linux-kernel - Re: [PATCH v3 2/4] drm/msm/dpu: Enable widebus for DSI INTF

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Date:   Mon, 7 Aug 2023 14:40:31 -0700
From:   Jessica Zhang <quic_jesszhan@...cinc.com>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC:     Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        "Marijn Suijten" <marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>, <quic_abhinavk@...cinc.com>,
        <linux-arm-msm@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>,
        <freedreno@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 2/4] drm/msm/dpu: Enable widebus for DSI INTF



On 8/2/2023 11:20 AM, Dmitry Baryshkov wrote:
> On Wed, 2 Aug 2023 at 21:09, Jessica Zhang <quic_jesszhan@...cinc.com> wrote:
>>
>> DPU supports a data-bus widen mode for DSI INTF.
>>
>> Enable this mode for all supported chipsets if widebus is enabled for DSI.
>>
>> Signed-off-by: Jessica Zhang <quic_jesszhan@...cinc.com>
>> ---
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c          | 11 ++++++++---
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c |  4 +++-
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c          |  3 +++
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h          |  1 +
>>   drivers/gpu/drm/msm/msm_drv.h                        |  6 +++++-
>>   5 files changed, 20 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>> index 3dcd37c48aac..de08aad39e15 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>> @@ -1196,15 +1196,20 @@ static void dpu_encoder_virt_atomic_enable(struct drm_encoder *drm_enc,
>>          struct drm_display_mode *cur_mode = NULL;
>>          struct msm_drm_private *priv = drm_enc->dev->dev_private;
>>          struct msm_display_info *disp_info;
>> +       int index;
>>
>>          dpu_enc = to_dpu_encoder_virt(drm_enc);
>>          disp_info = &dpu_enc->disp_info;
>>
>> +       disp_info = &dpu_enc->disp_info;
>> +       index = disp_info->h_tile_instance[0];
>> +
>>          dpu_enc->dsc = dpu_encoder_get_dsc_config(drm_enc);
>>
>> -       if (disp_info->intf_type == INTF_DP)
>> -               dpu_enc->wide_bus_en = msm_dp_wide_bus_available(
>> -                               priv->dp[disp_info->h_tile_instance[0]]);
>> +       if (disp_info->intf_type == INTF_DSI)
>> +               dpu_enc->wide_bus_en = msm_dsi_is_widebus_enabled(priv->dsi[index]);
>> +       else if (disp_info->intf_type == INTF_DP)
>> +               dpu_enc->wide_bus_en = msm_dp_wide_bus_available(priv->dp[index]);
> 
> If you change the order, you won't have to touch DP lines.

Hi Dmitry,

Acked.

> 
>>
>>          mutex_lock(&dpu_enc->enc_lock);
>>          cur_mode = &dpu_enc->base.crtc->state->adjusted_mode;
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
>> index df88358e7037..dace6168be2d 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
>> @@ -69,8 +69,10 @@ static void _dpu_encoder_phys_cmd_update_intf_cfg(
>>                                  phys_enc->hw_intf,
>>                                  phys_enc->hw_pp->idx);
>>
>> -       if (intf_cfg.dsc != 0)
>> +       if (intf_cfg.dsc != 0) {
>>                  cmd_mode_cfg.data_compress = true;
>> +               cmd_mode_cfg.wide_bus_en = dpu_encoder_is_widebus_enabled(phys_enc->parent);
>> +       }
> 
> This embeds the knowledge that a wide bus can only be enabled when DSC
> is in use. Please move the wide_bus_en assignment out of conditional
> code.

Wide bus for DSI will only be enabled if DSC is enabled, so this is 
technically not wrong, as DP will use the video mode path.

> 
>>
>>          if (phys_enc->hw_intf->ops.program_intf_cmd_cfg)
>>                  phys_enc->hw_intf->ops.program_intf_cmd_cfg(phys_enc->hw_intf, &cmd_mode_cfg);
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
>> index 8ec6505d9e78..dc6f3febb574 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
>> @@ -521,6 +521,9 @@ static void dpu_hw_intf_program_intf_cmd_cfg(struct dpu_hw_intf *ctx,
> 
> This function is only enabled for DPU >= 7.0, while IIRC wide bus can
> be enabled even for some of the earlier chipsets.

The command mode path is only called for DSI, which only supports wide 
bus for DPU 7.0+.

> 
>>          if (cmd_mode_cfg->data_compress)
>>                  intf_cfg2 |= INTF_CFG2_DCE_DATA_COMPRESS;
>>
>> +       if (cmd_mode_cfg->wide_bus_en)
>> +               intf_cfg2 |= INTF_CFG2_DATABUS_WIDEN;
>> +
>>          DPU_REG_WRITE(&ctx->hw, INTF_CONFIG2, intf_cfg2);
>>   }
>>
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h
>> index 77f80531782b..c539025c418b 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h
>> @@ -50,6 +50,7 @@ struct dpu_hw_intf_status {
>>
>>   struct dpu_hw_intf_cmd_mode_cfg {
>>          u8 data_compress;       /* enable data compress between dpu and dsi */
>> +       u8 wide_bus_en;         /* enable databus widen mode */
>>   };
>>
>>   /**
>> diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
>> index 9d9d5e009163..e4f706b16aad 100644
>> --- a/drivers/gpu/drm/msm/msm_drv.h
>> +++ b/drivers/gpu/drm/msm/msm_drv.h
>> @@ -344,6 +344,7 @@ 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);
>> +bool msm_dsi_is_widebus_enabled(struct msm_dsi *msm_dsi);
>>   struct drm_dsc_config *msm_dsi_get_dsc_config(struct msm_dsi *msm_dsi);
>>   #else
>>   static inline void __init msm_dsi_register(void)
>> @@ -373,7 +374,10 @@ static inline bool msm_dsi_is_master_dsi(struct msm_dsi *msm_dsi)
>>   {
>>          return false;
>>   }
>> -
>> +static inline bool msm_dsi_is_widebus_enabled(struct msm_dsi *msm_dsi)
>> +{
>> +       return false;
>> +}
> 
> Empty line, please.

Acked.

Thanks,

Jessica Zhang

> 
>>   static inline struct drm_dsc_config *msm_dsi_get_dsc_config(struct msm_dsi *msm_dsi)
>>   {
>>          return NULL;
>>
>> --
>> 2.41.0
>>
> 
> 
> -- 
> With best wishes
> Dmitry