linux-kernel - Re: [PATCH v4 4/4] drm/msm/dpu: fix SSPP_UBWC_STATIC

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Message-ID: <35fababe-11ec-48a8-a6a1-d1aa1ab95dca@oss.qualcomm.com>
Date: Mon, 19 Jan 2026 13:24:58 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
        Rob Clark <robin.clark@....qualcomm.com>,
        Dmitry Baryshkov
 <lumag@...nel.org>,
        Abhinav Kumar <abhinav.kumar@...ux.dev>,
        Jessica Zhang <jesszhan0024@...il.com>, Sean Paul <sean@...rly.run>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        Konrad Dybcio <konradybcio@...nel.org>, Vinod Koul <vkoul@...nel.org>,
        Stephan Gerhold <stephan.gerhold@...aro.org>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Val Packett <val@...kett.cool>
Subject: Re: [PATCH v4 4/4] drm/msm/dpu: fix SSPP_UBWC_STATIC_CTRL programming
 on UBWC 5.x+

On 1/19/26 1:16 PM, Dmitry Baryshkov wrote:
> Code in dpu_hw_sspp_setup_format() doesn't handle UBWC versions bigger
> than 4.0. Replace switch-case with if-else checks, making sure that the
> register is initialized on UBWC 5.x (and later) hosts.
> 
> Fixes: c2577fc1740d ("drm/msm/dpu: Add support for SM8750")
> Tested-by: Val Packett <val@...kett.cool> # x1e80100-dell-latitude-7455
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
> ---

[...]

> +		if (ctx->ubwc->ubwc_enc_version == UBWC_1_0) {
>  			fast_clear = fmt->alpha_enable ? BIT(31) : 0;
> -			DPU_REG_WRITE(c, ubwc_ctrl_off,
> -					fast_clear | (ctx->ubwc->ubwc_swizzle & 0x1) |
> -					BIT(8) |
> -					(hbb << 4));
> -			break;
> -		case UBWC_2_0:
> +			ctrl_val = fast_clear | (ctx->ubwc->ubwc_swizzle & 0x1) |
> +				BIT(8) | (hbb << 4);
> +		} else if (ctx->ubwc->ubwc_enc_version == UBWC_2_0) {
>  			fast_clear = fmt->alpha_enable ? BIT(31) : 0;
> -			DPU_REG_WRITE(c, ubwc_ctrl_off,
> -					fast_clear | (ctx->ubwc->ubwc_swizzle) |
> -					(hbb << 4));
> -			break;
> -		case UBWC_3_0:
> -			DPU_REG_WRITE(c, ubwc_ctrl_off,
> -					BIT(30) | (ctx->ubwc->ubwc_swizzle) |
> -					(hbb << 4));
> -			break;
> -		case UBWC_4_0:
> -			DPU_REG_WRITE(c, ubwc_ctrl_off,
> -					MSM_FORMAT_IS_YUV(fmt) ? 0 : BIT(30));
> -			break;
> +			ctrl_val = fast_clear | ctx->ubwc->ubwc_swizzle | (hbb << 4);
> +		} else if (ctx->ubwc->ubwc_enc_version == UBWC_3_0) {
> +			ctrl_val = BIT(30) | (ctx->ubwc->ubwc_swizzle) | (hbb << 4);

This is pre-existing, but BIT(30) is not unconditional in SDE for v3

For this patch

Reviewed-by: Konrad Dybcio <konrad.dybcio@....qualcomm.com>

Konrad