linux-kernel - Re: [PATCH] drm/msm/dpu: fix/enable 6bpc dither with split-lm

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Date:   Sun, 19 Jul 2020 14:55:52 -0500
From:   Steev Klimaszewski <steev@...i.org>
To:     Rob Clark <robdclark@...il.com>, dri-devel@...ts.freedesktop.org
Cc:     Steev Klimaszewski <steev@...too.org>,
        Doug Anderson <dianders@...omium.org>,
        Rob Clark <robdclark@...omium.org>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Drew Davenport <ddavenport@...omium.org>,
        Kalyan Thota <kalyan_t@...eaurora.org>,
        Zheng Bin <zhengbin13@...wei.com>,
        Sam Ravnborg <sam@...nborg.org>,
        Stephen Boyd <swboyd@...omium.org>,
        "open list:DRM DRIVER FOR MSM ADRENO GPU" 
        <linux-arm-msm@...r.kernel.org>,
        "open list:DRM DRIVER FOR MSM ADRENO GPU" 
        <freedreno@...ts.freedesktop.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/msm/dpu: fix/enable 6bpc dither with split-lm

Hi,

On 7/15/20 5:19 PM, Rob Clark wrote:
> From: Rob Clark <robdclark@...omium.org>
>
> If split-lm is used (for ex, on sdm845), we can have multiple ping-
> pongs, but only a single phys encoder.  We need to configure dithering
> on each of them.
>
> Signed-off-by: Rob Clark <robdclark@...omium.org>
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c   | 22 ++++++++++---------
>  .../gpu/drm/msm/disp/dpu1/dpu_hw_pingpong.c   |  3 +--
>  2 files changed, 13 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> index 46df0ff75b85..9b98b63c77fb 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> @@ -212,14 +212,14 @@ static u32 dither_matrix[DITHER_MATRIX_SZ] = {
>  	15, 7, 13, 5, 3, 11, 1, 9, 12, 4, 14, 6, 0, 8, 2, 10
>  };
>  
> -static void _dpu_encoder_setup_dither(struct dpu_encoder_phys *phys)
> +static void _dpu_encoder_setup_dither(struct dpu_hw_pingpong *hw_pp, unsigned bpc)
>  {
>  	struct dpu_hw_dither_cfg dither_cfg = { 0 };
>  
> -	if (!phys->hw_pp || !phys->hw_pp->ops.setup_dither)
> +	if (!hw_pp->ops.setup_dither)
>  		return;
>  
> -	switch (phys->connector->display_info.bpc) {
> +	switch (bpc) {
>  	case 6:
>  		dither_cfg.c0_bitdepth = 6;
>  		dither_cfg.c1_bitdepth = 6;
> @@ -228,14 +228,14 @@ static void _dpu_encoder_setup_dither(struct dpu_encoder_phys *phys)
>  		dither_cfg.temporal_en = 0;
>  		break;
>  	default:
> -		phys->hw_pp->ops.setup_dither(phys->hw_pp, NULL);
> +		hw_pp->ops.setup_dither(hw_pp, NULL);
>  		return;
>  	}
>  
>  	memcpy(&dither_cfg.matrix, dither_matrix,
>  			sizeof(u32) * DITHER_MATRIX_SZ);
>  
> -	phys->hw_pp->ops.setup_dither(phys->hw_pp, &dither_cfg);
> +	hw_pp->ops.setup_dither(hw_pp, &dither_cfg);
>  }
>  
>  void dpu_encoder_helper_report_irq_timeout(struct dpu_encoder_phys *phys_enc,
> @@ -1132,11 +1132,13 @@ static void _dpu_encoder_virt_enable_helper(struct drm_encoder *drm_enc)
>  
>  	_dpu_encoder_update_vsync_source(dpu_enc, &dpu_enc->disp_info);
>  
> -	if (dpu_enc->disp_info.intf_type == DRM_MODE_ENCODER_DSI) {
> -		for (i = 0; i < dpu_enc->num_phys_encs; i++) {
> -			struct dpu_encoder_phys *phys = dpu_enc->phys_encs[i];
> -
> -			_dpu_encoder_setup_dither(phys);
> +	if (dpu_enc->disp_info.intf_type == DRM_MODE_ENCODER_DSI &&
> +			!WARN_ON(dpu_enc->num_phys_encs == 0)) {
> +		unsigned bpc = dpu_enc->phys_encs[0]->connector->display_info.bpc;
> +		for (i = 0; i < MAX_CHANNELS_PER_ENC; i++) {
> +			if (!dpu_enc->hw_pp[i])
> +				continue;
> +			_dpu_encoder_setup_dither(dpu_enc->hw_pp[i], bpc);
>  		}
>  	}
>  }
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_pingpong.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_pingpong.c
> index 7411ab6bf6af..bea4ab5c58c5 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_pingpong.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_pingpong.c
> @@ -231,8 +231,7 @@ static void _setup_pingpong_ops(struct dpu_hw_pingpong *c,
>  	c->ops.poll_timeout_wr_ptr = dpu_hw_pp_poll_timeout_wr_ptr;
>  	c->ops.get_line_count = dpu_hw_pp_get_line_count;
>  
> -	if (test_bit(DPU_PINGPONG_DITHER, &features) &&
> -		IS_SC7180_TARGET(c->hw.hwversion))
> +	if (test_bit(DPU_PINGPONG_DITHER, &features))
>  		c->ops.setup_dither = dpu_hw_pp_setup_dither;
>  };

Sorry for taking so long to get around to testing this.  I was able to
today, and it does reduce the banding to be less noticeable.

Tested-by: Steev Klimaszewski <steev@...i.org>

Thanks!

-- steev