[PATCH 2/2] drm/xe/pf: Clamp maximum execution quantum to 100s

[Piotr Piórkowski]

Michal Wajdeczko <michal.wajdeczko at intel.com> wrote on pią [2024-kwi-19 14:35:43 +0200]:
> GuC is silently clamping values of the execution quantum and
> preemption timeout KLVs to 100s. Perform explicit clamping on the
> driver side as later there is no way to read back values used by
> the firmware and we shouldn't mislead the user about actual values
> being used when we print them in dmesg or debugfs.
> 
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
> ---
>  drivers/gpu/drm/xe/xe_gt_sriov_pf_config.c | 18 ++++++++++++------
>  1 file changed, 12 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_pf_config.c b/drivers/gpu/drm/xe/xe_gt_sriov_pf_config.c
> index 0f5614877770..82d402030b9e 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_config.c
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_config.c
> @@ -187,14 +187,20 @@ static int pf_push_vf_cfg_dbs(struct xe_gt *gt, unsigned int vfid, u32 begin, u3
>  	return pf_push_vf_cfg_klvs(gt, vfid, 2, klvs, ARRAY_SIZE(klvs));
>  }
>  
> -static int pf_push_vf_cfg_exec_quantum(struct xe_gt *gt, unsigned int vfid, u32 exec_quantum)
> +static int pf_push_vf_cfg_exec_quantum(struct xe_gt *gt, unsigned int vfid, u32 *exec_quantum)
>  {
> -	return pf_push_vf_cfg_u32(gt, vfid, GUC_KLV_VF_CFG_EXEC_QUANTUM_KEY, exec_quantum);
> +	/* GuC will silently clamp values exceeding max */
> +	*exec_quantum = min_t(u32, *exec_quantum, GUC_KLV_VF_CFG_EXEC_QUANTUM_MAX_VALUE);
> +
> +	return pf_push_vf_cfg_u32(gt, vfid, GUC_KLV_VF_CFG_EXEC_QUANTUM_KEY, *exec_quantum);
>  }
>  
> -static int pf_push_vf_cfg_preempt_timeout(struct xe_gt *gt, unsigned int vfid, u32 preempt_timeout)
> +static int pf_push_vf_cfg_preempt_timeout(struct xe_gt *gt, unsigned int vfid, u32 *preempt_timeout)
>  {
> -	return pf_push_vf_cfg_u32(gt, vfid, GUC_KLV_VF_CFG_PREEMPT_TIMEOUT_KEY, preempt_timeout);
> +	/* GuC will silently clamp values exceeding max */
> +	*preempt_timeout = min_t(u32, *preempt_timeout, GUC_KLV_VF_CFG_PREEMPT_TIMEOUT_MAX_VALUE);
> +
> +	return pf_push_vf_cfg_u32(gt, vfid, GUC_KLV_VF_CFG_PREEMPT_TIMEOUT_KEY, *preempt_timeout);
>  }
>  
>  static int pf_push_vf_cfg_lmem(struct xe_gt *gt, unsigned int vfid, u64 size)
> @@ -1604,7 +1610,7 @@ static int pf_provision_exec_quantum(struct xe_gt *gt, unsigned int vfid,
>  	struct xe_gt_sriov_config *config = pf_pick_vf_config(gt, vfid);
>  	int err;
>  
> -	err = pf_push_vf_cfg_exec_quantum(gt, vfid, exec_quantum);
> +	err = pf_push_vf_cfg_exec_quantum(gt, vfid, &exec_quantum);
>  	if (unlikely(err))
>  		return err;
>  
> @@ -1674,7 +1680,7 @@ static int pf_provision_preempt_timeout(struct xe_gt *gt, unsigned int vfid,
>  	struct xe_gt_sriov_config *config = pf_pick_vf_config(gt, vfid);
>  	int err;
>  
> -	err = pf_push_vf_cfg_preempt_timeout(gt, vfid, preempt_timeout);
> +	err = pf_push_vf_cfg_preempt_timeout(gt, vfid, &preempt_timeout);
>  	if (unlikely(err))
>  		return err;
>  


LGTM:
Reviewed-by: Piotr Piórkowski <piotr.piorkowski at intel.com>

> -- 
> 2.43.0
> 

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