[PATCH 22/22] drm/amdgpu: workaround tonga HW bug in HQD programming sequence

[Andres Rodriguez]

Tonga based asics may experience hangs when an HQD's EOP parameters
are modified.

Workaround this HW issue by avoiding writes to these registers for
tonga asics.

Based on the following ROCm commit:
2a0fb8 - drm/amdgpu: Synchronize KFD HQD load protocol with CP scheduler

>From the ROCm git repository:
https://github.com/RadeonOpenCompute/ROCK-Kernel-Driver.git

CC: Jay Cornwall <Jay.Cornwall at amd.com>
Suggested-by: Felix Kuehling <Felix.Kuehling at amd.com>
Signed-off-by: Andres Rodriguez <andresx7 at gmail.com>
---
 drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
index 7e9d6f8..f7c68e4 100644
--- a/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
@@ -4938,7 +4938,21 @@ int gfx_v8_0_mqd_commit(struct amdgpu_device *adev, struct vi_mqd *mqd)
 	WREG32(mmCP_PQ_WPTR_POLL_CNTL, tmp);
 
 	/* program all HQD registers */
-	for (mqd_reg = mmCP_HQD_VMID; mqd_reg <= mmCP_HQD_ERROR; mqd_reg++)
+	for (mqd_reg = mmCP_HQD_VMID; mqd_reg <= mmCP_HQD_EOP_CONTROL; mqd_reg++)
+		WREG32(mqd_reg, mqd_data[mqd_reg - mmCP_MQD_BASE_ADDR]);
+
+	/* Tonga errata: EOP RPTR/WPTR should be left unmodified.
+	 * This is safe since EOP RPTR==WPTR for any inactive HQD
+	 * on ASICs that do not support context-save.
+	 * EOP writes/reads can start anywhere in the ring.
+	 */
+	if (adev->asic_type != CHIP_TONGA) {
+		WREG32(mmCP_HQD_EOP_RPTR, mqd->cp_hqd_eop_rptr);
+		WREG32(mmCP_HQD_EOP_WPTR, mqd->cp_hqd_eop_wptr);
+		WREG32(mmCP_HQD_EOP_WPTR_MEM, mqd->cp_hqd_eop_wptr_mem);
+	}
+
+	for (mqd_reg = mmCP_HQD_EOP_EVENTS; mqd_reg <= mmCP_HQD_ERROR; mqd_reg++)
 		WREG32(mqd_reg, mqd_data[mqd_reg - mmCP_MQD_BASE_ADDR]);
 
 	/* activate the HQD */
-- 
2.9.3