drm/amdgpu: Make SDMA phase quantum configurable
Set a configurable SDMA phase quantum when enabling SDMA context
switching. The default value significantly reduces SDMA latency
in page table updates when user-mode SDMA queues have concurrent
activity, compared to the initial HW setting.
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Andres Rodriguez <andres.rodriguez@amd.com>
Reviewed-by: Shaoyun Liu <shaoyun.liu@amd.com>
Acked-by: Chunming Zhou <david1.zhou@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/amd/amdgpu/cik_sdma.c b/drivers/gpu/drm/amd/amdgpu/cik_sdma.c
index 4a9cea0..f508f4d 100644
--- a/drivers/gpu/drm/amd/amdgpu/cik_sdma.c
+++ b/drivers/gpu/drm/amd/amdgpu/cik_sdma.c
@@ -351,14 +351,44 @@ static void cik_sdma_rlc_stop(struct amdgpu_device *adev)
*/
static void cik_ctx_switch_enable(struct amdgpu_device *adev, bool enable)
{
- u32 f32_cntl;
+ u32 f32_cntl, phase_quantum = 0;
int i;
+ if (amdgpu_sdma_phase_quantum) {
+ unsigned value = amdgpu_sdma_phase_quantum;
+ unsigned unit = 0;
+
+ while (value > (SDMA0_PHASE0_QUANTUM__VALUE_MASK >>
+ SDMA0_PHASE0_QUANTUM__VALUE__SHIFT)) {
+ value = (value + 1) >> 1;
+ unit++;
+ }
+ if (unit > (SDMA0_PHASE0_QUANTUM__UNIT_MASK >>
+ SDMA0_PHASE0_QUANTUM__UNIT__SHIFT)) {
+ value = (SDMA0_PHASE0_QUANTUM__VALUE_MASK >>
+ SDMA0_PHASE0_QUANTUM__VALUE__SHIFT);
+ unit = (SDMA0_PHASE0_QUANTUM__UNIT_MASK >>
+ SDMA0_PHASE0_QUANTUM__UNIT__SHIFT);
+ WARN_ONCE(1,
+ "clamping sdma_phase_quantum to %uK clock cycles\n",
+ value << unit);
+ }
+ phase_quantum =
+ value << SDMA0_PHASE0_QUANTUM__VALUE__SHIFT |
+ unit << SDMA0_PHASE0_QUANTUM__UNIT__SHIFT;
+ }
+
for (i = 0; i < adev->sdma.num_instances; i++) {
f32_cntl = RREG32(mmSDMA0_CNTL + sdma_offsets[i]);
if (enable) {
f32_cntl = REG_SET_FIELD(f32_cntl, SDMA0_CNTL,
AUTO_CTXSW_ENABLE, 1);
+ if (amdgpu_sdma_phase_quantum) {
+ WREG32(mmSDMA0_PHASE0_QUANTUM + sdma_offsets[i],
+ phase_quantum);
+ WREG32(mmSDMA0_PHASE1_QUANTUM + sdma_offsets[i],
+ phase_quantum);
+ }
} else {
f32_cntl = REG_SET_FIELD(f32_cntl, SDMA0_CNTL,
AUTO_CTXSW_ENABLE, 0);