Re: [PATCH 5/5] cxl/mbox: Retry sending mbox command upon RETRY return_code

[Adam Manzanares <a.manzanares@samsung.com>]

On Thu, Mar 17, 2022 at 04:40:49PM -0700, Davidlohr Bueso wrote:
> As mentioned in CXL 2.0 specs: the hardware can set a Retry
> Required if the the command was not completed due to a
> temporary error. An optional single retry may resolve the
> issue. This is the only retry case as in general they are
> not recommended for commands that return an error.
> 
> Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
> ---
>  drivers/cxl/core/mbox.c | 23 ++++++++++++++---------
>  1 file changed, 14 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
> index fa9e7043f158..567987052b68 100644
> --- a/drivers/cxl/core/mbox.c
> +++ b/drivers/cxl/core/mbox.c
> @@ -160,20 +160,25 @@ int cxl_mbox_send_cmd(struct cxl_dev_state *cxlds, u16 opcode, void *in,

Can you update the documentation cxl_mbox_send_cmd that the function now 
retries commands if the RC indicates it should be done?

>  		.size_out = out_size,
>  		.payload_out = out,
>  	};
> -	int rc;
> +	int rc, retry = 1;
>  
>  	if (out_size > cxlds->payload_size)
>  		return -E2BIG;
>  
> -	/* acquire and releases the mbox_mutex */
> -	rc = cxlds->mbox_send(cxlds, &mbox_cmd);
> -	if (rc)
> -		return rc;
> +	do {
> +		/* acquire and releases the mbox_mutex */
> +		rc = cxlds->mbox_send(cxlds, &mbox_cmd);
> +		if (rc)
> +			return rc;
>  
> -	if (mbox_cmd.return_code != CXL_MBOX_CMD_RC_SUCCESS) {
> -		int err = cxl_mbox_cmd_rc2errno(&mbox_cmd);
> -		return -err;
> -	}
> +		if (mbox_cmd.return_code == CXL_MBOX_CMD_RC_SUCCESS)
> +			break;
> +
> +		if (mbox_cmd.return_code != CXL_MBOX_CMD_RC_RETRY || !retry) {
> +			int err = cxl_mbox_cmd_rc2errno(&mbox_cmd);
> +			return -err;
> +		}
> +	} while (retry--);
>  
>  	/*
>  	 * Variable sized commands can't be validated and so it's up to the
> 
> -- 
> 2.26.2
>

Other than the doc change for the cxl_mbox_send_cmd function.
LGTM

Reviewed by: Adam Manzanares <a.manzanares@samsung.com>