On Thu, Jan 16, 2025 at 03:26:05PM +0800, Jun Nie wrote:
> Request 4 mixers and 4 DSC for the case that both dual-DSI and DSC are
> enabled.
Why? What is the issue that you are solving?
> 4 pipes are preferred for dual DSI case for it is power optimal
> for DSC.
>
> Signed-off-by: Jun Nie <jun.nie@xxxxxxxxxx>
> ---
> drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 2 +-
> drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h | 6 ++---
> drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 29 ++++++++++++++++++------
> drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h | 2 +-
> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h | 2 +-
> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h | 2 +-
> 6 files changed, 29 insertions(+), 14 deletions(-)
>
> @@ -664,15 +664,20 @@ static struct msm_display_topology dpu_encoder_get_topology(
>
> /* Datapath topology selection
> *
> - * Dual display
> + * Dual display without DSC
> * 2 LM, 2 INTF ( Split display using 2 interfaces)
> *
> + * Dual display with DSC
> + * 2 LM, 2 INTF ( Split display using 2 interfaces)
> + * 4 LM, 2 INTF ( Split display using 2 interfaces)
> + *
> * Single display
> * 1 LM, 1 INTF
> * 2 LM, 1 INTF (stream merge to support high resolution interfaces)
> *
> * Add dspps to the reservation requirements if ctm is requested
> */
> +
irrlevant extra line, please drop.
> if (intf_count == 2)
> topology.num_lm = 2;
> else if (!dpu_kms->catalog->caps->has_3d_merge)
> @@ -691,10 +696,20 @@ static struct msm_display_topology dpu_encoder_get_topology(
> * 2 DSC encoders, 2 layer mixers and 1 interface
> * this is power optimal and can drive up to (including) 4k
> * screens
> + * But for dual display case, we prefer 4 layer mixers. Because
> + * the resolution is always high in the case and 4 DSCs are more
> + * power optimal.
I think this part is thought about in a wrong way. If it was just about
power efficiency, we wouldn't have to add quad pipe support.
Please correct me if I'm wrong, but I think it is about the maximum
width supported by a particular topology being too low for a requested
resolution. So, if there is a DSC and mode width is higher than 5120
(8.x+) / 4096 ( <= 7.x), then we have to use quad pipe. Likewise if
there is no DSC in play, the limitation should be 2 * max_mixer_width.
> */
> - topology.num_dsc = 2;
> - topology.num_lm = 2;
> - topology.num_intf = 1;
> +
> + if (intf_count == 2) {
> + topology.num_dsc = dpu_kms->catalog->dsc_count >= 4 ? 4 : 2;
This assumes that the driver can support 2:2:2. Is it the case?
> + topology.num_lm = topology.num_dsc;
> + topology.num_intf = 2;
> + } else {
> + topology.num_dsc = 2;
> + topology.num_lm = 2;
> + topology.num_intf = 1;
> + }
> }
>
> return topology;
--
With best wishes
Dmitry
