[PATCH 6.6 022/105] drm/msm/a6xx: Fix PDC sleep sequence

Greg Kroah-Hartman
2025-10-21T19:53:16Z

From: Akhil P Oommen <akhilpo@oss.qualcomm.com>

[ Upstream commit f248d5d5159a88ded55329f0b1b463d0f4094228 ]

Since the PDC resides out of the GPU subsystem and cannot be reset in
case it enters bad state, utmost care must be taken to trigger the PDC
wake/sleep routines in the correct order.

The PDC wake sequence can be exercised only after a PDC sleep sequence.
Additionally, GMU firmware should initialize a few registers before the
KMD can trigger a PDC sleep sequence. So PDC sleep can't be done if the
GMU firmware has not initialized. Track these dependencies using a new
status variable and trigger PDC sleep/wake sequences appropriately.

Cc: stable@vger.kernel.org
Fixes: 4b565ca5a2cb ("drm/msm: Add A6XX device support")
Signed-off-by: Akhil P Oommen <akhilpo@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/673362/
Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>
[ omitted A7XX GPU logic and newer struct fields ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 34 ++++++++++++++++++++--------------
drivers/gpu/drm/msm/adreno/a6xx_gmu.h | 6 ++++++
2 files changed, 26 insertions(+), 14 deletions(-)

--- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
@@ -230,6 +230,8 @@ static int a6xx_gmu_start(struct a6xx_gm
if (ret)
DRM_DEV_ERROR(gmu->dev, "GMU firmware initialization timed out\n");

+ set_bit(GMU_STATUS_FW_START, &gmu->status);
+
return ret;
}

@@ -460,6 +462,9 @@ static int a6xx_rpmh_start(struct a6xx_g
int ret;
u32 val;

+ if (!test_and_clear_bit(GMU_STATUS_PDC_SLEEP, &gmu->status))
+ return 0;
+
gmu_write(gmu, REG_A6XX_GMU_RSCC_CONTROL_REQ, BIT(1));

ret = gmu_poll_timeout(gmu, REG_A6XX_GMU_RSCC_CONTROL_ACK, val,
@@ -487,6 +492,9 @@ static void a6xx_rpmh_stop(struct a6xx_g
int ret;
u32 val;

+ if (test_and_clear_bit(GMU_STATUS_FW_START, &gmu->status))
+ return;
+
gmu_write(gmu, REG_A6XX_GMU_RSCC_CONTROL_REQ, 1);

ret = gmu_poll_timeout_rscc(gmu, REG_A6XX_GPU_RSCC_RSC_STATUS0_DRV0,
@@ -495,6 +503,8 @@ static void a6xx_rpmh_stop(struct a6xx_g
DRM_DEV_ERROR(gmu->dev, "Unable to power off the GPU RSC\n");

gmu_write(gmu, REG_A6XX_GMU_RSCC_CONTROL_REQ, 0);
+
+ set_bit(GMU_STATUS_PDC_SLEEP, &gmu->status);
}

static inline void pdc_write(void __iomem *ptr, u32 offset, u32 value)
@@ -615,8 +625,6 @@ setup_pdc:
/* ensure no writes happen before the uCode is fully written */
wmb();

- a6xx_rpmh_stop(gmu);
-
err:
if (!IS_ERR_OR_NULL(pdcptr))
iounmap(pdcptr);
@@ -753,22 +761,18 @@ static int a6xx_gmu_fw_start(struct a6xx
gmu_write(gmu, REG_A6XX_GPU_GMU_CX_GMU_CX_FAL_INTF, 1);
}

- if (state == GMU_WARM_BOOT) {
- ret = a6xx_rpmh_start(gmu);
- if (ret)
- return ret;
- } else {
+ /* Turn on register retention */
+ gmu_write(gmu, REG_A6XX_GMU_GENERAL_7, 1);
+
+ ret = a6xx_rpmh_start(gmu);
+ if (ret)
+ return ret;
+
+ if (state == GMU_COLD_BOOT) {
if (WARN(!adreno_gpu->fw[ADRENO_FW_GMU],
"GMU firmware is not loaded\n"))
return -ENOENT;

- /* Turn on register retention */
- gmu_write(gmu, REG_A6XX_GMU_GENERAL_7, 1);
-
- ret = a6xx_rpmh_start(gmu);
- if (ret)
- return ret;
-
ret = a6xx_gmu_fw_load(gmu);
if (ret)
return ret;
@@ -907,6 +911,8 @@ static void a6xx_gmu_force_off(struct a6

/* Reset GPU core blocks */
a6xx_gpu_sw_reset(gpu, true);
+
+ a6xx_rpmh_stop(gmu);
}

static void a6xx_gmu_set_initial_freq(struct msm_gpu *gpu, struct a6xx_gmu *gmu)
--- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.h
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.h
@@ -96,6 +96,12 @@ struct a6xx_gmu {
/* For power domain callback */
struct notifier_block pd_nb;
struct completion pd_gate;
+
+/* To check if we can trigger sleep seq at PDC. Cleared in a6xx_rpmh_stop() */
+#define GMU_STATUS_FW_START 0
+/* To track if PDC sleep seq was done */
+#define GMU_STATUS_PDC_SLEEP 1
+ unsigned long status;
};

static inline u32 gmu_read(struct a6xx_gmu *gmu, u32 offset)