linux-kernel - [PATCH 3/4] drm/msm/a6xx: Get HBB dynamically, if available

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Message-Id: <20250409-topic-smem_dramc-v1-3-94d505cd5593@oss.qualcomm.com>
Date: Wed, 09 Apr 2025 16:47:31 +0200
From: Konrad Dybcio <konradybcio@...nel.org>
To: Bjorn Andersson <andersson@...nel.org>, 
 Konrad Dybcio <konradybcio@...nel.org>, Kees Cook <kees@...nel.org>, 
 "Gustavo A. R. Silva" <gustavoars@...nel.org>, 
 Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>, 
 Abhinav Kumar <quic_abhinavk@...cinc.com>, 
 Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Dmitry Baryshkov <lumag@...nel.org>
Cc: Marijn Suijten <marijn.suijten@...ainline.org>, 
 linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org, 
 linux-hardening@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
 freedreno@...ts.freedesktop.org, 
 Konrad Dybcio <konrad.dybcio@....qualcomm.com>
Subject: [PATCH 3/4] drm/msm/a6xx: Get HBB dynamically, if available

From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>

The Highest Bank address Bit value can change based on memory type used.

Attempt to retrieve it dynamically, and fall back to a reasonable
default (the one used prior to this change) on error.

Signed-off-by: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
---
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index 06465bc2d0b4b128cddfcfcaf1fe4252632b6777..0cc397378c99db35315209d0265ad9223e8b55c7 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -13,6 +13,7 @@
 #include <linux/firmware/qcom/qcom_scm.h>
 #include <linux/pm_domain.h>
 #include <linux/soc/qcom/llcc-qcom.h>
+#include <linux/soc/qcom/smem.h>

 #define GPU_PAS_ID 13

@@ -669,17 +670,22 @@ static void a6xx_calc_ubwc_config(struct adreno_gpu *gpu)
 static void a6xx_set_ubwc_config(struct msm_gpu *gpu)
 {
 	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	u32 hbb = qcom_smem_dram_get_hbb();
+	u32 ubwc_mode = adreno_gpu->ubwc_config.ubwc_swizzle & 1;
+	u32 level2_swizzling_dis = !(adreno_gpu->ubwc_config.ubwc_swizzle & 2);
+	u32 hbb_hi, hbb_lo;
+
 	/*
 	 * We subtract 13 from the highest bank bit (13 is the minimum value
 	 * allowed by hw) and write the lowest two bits of the remaining value
 	 * as hbb_lo and the one above it as hbb_hi to the hardware.
 	 */
-	BUG_ON(adreno_gpu->ubwc_config.highest_bank_bit < 13);
-	u32 hbb = adreno_gpu->ubwc_config.highest_bank_bit - 13;
-	u32 hbb_hi = hbb >> 2;
-	u32 hbb_lo = hbb & 3;
-	u32 ubwc_mode = adreno_gpu->ubwc_config.ubwc_swizzle & 1;
-	u32 level2_swizzling_dis = !(adreno_gpu->ubwc_config.ubwc_swizzle & 2);
+	if (hbb < 0)
+		hbb = adreno_gpu->ubwc_config.highest_bank_bit;
+	hbb -= 13;
+	BUG_ON(hbb < 0);
+	hbb_hi = hbb >> 2;
+	hbb_lo = hbb & 3;

 	gpu_write(gpu, REG_A6XX_RB_NC_MODE_CNTL,
 		  level2_swizzling_dis << 12 |
@@ -2467,6 +2473,10 @@ struct msm_gpu *a6xx_gpu_init(struct drm_device *dev)
 	bool is_a7xx;
 	int ret;

+	/* We need data from SMEM to retrieve HBB in set_ubwc_config() */
+	if (!qcom_smem_is_available())
+		return ERR_PTR(-EPROBE_DEFER);
+
 	a6xx_gpu = kzalloc(sizeof(*a6xx_gpu), GFP_KERNEL);
 	if (!a6xx_gpu)
 		return ERR_PTR(-ENOMEM);

-- 
2.49.0