[PATCH v3 04/15] drm/msm/a6xx: Extend and explain UBWC config

[Konrad Dybcio <konrad.dybcio@linaro.org>]

Rename lower_bit to hbb_lo and explain what it signifies.
Add explanations (wherever possible to other tunables).

Sort the variable definition and assignment alphabetically.

Port setting min_access_length, ubwc_mode and hbb_hi from downstream.
Set default values for all of the tunables to zero, as they should be.

Values were validated against downstream and will be fixed up in
separate commits so as not to make this one even more messy.

A618 remains untouched (left at hw defaults) in this patch.

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
---
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 55 ++++++++++++++++++++++++++++-------
 1 file changed, 45 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index c5f5d0bb3fdc..bdae341e0a7c 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -786,39 +786,74 @@ static void a6xx_set_cp_protect(struct msm_gpu *gpu)
 static void a6xx_set_ubwc_config(struct msm_gpu *gpu)
 {
 	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
-	u32 lower_bit = 2;
+	/* Unknown, introduced with A640/680 */
 	u32 amsbc = 0;
+	/*
+	 * The Highest Bank Bit value represents the bit of the highest DDR bank.
+	 * We then subtract 13 from it (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. The default values (when HBB is
+	 * not specified) are 0, 0.
+	 */
+	u32 hbb_hi = 0;
+	u32 hbb_lo = 0;
+	/* Whether the minimum access length is 64 bits */
+	u32 min_acc_len = 0;
+	/* Unknown, introduced with A650 family, related to UBWC mode/ver 4 */
 	u32 rgb565_predicator = 0;
+	/* Unknown, introduced with A650 family */
 	u32 uavflagprd_inv = 0;
+	/* Entirely magic, per-GPU-gen value */
+	u32 ubwc_mode = 0;
 
 	/* a618 is using the hw default values */
 	if (adreno_is_a618(adreno_gpu))
 		return;
 
-	if (adreno_is_a640_family(adreno_gpu))
+	if (adreno_is_a619(adreno_gpu)) {
+		/* HBB = 14 */
+		hbb_lo = 1;
+	}
+
+	if (adreno_is_a630(adreno_gpu)) {
+		/* HBB = 15 */
+		hbb_lo = 2;
+	}
+
+	if (adreno_is_a640_family(adreno_gpu)) {
 		amsbc = 1;
+		/* HBB = 15 */
+		hbb_lo = 2;
+	}
 
 	if (adreno_is_a650(adreno_gpu) || adreno_is_a660(adreno_gpu)) {
-		/* TODO: get ddr type from bootloader and use 2 for LPDDR4 */
-		lower_bit = 3;
 		amsbc = 1;
+		/* TODO: get ddr type from bootloader and use 2 for LPDDR4 */
+		/* HBB = 16 */
+		hbb_lo = 3;
 		rgb565_predicator = 1;
 		uavflagprd_inv = 2;
 	}
 
 	if (adreno_is_7c3(adreno_gpu)) {
-		lower_bit = 1;
 		amsbc = 1;
+		/* HBB is unset in downstream DTS, defaulting to 0 */
 		rgb565_predicator = 1;
 		uavflagprd_inv = 2;
 	}
 
 	gpu_write(gpu, REG_A6XX_RB_NC_MODE_CNTL,
-		rgb565_predicator << 11 | amsbc << 4 | lower_bit << 1);
-	gpu_write(gpu, REG_A6XX_TPL1_NC_MODE_CNTL, lower_bit << 1);
-	gpu_write(gpu, REG_A6XX_SP_NC_MODE_CNTL,
-		uavflagprd_inv << 4 | lower_bit << 1);
-	gpu_write(gpu, REG_A6XX_UCHE_MODE_CNTL, lower_bit << 21);
+		  rgb565_predicator << 11 | hbb_hi << 10 | amsbc << 4 |
+		  min_acc_len << 3 | hbb_lo << 1 | ubwc_mode);
+
+	gpu_write(gpu, REG_A6XX_TPL1_NC_MODE_CNTL, hbb_hi << 4 |
+		  min_acc_len << 3 | hbb_lo << 1 | ubwc_mode);
+
+	gpu_write(gpu, REG_A6XX_SP_NC_MODE_CNTL, hbb_hi << 10 |
+		  uavflagprd_inv << 4 | min_acc_len << 3 |
+		  hbb_lo << 1 | ubwc_mode);
+
+	gpu_write(gpu, REG_A6XX_UCHE_MODE_CNTL, min_acc_len << 23 | hbb_lo << 21);
 }
 
 static int a6xx_cp_init(struct msm_gpu *gpu)

-- 
2.39.2