Re: [PATCH 13/16] drm/msm/dpu: reserve cdm blocks for writeback in case of YUV output

[Dmitry Baryshkov]

On Thu, 31 Aug 2023 at 01:50, Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx> wrote:
>
> Reserve CDM blocks for writeback if the format of the output fb
> is YUV. At the moment, the reservation is done only for writeback
> but can easily be extended by relaxing the checks once other
> interfaces are ready to output YUV.
>
> Signed-off-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 35 ++++++++++++++++++++-
>  1 file changed, 34 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> index 1b1e07292a9e..7a3d179bdfba 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> @@ -16,6 +16,7 @@
>  #include <drm/drm_crtc.h>
>  #include <drm/drm_file.h>
>  #include <drm/drm_probe_helper.h>
> +#include <drm/drm_framebuffer.h>
>
>  #include "msm_drv.h"
>  #include "dpu_kms.h"
> @@ -615,9 +616,11 @@ static int dpu_encoder_virt_atomic_check(
>         struct drm_display_mode *adj_mode;
>         struct msm_display_topology topology;
>         struct dpu_global_state *global_state;
> +       struct drm_framebuffer *fb;
>         struct drm_dsc_config *dsc;
>         int i = 0;
>         int ret = 0;
> +       bool needs_cdm = false;
>
>         if (!drm_enc || !crtc_state || !conn_state) {
>                 DPU_ERROR("invalid arg(s), drm_enc %d, crtc/conn state %d/%d\n",
> @@ -655,6 +658,22 @@ static int dpu_encoder_virt_atomic_check(
>
>         topology = dpu_encoder_get_topology(dpu_enc, dpu_kms, adj_mode, crtc_state, dsc);
>
> +       /*
> +        * Use CDM only for writeback at the moment as other interfaces cannot handle it.
> +        * if writeback itself cannot handle cdm for some reason it will fail in its atomic_check()
> +        * earlier.
> +        */
> +       if (dpu_enc->disp_info.intf_type == INTF_WB && conn_state->writeback_job) {
> +               fb = conn_state->writeback_job->fb;
> +
> +               if (fb && DPU_FORMAT_IS_YUV(to_dpu_format(msm_framebuffer_format(fb))))
> +                       needs_cdm = true;
> +               if (needs_cdm && !dpu_enc->cur_master->hw_cdm)
> +                       crtc_state->mode_changed = true;
> +               else if (!needs_cdm && dpu_enc->cur_master->hw_cdm)
> +                       crtc_state->mode_changed = true;
> +       }

What would be the (estimated) check for DP?

> +
>         /*
>          * Release and Allocate resources on every modeset
>          * Dont allocate when active is false.
> @@ -664,7 +683,7 @@ static int dpu_encoder_virt_atomic_check(
>
>                 if (!crtc_state->active_changed || crtc_state->enable)
>                         ret = dpu_rm_reserve(&dpu_kms->rm, global_state,
> -                                       drm_enc, crtc_state, topology, false);
> +                                       drm_enc, crtc_state, topology, needs_cdm);
>         }
>
>         trace_dpu_enc_atomic_check_flags(DRMID(drm_enc), adj_mode->flags);
> @@ -1126,6 +1145,20 @@ static void dpu_encoder_virt_atomic_mode_set(struct drm_encoder *drm_enc,
>
>         dpu_enc->dsc_mask = dsc_mask;
>
> +       if (dpu_enc->disp_info.intf_type == INTF_WB && conn_state->writeback_job) {
> +               struct dpu_hw_blk *hw_cdm = NULL;
> +               struct drm_framebuffer *fb;
> +
> +               fb = conn_state->writeback_job->fb;
> +
> +               if (fb && DPU_FORMAT_IS_YUV(to_dpu_format(msm_framebuffer_format(fb)))) {

You can drop all fb-related conditions here. If we have CDM, we know
that we asked for it. If we do not, it's because we do not need it.

> +                       dpu_rm_get_assigned_resources(&dpu_kms->rm, global_state,
> +                                                     drm_enc->base.id, DPU_HW_BLK_CDM,
> +                                                     &hw_cdm, 1);
> +               }
> +               dpu_enc->cur_master->hw_cdm = hw_cdm ? to_dpu_hw_cdm(hw_cdm) : NULL;
> +       }
> +
>         cstate = to_dpu_crtc_state(crtc_state);
>
>         for (i = 0; i < num_lm; i++) {
> --
> 2.40.1
>


-- 
With best wishes
Dmitry