drm/amd/pm: zero unused SMU argument registers

SMU messages may use fewer arguments than the available argument registers,
the previous code only wrote used registers and left the rest unchanged,
so stale values from a prior message could persist.

Write all argument registers for each message and zero the unused tail
to keep command arguments deterministic and avoid unintended carry-over.

Signed-off-by: Yang Wang <kevinyang.wang@amd.com>
Reviewed-by: Asad Kamal <asad.kamal@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit e03b635f61f77ebd5107ef82f48e3221cb695856)

diff --git a/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c b/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c
index 90c7127beabffc46dbefc3c80ad4db01b44e15a4..fe97fda8bfe93e2fbe987ebecaba40e35c92ceab 100644 (file)
--- a/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c
+++ b/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c
@@ -272,11 +272,15 @@ static void __smu_msg_v1_send(struct smu_msg_ctl *ctl, u16 index,
 {
        struct amdgpu_device *adev = ctl->smu->adev;
        struct smu_msg_config *cfg = &ctl->config;
+       u32 arg;
        int i;
 
        WREG32(cfg->resp_reg, 0);
-       for (i = 0; i < args->num_args; i++)
-               WREG32(cfg->arg_regs[i], args->args[i]);
+       for (i = 0; i < cfg->num_arg_regs; i++) {
+               /* NOTE: Clear unused argument registers to avoid stale values. */
+               arg = i < args->num_args ? args->args[i] : 0;
+               WREG32(cfg->arg_regs[i], arg);
+       }
        WREG32(cfg->msg_reg, index);
 }