[PATCH 2/2] drm/radeon: use WAIT_REG_MEM special op for CP HDP flush

[Christian König]

Every time we actually tried this it just ended in users reporting CP hangs.

Christian.

Am 22.08.19 um 00:20 schrieb Alex Deucher:
> Flush via the ring works differently on CIK and requires a
> special sequence.
>
> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
> ---
>   drivers/gpu/drm/radeon/cik.c | 73 +++++++++++++++++++++++++++-----------------
>   1 file changed, 45 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/gpu/drm/radeon/cik.c b/drivers/gpu/drm/radeon/cik.c
> index 0847367..03dd075 100644
> --- a/drivers/gpu/drm/radeon/cik.c
> +++ b/drivers/gpu/drm/radeon/cik.c
> @@ -3485,6 +3485,48 @@ int cik_ring_test(struct radeon_device *rdev, struct radeon_ring *ring)
>   	return r;
>   }
>   
> +static void cik_gfx_hdp_flush(struct radeon_device *rdev,
> +			      int ridx)
> +{
> +	struct radeon_ring *ring = &rdev->ring[ridx];
> +	u32 ref_and_mask;
> +
> +	switch (ring->idx) {
> +	case CAYMAN_RING_TYPE_CP1_INDEX:
> +	case CAYMAN_RING_TYPE_CP2_INDEX:
> +		switch (ring->me) {
> +		case 0:
> +			ref_and_mask = CP2 << ring->pipe;
> +			break;
> +		case 1:
> +			ref_and_mask = CP6 << ring->pipe;
> +			break;
> +		default:
> +			return;
> +		}
> +		break;
> +	case RADEON_RING_TYPE_GFX_INDEX:
> +		ref_and_mask = CP0;
> +		break;
> +	default:
> +		return;
> +	}
> +
> +	radeon_ring_write(ring, PACKET3(PACKET3_SET_UCONFIG_REG, 1));
> +	radeon_ring_write(ring, ((CP_WAIT_REG_MEM_TIMEOUT -
> +				  PACKET3_SET_UCONFIG_REG_START) >> 2));
> +	radeon_ring_write(ring, 0xfff);
> +
> +	radeon_ring_write(ring, PACKET3(PACKET3_WAIT_REG_MEM, 5));
> +	radeon_ring_write(ring, (WAIT_REG_MEM_OPERATION(1) | /* special op */
> +				 WAIT_REG_MEM_FUNCTION(3))); /* == */
> +	radeon_ring_write(ring, GPU_HDP_FLUSH_REQ >> 2);
> +	radeon_ring_write(ring, GPU_HDP_FLUSH_DONE >> 2);
> +	radeon_ring_write(ring, ref_and_mask);
> +	radeon_ring_write(ring, ref_and_mask);
> +	radeon_ring_write(ring, 0xa); /* poll interval */
> +}
> +
>   /**
>    * cik_fence_gfx_ring_emit - emit a fence on the gfx ring
>    *
> @@ -3511,15 +3553,7 @@ void cik_fence_gfx_ring_emit(struct radeon_device *rdev,
>   	radeon_ring_write(ring, fence->seq);
>   	radeon_ring_write(ring, 0);
>   	/* HDP flush */
> -	/* We should be using the new WAIT_REG_MEM special op packet here
> -	 * but it causes the CP to hang
> -	 */
> -	radeon_ring_write(ring, PACKET3(PACKET3_WRITE_DATA, 3));
> -	radeon_ring_write(ring, (WRITE_DATA_ENGINE_SEL(0) |
> -				 WRITE_DATA_DST_SEL(0)));
> -	radeon_ring_write(ring, HDP_MEM_COHERENCY_FLUSH_CNTL >> 2);
> -	radeon_ring_write(ring, 0);
> -	radeon_ring_write(ring, 0);
> +	cik_gfx_hdp_flush(rdev, fence->ring);
>   }
>   
>   /**
> @@ -3549,15 +3583,7 @@ void cik_fence_compute_ring_emit(struct radeon_device *rdev,
>   	radeon_ring_write(ring, fence->seq);
>   	radeon_ring_write(ring, 0);
>   	/* HDP flush */
> -	/* We should be using the new WAIT_REG_MEM special op packet here
> -	 * but it causes the CP to hang
> -	 */
> -	radeon_ring_write(ring, PACKET3(PACKET3_WRITE_DATA, 3));
> -	radeon_ring_write(ring, (WRITE_DATA_ENGINE_SEL(0) |
> -				 WRITE_DATA_DST_SEL(0)));
> -	radeon_ring_write(ring, HDP_MEM_COHERENCY_FLUSH_CNTL >> 2);
> -	radeon_ring_write(ring, 0);
> -	radeon_ring_write(ring, 0);
> +	cik_gfx_hdp_flush(rdev, fence->ring);
>   }
>   
>   bool cik_semaphore_ring_emit(struct radeon_device *rdev,
> @@ -5369,16 +5395,7 @@ void cik_vm_flush(struct radeon_device *rdev, int ridx, struct radeon_vm *vm)
>   	radeon_ring_write(ring, VMID(0));
>   
>   	/* HDP flush */
> -	/* We should be using the WAIT_REG_MEM packet here like in
> -	 * cik_fence_ring_emit(), but it causes the CP to hang in this
> -	 * context...
> -	 */
> -	radeon_ring_write(ring, PACKET3(PACKET3_WRITE_DATA, 3));
> -	radeon_ring_write(ring, (WRITE_DATA_ENGINE_SEL(0) |
> -				 WRITE_DATA_DST_SEL(0)));
> -	radeon_ring_write(ring, HDP_MEM_COHERENCY_FLUSH_CNTL >> 2);
> -	radeon_ring_write(ring, 0);
> -	radeon_ring_write(ring, 0);
> +	cik_gfx_hdp_flush(rdev, ridx);
>   
>   	/* bits 0-15 are the VM contexts0-15 */
>   	radeon_ring_write(ring, PACKET3(PACKET3_WRITE_DATA, 3));