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

[kalyan_t@codeaurora.org]

On 2020-08-05 01:02, Rob Clark wrote:
> On Tue, Aug 4, 2020 at 4:32 AM Kalyan Thota <kalyan_t@codeaurora.org> 
> 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@codeaurora.org>
>> ---
>>  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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