Re: [Freedreno] [v1] drm/msm/dpu: update reservations in commit path

[kalyan_t]

On 2020-08-05 01:02, Rob Clark wrote:
> On Tue, Aug 4, 2020 at 4:32 AM Kalyan Thota <kalyan_t@xxxxxxxxxxxxxx> 
> wrote:
> > DPU resources reserved in the atomic_check path gets unwinded
> > during modeset operation before commit happens in a non seamless
> > transition.
> >
> > Update the reservations in the commit path to avoid resource
> > failures. Secondly have dummy reservations in atomic_check path
> > so that we can gracefully fail the composition if resources are
> > not available.
> >
> > Signed-off-by: Kalyan Thota <kalyan_t@xxxxxxxxxxxxxx>
> > ---
> >  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 15 +++++++++++----
> >  1 file changed, 11 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c 
> > b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > index 63976dc..c6b8254 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > @@ -565,7 +565,7 @@ static int dpu_encoder_virt_atomic_check(
> >         const struct drm_display_mode *mode;
> >         struct drm_display_mode *adj_mode;
> >         struct msm_display_topology topology;
> > -       struct dpu_global_state *global_state;
> > +       struct dpu_global_state tmp_resv_state;
> >         int i = 0;
> >         int ret = 0;
> >
> > @@ -582,7 +582,7 @@ static int dpu_encoder_virt_atomic_check(
> >         dpu_kms = to_dpu_kms(priv->kms);
> >         mode = &crtc_state->mode;
> >         adj_mode = &crtc_state->adjusted_mode;
> > -       global_state = dpu_kms_get_existing_global_state(dpu_kms);
> > +       memset(&tmp_resv_state, 0, sizeof(tmp_resv_state));
>
> I think what you want to do is dpu_kms_get_global_state().. that will
> clone/duplicate the existing global state (or return the already
> duplicated global state if it is called multiple times).
Thanks Rob, realized the same after posting patch. Made changes in the 
new patch
accordingly.

> It is safe to modify this global state in the atomic_check() path.. in
> fact that is the intention.  For a TEST_ONLY atomic commit, or if any
> of the atomic_check()'s fail, this new duplicated global state is
> discarded.  If all the checks succeed and the atomic update is
> committed to hw, this new global state replaces the existing global
> state.
Posted a new change kindly review.

> BR,
> -R
>
> >         trace_dpu_enc_atomic_check(DRMID(drm_enc));
> >
> >         /*
> > @@ -621,7 +621,7 @@ static int dpu_encoder_virt_atomic_check(
> >                  * info may not be available to complete reservation.
> >                  */
> >                 if (drm_atomic_crtc_needs_modeset(crtc_state)) {
> > -                       ret = dpu_rm_reserve(&dpu_kms->rm, 
> > global_state,
> > +                       ret = dpu_rm_reserve(&dpu_kms->rm, 
> > &tmp_resv_state,
> >                                         drm_enc, crtc_state, 
> > topology);
> >                 }
> >         }
> > @@ -966,7 +966,7 @@ static void dpu_encoder_virt_mode_set(struct 
> > drm_encoder *drm_enc,
> >         struct dpu_hw_blk *hw_lm[MAX_CHANNELS_PER_ENC];
> >         struct dpu_hw_blk *hw_dspp[MAX_CHANNELS_PER_ENC] = { NULL };
> >         int num_lm, num_ctl, num_pp, num_dspp;
> > -       int i, j;
> > +       int i, j, rc;
> >
> >         if (!drm_enc) {
> >                 DPU_ERROR("invalid encoder\n");
> > @@ -1006,6 +1006,13 @@ static void dpu_encoder_virt_mode_set(struct 
> > drm_encoder *drm_enc,
> >
> >         topology = dpu_encoder_get_topology(dpu_enc, dpu_kms, 
> > adj_mode);
> >
> > +       rc = dpu_rm_reserve(&dpu_kms->rm, global_state, drm_enc,
> > +               drm_crtc->state, topology);
> > +       if (rc) {
> > +               DPU_ERROR_ENC(dpu_enc, "Failed to reserve 
> > resources\n");
> > +               return;
> > +       }
> > +
> >         /* Query resource that have been reserved in atomic check 
> > step. */
> >         num_pp = dpu_rm_get_assigned_resources(&dpu_kms->rm, 
> > global_state,
> >                 drm_enc->base.id, DPU_HW_BLK_PINGPONG, hw_pp,
> > --
> > 1.9.1
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