Re: [PATCH v3 2/2] drm/xe: make change ccs_mode a synchronous action

[Nirmoy Das <nirmoy.das@linux.intel.com>]

On 12/11/2024 12:17 PM, Maciej Patelczyk wrote:
> If ccs_mode is being modified via
>    /sys/class/drm/cardX/device/tileY/gtY/ccs_mode
> the asynchronous reset is triggered and the write returns immediately.
>
> With that some test receive false information about number of CCS engines
> or even fail if they proceed without delay after changing the ccs_mode.
>
> Changing the ccs_mode change from async to sync to prevent failures in
> tests.

This sounds like a bug so I think this should have Fixes

Fixes: f3bc5bb4d53d ("drm/xe: Allow userspace to configure CCS mode")
Cc: <stable@vger.kernel.org> # v6.8+

> Signed-off-by: Maciej Patelczyk <maciej.patelczyk@intel.com>
> Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_gt_ccs_mode.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_gt_ccs_mode.c b/drivers/gpu/drm/xe/xe_gt_ccs_mode.c
> index b6adfb9f2030..50fffc9ebf62 100644
> --- a/drivers/gpu/drm/xe/xe_gt_ccs_mode.c
> +++ b/drivers/gpu/drm/xe/xe_gt_ccs_mode.c
> @@ -150,7 +150,7 @@ ccs_mode_store(struct device *kdev, struct device_attribute *attr,
>  		xe_gt_info(gt, "Setting compute mode to %d\n", num_engines);
>  		gt->ccs_mode = num_engines;
>  		xe_gt_record_user_engines(gt);
> -		xe_gt_reset_async(gt);
> +		xe_gt_reset(gt);
>  	}
>  
>  	mutex_unlock(&xe->drm.filelist_mutex);