linux-kernel - [PATCH v2 2/6] drm/msm/a6xx: Explain CP_PROTECT_CNTL writes in a6xx_set_cp

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Message-Id: <20230517-topic-a7xx_prep-v2-2-5b9daa2b2cf0@linaro.org>
Date:   Fri, 19 May 2023 15:29:07 +0200
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Rob Clark <robdclark@...il.com>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     Marijn Suijten <marijn.suijten@...ainline.org>,
        Jonathan Marek <jonathan@...ek.ca>,
        linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Konrad Dybcio <konrad.dybcio@...aro.org>
Subject: [PATCH v2 2/6] drm/msm/a6xx: Explain CP_PROTECT_CNTL writes in
 a6xx_set_cp_protect

We have the necessary information, so explain which bit does what.

Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
---
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index 9fb214f150dd..deed42675fe2 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -771,9 +771,10 @@ static void a6xx_set_cp_protect(struct msm_gpu *gpu)
 	}
 
 	/*
-	 * Enable access protection to privileged registers, fault on an access
-	 * protect violation and select the last span to protect from the start
-	 * address all the way to the end of the register address space
+	 * BIT(0) - Enable access protection to privileged registers
+	 * BIT(1) - Enable fault on an access protect violation
+	 * BIT(3) - Select the last span to protect from the start
+	 * 	    address all the way to the end of the register address space
 	 */
 	gpu_write(gpu, REG_A6XX_CP_PROTECT_CNTL, BIT(0) | BIT(1) | BIT(3));
 

-- 
2.40.1