[PATCH 6.18 211/641] drm/msm/dpu: offset HBB values written to DPU by -13

Greg Kroah-Hartman
2026-02-25T01:45:52Z

6.18-stable review patch. If anyone has any objections, please let me know.

------------------

From: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>

[ Upstream commit 7ead14d4b9742b5ed244f35b999f0fe26dc23586 ]

As in all other places, the Highest Bank Bit value should be programmed
into the hardware with the offset of -13. Correct the value written
into the register to prevent unpredictable results.

Fixes: 227d4ce0b09e ("drm/msm: Offset MDSS HBB value by 13")
Tested-by: Val Packett <val@packett.cool> # x1e80100-dell-latitude-7455
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/699276/
Link: https://lore.kernel.org/r/20260119-msm-ubwc-fixes-v4-2-0987acc0427f@oss.qualcomm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/msm/disp/dpu1/dpu_hw_sspp.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_sspp.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_sspp.c
index 6f1fc790ad6d8..b66c4cb5760c9 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_sspp.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_sspp.c
@@ -270,30 +270,32 @@ static void dpu_hw_sspp_setup_format(struct dpu_sw_pipe *pipe,
((fmt->bpp - 1) << 9);

if (fmt->fetch_mode != MDP_FETCH_LINEAR) {
+ u32 hbb = ctx->ubwc->highest_bank_bit - 13;
+
if (MSM_FORMAT_IS_UBWC(fmt))
opmode |= MDSS_MDP_OP_BWC_EN;
src_format |= (fmt->fetch_mode & 3) << 30; /*FRAME_FORMAT */
DPU_REG_WRITE(c, SSPP_FETCH_CONFIG,
DPU_FETCH_CONFIG_RESET_VALUE |
- ctx->ubwc->highest_bank_bit << 18);
+ hbb << 18);
switch (ctx->ubwc->ubwc_enc_version) {
case UBWC_1_0:
fast_clear = fmt->alpha_enable ? BIT(31) : 0;
DPU_REG_WRITE(c, SSPP_UBWC_STATIC_CTRL,
fast_clear | (ctx->ubwc->ubwc_swizzle & 0x1) |
BIT(8) |
- (ctx->ubwc->highest_bank_bit << 4));
+ (hbb << 4));
break;
case UBWC_2_0:
fast_clear = fmt->alpha_enable ? BIT(31) : 0;
DPU_REG_WRITE(c, SSPP_UBWC_STATIC_CTRL,
fast_clear | (ctx->ubwc->ubwc_swizzle) |
- (ctx->ubwc->highest_bank_bit << 4));
+ (hbb << 4));
break;
case UBWC_3_0:
DPU_REG_WRITE(c, SSPP_UBWC_STATIC_CTRL,
BIT(30) | (ctx->ubwc->ubwc_swizzle) |
- (ctx->ubwc->highest_bank_bit << 4));
+ (hbb << 4));
break;
case UBWC_4_0:
DPU_REG_WRITE(c, SSPP_UBWC_STATIC_CTRL,
--
2.51.0