * 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?

Two reasons for having above check:
1) Yes, that is what expected in case of planes. But because current tree is not
having full atomic helpers, placed this check.
2) During legacy setmode requiring/freeing panel fitter, it can be null.
To cover those cases, placed this check for proper operation of scaler
for panel fitter.

>
> > +
> > + /* 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.

Ok, will return in case of error from drm_atomic_get_plane_state().
Will send updated patch shortly.

>
> > + }
> > +
> > + 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