Re: [REPOST PATCH v4 02/13] drm/msm/dsi: Pass DSC params to drm_panel

[Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>]

On 2/21/2022 4:37 AM, Dmitry Baryshkov wrote:
> On 10/02/2022 13:34, Vinod Koul wrote:
> > When DSC is enabled, we need to pass the DSC parameters to panel driver
> > as well, so add a dsc parameter in panel and set it when DSC is enabled
> >
> > Also, fetch and pass DSC configuration for DSI panels to DPU encoder,
> > which will enable and configure DSC hardware blocks accordingly.
> >
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> > Signed-off-by: Vinod Koul <vkoul@xxxxxxxxxx>
> > ---
> >   drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c |  2 ++
> >   drivers/gpu/drm/msm/dsi/dsi.c           |  5 +++++
> >   drivers/gpu/drm/msm/dsi/dsi.h           |  1 +
> >   drivers/gpu/drm/msm/dsi/dsi_host.c      | 22 ++++++++++++++++++++++
> >   drivers/gpu/drm/msm/msm_drv.h           |  8 ++++++++
> >   include/drm/drm_panel.h                 |  7 +++++++
> >   6 files changed, 45 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c 
> > b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > index 47fe11a84a77..ef6ddac22767 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > @@ -578,6 +578,8 @@ static int _dpu_kms_initialize_dsi(struct 
> > drm_device *dev,
> >               MSM_DISPLAY_CAP_CMD_MODE :
> >               MSM_DISPLAY_CAP_VID_MODE;
> > +        info.dsc = msm_dsi_get_dsc_config(priv->dsi[i]);
> > +
> >           if (msm_dsi_is_bonded_dsi(priv->dsi[i]) && priv->dsi[other]) {
> >               rc = msm_dsi_modeset_init(priv->dsi[other], dev, encoder);
> >               if (rc) {
> > diff --git a/drivers/gpu/drm/msm/dsi/dsi.c 
> > b/drivers/gpu/drm/msm/dsi/dsi.c
> > index 052548883d27..3aeac15e7421 100644
> > --- a/drivers/gpu/drm/msm/dsi/dsi.c
> > +++ b/drivers/gpu/drm/msm/dsi/dsi.c
> > @@ -20,6 +20,11 @@ bool msm_dsi_is_cmd_mode(struct msm_dsi *msm_dsi)
> >       return !(host_flags & MIPI_DSI_MODE_VIDEO);
> >   }
> > +struct msm_display_dsc_config *msm_dsi_get_dsc_config(struct msm_dsi 
> > *msm_dsi)
> > +{
> > +    return msm_dsi_host_get_dsc_config(msm_dsi->host);
> > +}
> > +
> >   static int dsi_get_phy(struct msm_dsi *msm_dsi)
> >   {
> >       struct platform_device *pdev = msm_dsi->pdev;
> > diff --git a/drivers/gpu/drm/msm/dsi/dsi.h 
> > b/drivers/gpu/drm/msm/dsi/dsi.h
> > index c8dedc95428c..16cd9b2fce86 100644
> > --- a/drivers/gpu/drm/msm/dsi/dsi.h
> > +++ b/drivers/gpu/drm/msm/dsi/dsi.h
> > @@ -152,6 +152,7 @@ int dsi_calc_clk_rate_v2(struct msm_dsi_host 
> > *msm_host, bool is_bonded_dsi);
> >   int dsi_calc_clk_rate_6g(struct msm_dsi_host *msm_host, bool 
> > is_bonded_dsi);
> >   void msm_dsi_host_snapshot(struct msm_disp_state *disp_state, struct 
> > mipi_dsi_host *host);
> >   void msm_dsi_host_test_pattern_en(struct mipi_dsi_host *host);
> > +struct msm_display_dsc_config *msm_dsi_host_get_dsc_config(struct 
> > mipi_dsi_host *host);
> >   /* dsi phy */
> >   struct msm_dsi_phy;
> > diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c 
> > b/drivers/gpu/drm/msm/dsi/dsi_host.c
> > index 27553194f9fa..7e9913eff724 100644
> > --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
> > +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
> > @@ -2059,9 +2059,24 @@ int msm_dsi_host_modeset_init(struct 
> > mipi_dsi_host *host,
> >   {
> >       struct msm_dsi_host *msm_host = to_msm_dsi_host(host);
> >       const struct msm_dsi_cfg_handler *cfg_hnd = msm_host->cfg_hnd;
> > +    struct drm_panel *panel;
> >       int ret;
> >       msm_host->dev = dev;
> > +    panel = msm_dsi_host_get_panel(&msm_host->base);
> > +
> > +    if (panel && panel->dsc) {
> > +        struct msm_display_dsc_config *dsc = msm_host->dsc;
> > +
> > +        if (!dsc) {
> > +            dsc = devm_kzalloc(&msm_host->pdev->dev, sizeof(*dsc), 
> > GFP_KERNEL);
> > +            if (!dsc)
> > +                return -ENOMEM;
> > +            dsc->drm = panel->dsc;
> > +            msm_host->dsc = dsc;
> > +        }
> > +    }
