Re: [PATCH] drm/xe: Grab mem_access when disabling C6 on skip_guc_pc platforms

[Matthew Auld <matthew.auld@intel.com>]

On 26/01/2024 22:06, Matt Roper wrote:
> If skip_guc_pc is set for a platform, C6 is disabled directly without
> acquiring a mem_access reference, triggering an assertion inside
> xe_gt_idle_disable_c6.
> 
> Fixes: 975e4a3795d4 ("drm/xe: Manually setup C6 when skip_guc_pc is set")
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Cc: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
> Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>

> ---
> Rodrigo has a pending series to kill off mem_access in general, but
> that's a large, complicated series that will probably take some time to
> land.  This quick fix is still useful in the meantime.
> 
>   drivers/gpu/drm/xe/xe_guc_pc.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_guc_pc.c b/drivers/gpu/drm/xe/xe_guc_pc.c
> index f71085228cb3..d91702592520 100644
> --- a/drivers/gpu/drm/xe/xe_guc_pc.c
> +++ b/drivers/gpu/drm/xe/xe_guc_pc.c
> @@ -963,7 +963,9 @@ void xe_guc_pc_fini(struct xe_guc_pc *pc)
>   	struct xe_device *xe = pc_to_xe(pc);
>   
>   	if (xe->info.skip_guc_pc) {
> +		xe_device_mem_access_get(xe);
>   		xe_gt_idle_disable_c6(pc_to_gt(pc));
> +		xe_device_mem_access_put(xe);
>   		return;
>   	}
>