[PATCH] dmaengine: qcom: gpi: Fix SE ID and SE Protocol fields widths in SCRATCH_0
From: Chandana Kishori Chiluveru
Date: Mon Jul 20 2026 - 12:32:30 EST
GPII_n_CH_k_SCRATCH_0_SEID is currently defined as GENMASK(2, 0), only
3 bits wide. Serial engine indices >= 8 get silently truncated by
FIELD_PREP()/u32_encode_bits() when written into the scratch register,
causing the GPI channel to bind to the wrong serial engine. The
channel allocate command still succeeds (it doesn't require the
target SE to respond), but the subsequent channel start command times
out waiting for hardware to complete the handoff to the (incorrectly
bound) SE, and gpi_send_cmd() returns -EIO leading to GSI usecase failures
for SE8 and SE9 serial engines.
Older documentation, such as the SDM845 hardware programming guide,
describes the SE ID field as bits [2:0]. More recent QUP hardware
documentation defines the field as bits [3:0]. Use the wider definition
to match current hardware documentation while remaining compatible with
existing platforms and enabling serial engine IDs greater than 7.
Also update the SE Protocol field definition to match the documented
register layout and keep both fields correctly packed.
Fixes: 5d0c3533a19f ("dmaengine: qcom: Add GPI dma driver")
Signed-off-by: Chandana Kishori Chiluveru <chandana.chiluveru@xxxxxxxxxxxxxxxx>
---
drivers/dma/qcom/gpi.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/dma/qcom/gpi.c b/drivers/dma/qcom/gpi.c
index a5055a6273af..8f09eaf4e714 100644
--- a/drivers/dma/qcom/gpi.c
+++ b/drivers/dma/qcom/gpi.c
@@ -207,8 +207,8 @@ enum CNTXT_OFFS {
/* Scratch registers */
#define GPII_n_CH_k_SCRATCH_0_OFFS(n, k) (0x20060 + (0x4000 * (n)) + (0x80 * (k)))
-#define GPII_n_CH_k_SCRATCH_0_SEID GENMASK(2, 0)
-#define GPII_n_CH_k_SCRATCH_0_PROTO GENMASK(7, 4)
+#define GPII_n_CH_k_SCRATCH_0_SEID GENMASK(3, 0)
+#define GPII_n_CH_k_SCRATCH_0_PROTO GENMASK(6, 4)
#define GPII_n_CH_k_SCRATCH_0_PAIR GENMASK(20, 16)
#define GPII_n_CH_k_SCRATCH_0(pair, proto, seid) \
(FIELD_PREP(GPII_n_CH_k_SCRATCH_0_PAIR, pair) | \
---
base-commit: 34cf6dafc47441dfb6b356a095b89c3585a93714
change-id: 20260710-fix_se_id_and_se_protocol_fields-d7f0fe616596
Best regards,
--
Chandana Kishori Chiluveru <chandana.chiluveru@xxxxxxxxxxxxxxxx>