linux-kernel - Re: [PATCH v8 12/15] drm/msm/disp/dpu: get timing engine status from intf status register

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Message-ID: <20221101121506.eyzsepukm6smwvxh@SoMainline.org>
Date:   Tue, 1 Nov 2022 13:15:06 +0100
From:   Marijn Suijten <marijn.suijten@...ainline.org>
To:     Vinod Polimera <quic_vpolimer@...cinc.com>
Cc:     dri-devel@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        freedreno@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, robdclark@...il.com,
        dianders@...omium.org, swboyd@...omium.org,
        quic_kalyant@...cinc.com, dmitry.baryshkov@...aro.org,
        quic_khsieh@...cinc.com, quic_vproddut@...cinc.com,
        quic_bjorande@...cinc.com, quic_aravindh@...cinc.com,
        quic_abhinavk@...cinc.com, quic_sbillaka@...cinc.com
Subject: Re: [PATCH v8 12/15] drm/msm/disp/dpu: get timing engine status from
 intf status register

On 2022-10-12 17:32:36, Vinod Polimera wrote:
> Timing gen status can be read reliablly from intf status

Typo. "reliably read from the intf status register..."

> register rather than from the timing gen control register,
> which will readback as "0" after disable though the timing
> gen is still under going disable path. This support was

undergoing*, and it's still rather unclear what behaviour you're trying
to describe.

It seems like you're stating that INTF_STATUS (in the first bit...) will
read zero when the timing engine (in hardware) has finished disabling
rather than reading zero as soon as dpu_hw_intf_enable_timing_engine()
writes a zero.

> added from DPU version 5.0.0.
> 
> Signed-off-by: Vinod Polimera <quic_vpolimer@...cinc.com>
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.c |  3 ++-
>  drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h | 12 +++++++-----
>  drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c    |  8 +++++++-
>  3 files changed, 16 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.c
> index 27f029f..0332cea 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.c
> @@ -77,7 +77,8 @@
>  
>  #define INTF_SC7180_MASK BIT(DPU_INTF_INPUT_CTRL) | BIT(DPU_INTF_TE)
>  
> -#define INTF_SC7280_MASK INTF_SC7180_MASK | BIT(DPU_DATA_HCTL_EN)
> +#define INTF_SC7280_MASK \
> +	(INTF_SC7180_MASK | BIT(DPU_DATA_HCTL_EN) | BIT(DPU_INTF_STATUS_SUPPORTED))
>  
>  #define IRQ_SDM845_MASK (BIT(MDP_SSPP_TOP0_INTR) | \
>  			 BIT(MDP_SSPP_TOP0_INTR2) | \
> 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 38aa38a..21ae3cf 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h
> @@ -203,17 +203,19 @@ enum {
>  
>  /**
>   * INTF sub-blocks
> - * @DPU_INTF_INPUT_CTRL         Supports the setting of pp block from which
> - *                              pixel data arrives to this INTF
> - * @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_INPUT_CTRL             Supports the setting of pp block from which
> + *                                  pixel data arrives to this INTF
> + * @DPU_INTF_TE                     INTF block has TE configuration support
> + * @DPU_DATA_HCTL_EN                Allows data to be transferred at different rate
> +				    than video timing

Use spaces instead of tabs.

> + * @DPU_INTF_STATUS_SUPPORTED       INTF block has INTF_STATUS register
>   * @DPU_INTF_MAX
>   */
>  enum {
>  	DPU_INTF_INPUT_CTRL = 0x1,
>  	DPU_INTF_TE,
>  	DPU_DATA_HCTL_EN,
> +	DPU_INTF_STATUS_SUPPORTED,
>  	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 7ce66bf..2394473 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
> @@ -62,6 +62,7 @@
>  #define   INTF_LINE_COUNT               0x0B0
>  
>  #define   INTF_MUX                      0x25C
> +#define   INTF_STATUS                   0x26C
>  
>  #define INTF_CFG_ACTIVE_H_EN	BIT(29)
>  #define INTF_CFG_ACTIVE_V_EN	BIT(30)
> @@ -297,8 +298,13 @@ static void dpu_hw_intf_get_status(
>  		struct intf_status *s)
>  {
>  	struct dpu_hw_blk_reg_map *c = &intf->hw;
> +	unsigned long cap = intf->cap->features;
> +
> +	if (cap & BIT(DPU_INTF_STATUS_SUPPORTED))
> +		s->is_en = BIT(0) & DPU_REG_READ(c, INTF_STATUS);

It is more clear to write `& BIT(0)` at the end.

- Marijn

> +	else
> +		s->is_en = DPU_REG_READ(c, INTF_TIMING_ENGINE_EN);
>  
> -	s->is_en = DPU_REG_READ(c, INTF_TIMING_ENGINE_EN);
>  	s->is_prog_fetch_en = !!(DPU_REG_READ(c, INTF_CONFIG) & BIT(31));
>  	if (s->is_en) {
>  		s->frame_count = DPU_REG_READ(c, INTF_FRAME_COUNT);
> -- 
> 2.7.4
>