Re: [PATCH] drm/amdkfd: Enable SDMA IB processing

[Mukul Joshi <mukul.joshi@amd.com>]

On 10/19/2026 1:58 PM, Yongqiang Sun wrote:
> SDMA MQDs leave IB_ENABLE clear,
> causing INDIRECT packets to be ignored.
>
> Set IB_ENABLE while retaining SWITCH_INSIDE_IB.

This is not entirely true. We are enabling SWITCH_INSIDE_IB for GFX 10
and GFX 11 in the patch.

Maybe you can update the commit heading + description as:

"drm/amdkfd: Enable IB execution for user-mode SDMA queues

update_mqd_sdma() never sets IB_ENABLE in the SDMA queue IB_CNTL,
so INDIRECT packets submitted on user-mode SDMA queues are not executed.

Set IB_ENABLE on all MQD versions. On gfx10 and gfx11, also set
SWITCH_INSIDE_IB, which was previously only set on gfx9 and gfx12,
so that a long-running IB can be preempted."

With that fixed, this patch is:

Reviewed-by: Mukul Joshi <mukul.joshi@amd.com>


>
> Signed-off-by: Yongqiang Sun <Yongqiang.Sun@amd.com>
> ---
>  drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v10.c   |  7 +++++++
>  drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v11.c   |  7 +++++++
>  drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v12.c   | 11 ++++++-----
>  drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v12_1.c | 11 ++++++-----
>  drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v9.c    |  8 +++++---
>  5 files changed, 31 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v10.c b/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v10.c
> index 4f8a8a1a6186..25f5a2cf02ff 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v10.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v10.c
> @@ -396,6 +396,13 @@ static void update_mqd_sdma(struct mqd_manager *mm, void *mqd,
>  	m->sdma_queue_id = q->sdma_queue_id;
>  	m->sdmax_rlcx_dummy_reg = SDMA_RLC_DUMMY_DEFAULT;
>  
> +	/* Enable IB execution; allow context switch inside an IB so one
> +	 * queue cannot starve the engine.
> +	 */
> +	m->sdmax_rlcx_ib_cntl |=
> +		SDMA0_RLC0_IB_CNTL__IB_ENABLE_MASK |
> +		SDMA0_RLC0_IB_CNTL__SWITCH_INSIDE_IB_MASK;
> +
>  	q->is_active = QUEUE_IS_ACTIVE(*q);
>  }
>  
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v11.c b/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v11.c
> index bf015dc5b868..a1eecdf63b0c 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v11.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v11.c
> @@ -478,6 +478,13 @@ static void update_mqd_sdma(struct mqd_manager *mm, void *mqd,
>  	m->sdma_queue_id = q->sdma_queue_id;
>  	m->sdmax_rlcx_dummy_reg = SDMA_RLC_DUMMY_DEFAULT;
>  
> +	/* Enable IB execution; allow context switch inside an IB so one
> +	 * queue cannot starve the engine.
> +	 */
> +	m->sdmax_rlcx_ib_cntl |=
> +		SDMA0_QUEUE0_IB_CNTL__IB_ENABLE_MASK |
> +		SDMA0_QUEUE0_IB_CNTL__SWITCH_INSIDE_IB_MASK;
> +
>  	q->is_active = QUEUE_IS_ACTIVE(*q);
>  }
>  
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v12.c b/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v12.c
> index 6ea09b031caf..e0574fa325c4 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v12.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v12.c
> @@ -353,11 +353,12 @@ static void update_mqd_sdma(struct mqd_manager *mm, void *mqd,
>  
>  	m->sdmax_rlcx_dummy_reg = SDMA_RLC_DUMMY_DEFAULT;
>  
> -	/* Allow context switch so we don't cross-process starve with a massive
> -	* command buffer of long-running SDMA commands
> -	* sdmax_rlcx_ib_cntl represent SDMA_QUEUE0_IB_CNTL register
> -	*/
> -	m->sdmax_rlcx_ib_cntl |= SDMA0_QUEUE0_IB_CNTL__SWITCH_INSIDE_IB_MASK;
> +	/* Enable IB execution; allow context switch inside an IB so one
> +	 * queue cannot starve the engine.
> +	 */
> +	m->sdmax_rlcx_ib_cntl |=
> +		SDMA0_QUEUE0_IB_CNTL__IB_ENABLE_MASK |
> +		SDMA0_QUEUE0_IB_CNTL__SWITCH_INSIDE_IB_MASK;
>  
>  	q->is_active = QUEUE_IS_ACTIVE(*q);
>  }
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v12_1.c b/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v12_1.c
> index 2bbf5e63f615..04e1575dfe76 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v12_1.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v12_1.c
> @@ -457,11 +457,12 @@ static void update_mqd_sdma(struct mqd_manager *mm, void *mqd,
>  
>  	m->sdmax_queuen_dummy_reg1 = 1;
>  
> -	/* Allow context switch so we don't cross-process starve with a massive
> -	* command buffer of long-running SDMA commands
> -	* sdmax_queuen_ib_cntl represent SDMA_QUEUE0_IB_CNTL register
> -	*/
> -	m->sdmax_queuen_ib_cntl |= SDMA0_SDMA_QUEUE0_IB_CNTL__SWITCH_INSIDE_IB_MASK;
> +	/* Enable IB execution; allow context switch inside an IB so one
> +	 * queue cannot starve the engine.
> +	 */
> +	m->sdmax_queuen_ib_cntl |=
> +		SDMA0_SDMA_QUEUE0_IB_CNTL__IB_ENABLE_MASK |
> +		SDMA0_SDMA_QUEUE0_IB_CNTL__SWITCH_INSIDE_IB_MASK;
>  
>  	q->is_active = QUEUE_IS_ACTIVE(*q);
>  }
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v9.c b/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v9.c
> index 6e6bc1ec0b64..80df86f7c4d5 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v9.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v9.c
> @@ -569,10 +569,12 @@ static void update_mqd_sdma(struct mqd_manager *mm, void *mqd,
>  	m->sdma_engine_id = q->sdma_engine_id;
>  	m->sdma_queue_id = q->sdma_queue_id;
>  	m->sdmax_rlcx_dummy_reg = SDMA_RLC_DUMMY_DEFAULT;
> -	/* Allow context switch so we don't cross-process starve with a massive
> -	 * command buffer of long-running SDMA commands
> +	/* Enable IB execution; allow context switch inside an IB so one
> +	 * queue cannot starve the engine.
>  	 */
> -	m->sdmax_rlcx_ib_cntl |= SDMA0_GFX_IB_CNTL__SWITCH_INSIDE_IB_MASK;
> +	m->sdmax_rlcx_ib_cntl |=
> +		SDMA0_GFX_IB_CNTL__IB_ENABLE_MASK |
> +		SDMA0_GFX_IB_CNTL__SWITCH_INSIDE_IB_MASK;
>  
>  	q->is_active = QUEUE_IS_ACTIVE(*q);
>  }