Re: [PATCH] drm/xe/slpc: Remove unnecessary force wakes

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Mon, Dec 16, 2024 at 11:41:19AM -0800, Vinay Belgaumkar wrote:
> FORCEWAKE_ALL is not needed when we are trying to read the cur_freq,
> we just need to wake up the GT domain. We also do not need a force wake
> to for a H2G query to obtain min frequency.
> 
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

> ---
>  drivers/gpu/drm/xe/xe_guc_pc.c | 26 +++++++-------------------
>  1 file changed, 7 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_guc_pc.c b/drivers/gpu/drm/xe/xe_guc_pc.c
> index e8b9faeaef64..5f9828ffc19c 100644
> --- a/drivers/gpu/drm/xe/xe_guc_pc.c
> +++ b/drivers/gpu/drm/xe/xe_guc_pc.c
> @@ -421,8 +421,8 @@ int xe_guc_pc_get_cur_freq(struct xe_guc_pc *pc, u32 *freq)
>  	 * GuC SLPC plays with cur freq request when GuCRC is enabled
>  	 * Block RC6 for a more reliable read.
>  	 */
> -	fw_ref = xe_force_wake_get(gt_to_fw(gt), XE_FORCEWAKE_ALL);
> -	if (!xe_force_wake_ref_has_domain(fw_ref, XE_FORCEWAKE_ALL)) {
> +	fw_ref = xe_force_wake_get(gt_to_fw(gt), XE_FW_GT);
> +	if (!xe_force_wake_ref_has_domain(fw_ref, XE_FW_GT)) {
>  		xe_force_wake_put(gt_to_fw(gt), fw_ref);
>  		return -ETIMEDOUT;
>  	}
> @@ -481,10 +481,10 @@ u32 xe_guc_pc_get_rpn_freq(struct xe_guc_pc *pc)
>   */
>  int xe_guc_pc_get_min_freq(struct xe_guc_pc *pc, u32 *freq)
>  {
> -	struct xe_gt *gt = pc_to_gt(pc);
> -	unsigned int fw_ref;
>  	int ret;
>  
> +	xe_device_assert_mem_access(pc_to_xe(pc));
> +
>  	mutex_lock(&pc->freq_lock);
>  	if (!pc->freq_ready) {
>  		/* Might be in the middle of a gt reset */
> @@ -492,24 +492,12 @@ int xe_guc_pc_get_min_freq(struct xe_guc_pc *pc, u32 *freq)
>  		goto out;
>  	}
>  
> -	/*
> -	 * GuC SLPC plays with min freq request when GuCRC is enabled
> -	 * Block RC6 for a more reliable read.
> -	 */
> -	fw_ref = xe_force_wake_get(gt_to_fw(gt), XE_FORCEWAKE_ALL);
> -	if (!xe_force_wake_ref_has_domain(fw_ref, XE_FORCEWAKE_ALL)) {
> -		ret = -ETIMEDOUT;
> -		goto fw;
> -	}
> -
>  	ret = pc_action_query_task_state(pc);
>  	if (ret)
> -		goto fw;
> +		goto out;
>  
>  	*freq = pc_get_min_freq(pc);
>  
> -fw:
> -	xe_force_wake_put(gt_to_fw(gt), fw_ref);
>  out:
>  	mutex_unlock(&pc->freq_lock);
>  	return ret;
> @@ -969,8 +957,8 @@ int xe_guc_pc_start(struct xe_guc_pc *pc)
>  
>  	xe_gt_assert(gt, xe_device_uc_enabled(xe));
>  
> -	fw_ref = xe_force_wake_get(gt_to_fw(gt), XE_FORCEWAKE_ALL);
> -	if (!xe_force_wake_ref_has_domain(fw_ref, XE_FORCEWAKE_ALL)) {
> +	fw_ref = xe_force_wake_get(gt_to_fw(gt), XE_FW_GT);
> +	if (!xe_force_wake_ref_has_domain(fw_ref, XE_FW_GT)) {
>  		xe_force_wake_put(gt_to_fw(gt), fw_ref);
>  		return -ETIMEDOUT;
>  	}
> -- 
> 2.38.1
>