[PATCH v4 7/8] drm/amdgpu/sdma7_1: honor mqd_prop modify flag in init_mqd

[Jesse Zhang <Jesse.Zhang@amd.com>]

On a queue MODIFY (prop->modify) sdma7_1 init_mqd keeps the ring rptr/wptr
that firmware context-saved into the MQD, so a re-enabled queue resumes
at the first un-consumed packet. It also forces IB_ENABLE back on, since
ib_cntl reads back IB_ENABLE=0 on a stopped queue.

v3: consume the mqd_prop modify flag inside init_mqd instead of adding a
    separate sdma7_1 update_mqd callback, per review.
v4: also keep the context-saved wptr instead of programming a user_wptr,
    per review.

Signed-off-by: Jesse Zhang <Jesse.Zhang@amd.com>
Suggested-by: Alexander Deucher <Alexander.Deucher@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/sdma_v7_1.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/sdma_v7_1.c b/drivers/gpu/drm/amd/amdgpu/sdma_v7_1.c
index e9a3bcfd7775..0af11841b727 100644
--- a/drivers/gpu/drm/amd/amdgpu/sdma_v7_1.c
+++ b/drivers/gpu/drm/amd/amdgpu/sdma_v7_1.c
@@ -886,6 +886,14 @@ static int sdma_v7_1_mqd_init(struct amdgpu_device *adev, void *mqd,
 	m->sdmax_rlcx_csa_addr_lo = lower_32_bits(prop->csa_addr);
 	m->sdmax_rlcx_csa_addr_hi = upper_32_bits(prop->csa_addr);
 
+	if (prop->modify) {
+		/*
+		 * MODIFY keeps the firmware-saved rptr/wptr (left untouched above);
+		 * ib_cntl read back IB_ENABLE=0 on the stopped queue, so force it on.
+		 */
+		m->sdmax_rlcx_ib_cntl |= SDMA0_SDMA_QUEUE0_IB_CNTL__IB_ENABLE_MASK;
+	}
+
 	return 0;
 }
 
-- 
2.49.0