[PATCH] drm/amdgpu: fix identifying prefix and postfix SET_Q_MODE packet

[Christian König]

Am 04.11.24 um 10:18 schrieb ZhenGuo Yin:
> [Why]
> In legacy mode(no MCBP support) shadow_va of prefix SET_Q_MODE
> packet is set to 0, matching the value used in the postfix
> SET_Q_MODE packet. A prefix SET_Q_MODE packet will be skipped
> unexpectedly when mixed running jobs with shadowing on and off.

In general it seems to be a good idea to use the VMID instead of the 
shadow_va here.

But mixing applications with and without shadow is *not* supported, so 
this patch here doesn't really have a justification.

Regards,
Christian.

>
> [How]
> Both shadow_va and vmid should be set to 0 in postfix SET_Q_MODE
> packet. Combined these two conditions together to identify the
> prefix and postfix SET_Q_MODE packet.
>
> Fixes: 8bc75586ea01 ("drm/amdgpu: workaround to avoid SET_Q_MODE packets v2")
> Signed-off-by: ZhenGuo Yin <zhenguo.yin at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c
> index 5aff8f72de9c..01b9dfe5b307 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c
> @@ -5862,6 +5862,7 @@ static void gfx_v11_0_ring_emit_gfx_shadow(struct amdgpu_ring *ring,
>   {
>   	struct amdgpu_device *adev = ring->adev;
>   	unsigned int offs, end;
> +	bool is_postfix = !shadow_va && !vmid;
>   
>   	if (!adev->gfx.cp_gfx_shadow || !ring->ring_obj)
>   		return;
> @@ -5886,7 +5887,7 @@ static void gfx_v11_0_ring_emit_gfx_shadow(struct amdgpu_ring *ring,
>   	 * the postfix SET_Q_MODE packet. This is changed below with a
>   	 * WRITE_DATA command when the postfix executed.
>   	 */
> -	amdgpu_ring_write(ring, shadow_va ? 1 : 0);
> +	amdgpu_ring_write(ring, is_postfix ? 0 : 1);
>   	amdgpu_ring_write(ring, 0);
>   
>   	if (ring->set_q_mode_offs) {
> @@ -5901,7 +5902,7 @@ static void gfx_v11_0_ring_emit_gfx_shadow(struct amdgpu_ring *ring,
>   	 * When the postfix SET_Q_MODE packet executes we need to make sure that the
>   	 * next prefix SET_Q_MODE packet executes as well.
>   	 */
> -	if (!shadow_va) {
> +	if (is_postfix) {
>   		uint64_t addr;
>   
>   		addr = amdgpu_bo_gpu_offset(ring->ring_obj);
> @@ -5928,7 +5929,7 @@ static void gfx_v11_0_ring_emit_gfx_shadow(struct amdgpu_ring *ring,
>   	if (ring->set_q_mode_offs)
>   		amdgpu_ring_patch_cond_exec(ring, end);
>   
> -	if (shadow_va) {
> +	if (!is_postfix) {
>   		uint64_t token = shadow_va ^ csa_va ^ gds_va ^ vmid;
>   
>   		/*