linux-kernel - Re: [PATCH 1/4] drm/msm/dpu: Introduce knowledge of widebus feature

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Date:   Thu, 13 May 2021 02:14:27 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        "open list:DRM DRIVER FOR MSM ADRENO GPU" 
        <linux-arm-msm@...r.kernel.org>,
        "open list:DRM DRIVER FOR MSM ADRENO GPU" 
        <dri-devel@...ts.freedesktop.org>,
        freedreno <freedreno@...ts.freedesktop.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/4] drm/msm/dpu: Introduce knowledge of widebus feature

On Tue, 11 May 2021 at 07:18, Bjorn Andersson
<bjorn.andersson@...aro.org> wrote:
>
> Some hardware supports clocking 2 pixels per pixel clock pulse, known as
> "widebus". The configuration needs to match between the DPU and the
> interface controller, and the timing parameters must be adjusted.
>
> As a first step towards supporting this, start by adding a INTF mask
> flag to signal the timing configuration code that the INTF_CONFIG2
> register should be written - which will clear the bit, in the case that
> the bootloader left it set.
>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>

> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h | 2 ++
>  drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c    | 3 ++-
>  2 files changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h
> index 4dfd8a20ad5c..c2f34a4f82d9 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h
> @@ -196,12 +196,14 @@ enum {
>   * @DPU_INTF_TE                 INTF block has TE configuration support
>   * @DPU_DATA_HCTL_EN            Allows data to be transferred at different rate
>                                  than video timing
> + * @DPU_INTF_WIDEBUS            INTF block supports driving 2 pixels per clock
>   * @DPU_INTF_MAX
>   */
>  enum {
>         DPU_INTF_INPUT_CTRL = 0x1,
>         DPU_INTF_TE,
>         DPU_DATA_HCTL_EN,
> +       DPU_INTF_WIDEBUS,
>         DPU_INTF_MAX
>  };
>
> 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 1599e3f49a4f..933485d8c03c 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
> @@ -183,7 +183,6 @@ static void dpu_hw_intf_setup_timing_engine(struct dpu_hw_intf *ctx,
>         if (ctx->cap->features & BIT(DPU_DATA_HCTL_EN)) {
>                 intf_cfg2 |= BIT(4);
>                 display_data_hctl = display_hctl;
> -               DPU_REG_WRITE(c, INTF_CONFIG2, intf_cfg2);
>                 DPU_REG_WRITE(c, INTF_DISPLAY_DATA_HCTL, display_data_hctl);
>         }
>
> @@ -204,6 +203,8 @@ static void dpu_hw_intf_setup_timing_engine(struct dpu_hw_intf *ctx,
>         DPU_REG_WRITE(c, INTF_FRAME_LINE_COUNT_EN, 0x3);
>         DPU_REG_WRITE(c, INTF_CONFIG, intf_cfg);
>         DPU_REG_WRITE(c, INTF_PANEL_FORMAT, panel_format);
> +       if (ctx->cap->features & (BIT(DPU_DATA_HCTL_EN) | BIT(DPU_INTF_WIDEBUS)))
> +               DPU_REG_WRITE(c, INTF_CONFIG2, intf_cfg2);
>  }
>
>  static void dpu_hw_intf_enable_timing_engine(
> --
> 2.29.2
>


-- 
With best wishes
Dmitry