Re: [PATCH] drm/xe/guc: Return CTB response length

[Matthew Brost <matthew.brost@intel.com>]

On Thu, Jan 11, 2024 at 04:27:24PM +0100, Michal Wajdeczko wrote:
> Not all CTB responses from the GuC are fixed size and we need to
> pass response length to the caller, if there was a response_buffer.
> Easiest solution is to return it as positive value from all
> xe_guc_ct_send_recv() functions.  The CTB response length is always
> between 1 and 254 (ie. GUC_HXG_MSG_MIN_LEN and GUC_CTB_MAX_DWORDS
> - GUC_HXG_MSG_MIN_LEN).
> 
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
> Cc: Matthew Brost <matthew.brost@intel.com>

I has purposed a different usage of the return value [1].

Perhaps we just have response len as a pass by ref argument?

Matt

[1] https://patchwork.freedesktop.org/patch/541762/?series=119096&rev=1

> ---
>  drivers/gpu/drm/xe/xe_guc_ct.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_guc_ct.c b/drivers/gpu/drm/xe/xe_guc_ct.c
> index c29f095aa1b9..d490a4d42c01 100644
> --- a/drivers/gpu/drm/xe/xe_guc_ct.c
> +++ b/drivers/gpu/drm/xe/xe_guc_ct.c
> @@ -780,7 +780,7 @@ static int guc_ct_send_recv(struct xe_guc_ct *ct, const u32 *action, u32 len,
>  		ret = -EIO;
>  	}
>  
> -	return ret > 0 ? 0 : ret;
> +	return ret > 0 ? response_buffer ? g2h_fence.response_len : 0 : ret;
>  }
>  
>  int xe_guc_ct_send_recv(struct xe_guc_ct *ct, const u32 *action, u32 len,
> 
> base-commit: 79184e72263e91528195db01783148435c7e4fad
> -- 
> 2.25.1
>