[PATCH 1/2] drm/amdgpu: Add HDP flush to VCN v4.0.3

[Christian König]

Am 05.03.24 um 07:40 schrieb Lijo Lazar:
> VCN 4.0.3 cannot trigger HDP flush with RRMT enabled. Instead, trigger
> HDP flush from host side before ringing doorbell.

Well that won't work like that.

The HDP flush is supposed to be emitted into the ring buffer of the 
engine. If you just "emulate" it by a register write than that write 
comes at the wrong time.

This code here is seriously broken.

Regards,
Christian.

>
> Signed-off-by: Lijo Lazar <lijo.lazar at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/vcn_v4_0_3.c | 25 +++++++++++++++++++++++++
>   1 file changed, 25 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/vcn_v4_0_3.c b/drivers/gpu/drm/amd/amdgpu/vcn_v4_0_3.c
> index 810bbfccd6f2..7b5ad13b618e 100644
> --- a/drivers/gpu/drm/amd/amdgpu/vcn_v4_0_3.c
> +++ b/drivers/gpu/drm/amd/amdgpu/vcn_v4_0_3.c
> @@ -36,6 +36,7 @@
>   #include "vcn/vcn_4_0_3_offset.h"
>   #include "vcn/vcn_4_0_3_sh_mask.h"
>   #include "ivsrcid/vcn/irqsrcs_vcn_4_0.h"
> +#include <uapi/linux/kfd_ioctl.h>
>   
>   #define mmUVD_DPG_LMA_CTL		regUVD_DPG_LMA_CTL
>   #define mmUVD_DPG_LMA_CTL_BASE_IDX	regUVD_DPG_LMA_CTL_BASE_IDX
> @@ -1380,6 +1381,26 @@ static uint64_t vcn_v4_0_3_unified_ring_get_wptr(struct amdgpu_ring *ring)
>   				    regUVD_RB_WPTR);
>   }
>   
> +static void vcn_v4_0_3_ring_emit_hdp_flush(struct amdgpu_ring *ring)
> +{
> +	/* VCN engine access for HDP flush doesn't work when RRMT is enabled.
> +	 * This is a workaround to avoid any HDP flush through VCN ring. Instead
> +	 * HDP flush will be done by driver while submitting doorbell.
> +	 */
> +}
> +
> +static void vcn_v4_0_3_flush_hdp(struct amdgpu_ring *ring)
> +{
> +	struct amdgpu_device *adev = ring->adev;
> +
> +#ifdef CONFIG_X86_64
> +	if ((adev->flags & AMD_IS_APU) && !amdgpu_passthrough(adev))
> +		return;
> +#endif
> +	if (ring->wptr)
> +		WREG32_NO_KIQ((adev->rmmio_remap.reg_offset + KFD_MMIO_REMAP_HDP_MEM_FLUSH_CNTL) >> 2, 0);
> +}
> +
>   /**
>    * vcn_v4_0_3_unified_ring_set_wptr - set enc write pointer
>    *
> @@ -1394,6 +1415,9 @@ static void vcn_v4_0_3_unified_ring_set_wptr(struct amdgpu_ring *ring)
>   	if (ring != &adev->vcn.inst[ring->me].ring_enc[0])
>   		DRM_ERROR("wrong ring id is identified in %s", __func__);
>   
> +	/* Flush HDP before ringing doorbell */
> +	vcn_v4_0_3_flush_hdp(ring);
> +
>   	if (ring->use_doorbell) {
>   		*ring->wptr_cpu_addr = lower_32_bits(ring->wptr);
>   		WDOORBELL32(ring->doorbell_index, lower_32_bits(ring->wptr));
> @@ -1420,6 +1444,7 @@ static const struct amdgpu_ring_funcs vcn_v4_0_3_unified_ring_vm_funcs = {
>   	.emit_ib = vcn_v2_0_enc_ring_emit_ib,
>   	.emit_fence = vcn_v2_0_enc_ring_emit_fence,
>   	.emit_vm_flush = vcn_v2_0_enc_ring_emit_vm_flush,
> +	.emit_hdp_flush = vcn_v4_0_3_ring_emit_hdp_flush,
>   	.test_ring = amdgpu_vcn_enc_ring_test_ring,
>   	.test_ib = amdgpu_vcn_unified_ring_test_ib,
>   	.insert_nop = amdgpu_ring_insert_nop,