> > +
> >       ret = cfg_hnd->ops->tx_buf_alloc(msm_host, SZ_4K);
> >       if (ret) {
> >           pr_err("%s: alloc tx gem obj failed, %d\n", __func__, ret);
> > @@ -2626,3 +2641,10 @@ void msm_dsi_host_test_pattern_en(struct 
> > mipi_dsi_host *host)
> >           dsi_write(msm_host, 
> > REG_DSI_TEST_PATTERN_GEN_CMD_STREAM0_TRIGGER,
> >                   DSI_TEST_PATTERN_GEN_CMD_STREAM0_TRIGGER_SW_TRIGGER);
> >   }
> > +
> > +struct msm_display_dsc_config *msm_dsi_host_get_dsc_config(struct 
> > mipi_dsi_host *host)
> > +{
> > +    struct msm_dsi_host *msm_host = to_msm_dsi_host(host);
> > +
> > +    return msm_host->dsc;
> > +}
> > diff --git a/drivers/gpu/drm/msm/msm_drv.h 
> > b/drivers/gpu/drm/msm/msm_drv.h
> > index 384f9bad4760..e7a312edfe67 100644
> > --- a/drivers/gpu/drm/msm/msm_drv.h
> > +++ b/drivers/gpu/drm/msm/msm_drv.h
> > @@ -119,6 +119,7 @@ struct msm_display_topology {
> >    *                      based on num_of_h_tiles
> >    * @is_te_using_watchdog_timer:  Boolean to indicate watchdog TE is
> >    *                 used instead of panel TE in cmd mode panels
> > + * @dsc:        DSC configuration data for DSC-enabled displays
> >    */
> >   struct msm_display_info {
> >       int intf_type;
> > @@ -126,6 +127,7 @@ struct msm_display_info {
> >       uint32_t num_of_h_tiles;
> >       uint32_t h_tile_instance[MAX_H_TILES_PER_DISPLAY];
> >       bool is_te_using_watchdog_timer;
> > +    struct msm_display_dsc_config *dsc;
> >   };
> >   /* Commit/Event thread specific structure */
> > @@ -365,6 +367,7 @@ void msm_dsi_snapshot(struct msm_disp_state 
> > *disp_state, struct msm_dsi *msm_dsi
> >   bool msm_dsi_is_cmd_mode(struct msm_dsi *msm_dsi);
> >   bool msm_dsi_is_bonded_dsi(struct msm_dsi *msm_dsi);
> >   bool msm_dsi_is_master_dsi(struct msm_dsi *msm_dsi);
> > +struct msm_display_dsc_config *msm_dsi_get_dsc_config(struct msm_dsi 
> > *msm_dsi);
> >   #else
> >   static inline void __init msm_dsi_register(void)
> >   {
> > @@ -393,6 +396,11 @@ static inline bool msm_dsi_is_master_dsi(struct 
> > msm_dsi *msm_dsi)
> >   {
> >       return false;
> >   }
> > +
> > +static inline struct msm_display_dsc_config 
> > *msm_dsi_get_dsc_config(struct msm_dsi *msm_dsi)
> > +{
> > +    return NULL;
> > +}
> >   #endif
> >   #ifdef CONFIG_DRM_MSM_DP
> > diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h
> > index 4602f833eb51..eb8ae9bf32ed 100644
> > --- a/include/drm/drm_panel.h
> > +++ b/include/drm/drm_panel.h
> > @@ -171,6 +171,13 @@ struct drm_panel {
> >        * Panel entry in registry.
> >        */
> >       struct list_head list;
> > +
> > +    /**
> > +     * @dsc:
> > +     *
> > +     * Panel DSC pps payload to be sent
> > +     */
> > +    struct drm_dsc_config *dsc;
>
> This is not a blocker or a request for a change, just a kind of thought:
>
> I've been looking onto this change for a while from the following point 
> of view. I'd like to switch DSI driver to use panel 
> bridge/drm_bridge_connector(). This simplifies handling of DRM bridge 
> chains.
>
> Also since DSC can be consumed not by the panel itself, but by the next 
> bridge in chain (e.g. it's supported on the DSI input by the ANX7625 
> bridge), using drm_panel doesn't look completely correct.
>
> So, I have been looking for a better way to pass DSC configuration.
>
> For DSI we can use struct mipi_dsi_device (together with the rest of 
> data we are passing from DSI device driver to DSI host). This would 
> allow both DSI panels and DSI bridges to pass the DSC config to the 
> previous deivce in chain (DSI host).
>
> Any comments/thoughs?
>
> Note, for DP this problem doesn't exist. The DSC config is a part of 
> DPDC, so it will be parsed by the msm/dp driver in a natural way.

Yes, i do agree that in case of bridges in between , drm_panel is not 
necessarily the best place to do it and mipi_dsi_device is better.

However, I also think we can do this post the cleanup fo move to panel 
bridge.

> >   };
> >   void drm_panel_init(struct drm_panel *panel, struct device *dev,