Re: [PATCH v3 4/4] drm/msm/dsi: Enable widebus for DSI

[Dmitry Baryshkov]

On Wed, 2 Aug 2023 at 21:09, Jessica Zhang <quic_jesszhan@xxxxxxxxxxx> wrote:
>
> DSI 6G v2.5.x+ supports a data-bus widen mode that allows DSI to send
> 48 bits of compressed data instead of 24.
>
> Enable this mode whenever DSC is enabled for supported chipsets.
>
> Signed-off-by: Jessica Zhang <quic_jesszhan@xxxxxxxxxxx>
> ---
>  drivers/gpu/drm/msm/dsi/dsi.c      |  5 +++++
>  drivers/gpu/drm/msm/dsi/dsi.h      |  1 +
>  drivers/gpu/drm/msm/dsi/dsi_host.c | 30 ++++++++++++++++++++++++++----
>  3 files changed, 32 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dsi/dsi.c b/drivers/gpu/drm/msm/dsi/dsi.c
> index baab79ab6e74..4fa738dea680 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi.c
> @@ -17,6 +17,11 @@ struct drm_dsc_config *msm_dsi_get_dsc_config(struct msm_dsi *msm_dsi)
>         return msm_dsi_host_get_dsc_config(msm_dsi->host);
>  }
>
> +bool msm_dsi_is_widebus_enabled(struct msm_dsi *msm_dsi)
> +{
> +       return msm_dsi_host_is_widebus_enabled(msm_dsi->host);
> +}

If this function is not provided at the time of the previous patch,
compilation will break. I'd suggest to provide a stub first and then
change it in this patch.

> +
>  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 bd3763a5d723..a557d2c1aaff 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi.h
> +++ b/drivers/gpu/drm/msm/dsi/dsi.h
> @@ -134,6 +134,7 @@ 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 drm_dsc_config *msm_dsi_host_get_dsc_config(struct mipi_dsi_host *host);
> +bool msm_dsi_host_is_widebus_enabled(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 645927214871..231b02e5ab6e 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
> @@ -710,6 +710,14 @@ static void dsi_ctrl_disable(struct msm_dsi_host *msm_host)
>         dsi_write(msm_host, REG_DSI_CTRL, 0);
>  }
>
> +bool msm_dsi_host_is_widebus_enabled(struct mipi_dsi_host *host)
> +{
> +       struct msm_dsi_host *msm_host = to_msm_dsi_host(host);
> +
> +       return msm_host->dsc && (msm_host->cfg_hnd->major == MSM_DSI_VER_MAJOR_6G &&

Please add a line break after the first &&. Compare two following statements:

> +                       msm_host->cfg_hnd->minor >= MSM_DSI_6G_VER_MINOR_V2_5_0);
> +}
> +
>  static void dsi_ctrl_enable(struct msm_dsi_host *msm_host,
>                         struct msm_dsi_phy_shared_timings *phy_shared_timings, struct msm_dsi_phy *phy)
>  {
> @@ -753,10 +761,16 @@ static void dsi_ctrl_enable(struct msm_dsi_host *msm_host,
>                 data |= DSI_CMD_CFG1_INSERT_DCS_COMMAND;
>                 dsi_write(msm_host, REG_DSI_CMD_CFG1, data);
>
> -               if (msm_host->cfg_hnd->major == MSM_DSI_VER_MAJOR_6G &&
> -                   msm_host->cfg_hnd->minor >= MSM_DSI_6G_VER_MINOR_V1_3) {
> +               if (cfg_hnd->major == MSM_DSI_VER_MAJOR_6G) {
>                         data = dsi_read(msm_host, REG_DSI_CMD_MODE_MDP_CTRL2);
> -                       data |= DSI_CMD_MODE_MDP_CTRL2_BURST_MODE;
> +
> +                       if (cfg_hnd->minor >= MSM_DSI_6G_VER_MINOR_V1_3)
> +                               data |= DSI_CMD_MODE_MDP_CTRL2_BURST_MODE;
> +
> +                       /* TODO: Allow for video-mode support once tested/fixed */
> +                       if (msm_dsi_host_is_widebus_enabled(&msm_host->base))
> +                               data |= DSI_CMD_MODE_MDP_CTRL2_DATABUS_WIDEN;
> +
>                         dsi_write(msm_host, REG_DSI_CMD_MODE_MDP_CTRL2, data);
>                 }
>         }
> @@ -894,6 +908,7 @@ static void dsi_timing_setup(struct msm_dsi_host *msm_host, bool is_bonded_dsi)
>         u32 hdisplay = mode->hdisplay;
>         u32 wc;
>         int ret;
> +       bool widebus_enabled = msm_dsi_host_is_widebus_enabled(&msm_host->base);
>
>         DBG("");
>
> @@ -914,6 +929,7 @@ static void dsi_timing_setup(struct msm_dsi_host *msm_host, bool is_bonded_dsi)
>
>         if (msm_host->dsc) {
>                 struct drm_dsc_config *dsc = msm_host->dsc;
> +               u32 bytes_per_pclk;
>
>                 /* update dsc params with timing params */
>                 if (!dsc || !mode->hdisplay || !mode->vdisplay) {
> @@ -937,7 +953,13 @@ static void dsi_timing_setup(struct msm_dsi_host *msm_host, bool is_bonded_dsi)
>                  * pulse width same
>                  */
>                 h_total -= hdisplay;
> -               hdisplay = DIV_ROUND_UP(msm_dsc_get_bytes_per_line(msm_host->dsc), 3);
> +               if (widebus_enabled && !(msm_host->mode_flags & MIPI_DSI_MODE_VIDEO))
> +                       bytes_per_pclk = 6;
> +               else
> +                       bytes_per_pclk = 3;
> +
> +               hdisplay = DIV_ROUND_UP(msm_dsc_get_bytes_per_line(msm_host->dsc), bytes_per_pclk);
> +
>                 h_total += hdisplay;
>                 ha_end = ha_start + hdisplay;
>         }
>
> --
> 2.41.0
>


-- 
With best wishes
Dmitry