linux-kernel - Re: [PATCH 2/2] hwmon (occ): Retry for checksum failure

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Message-ID: <20220424171816.GA749761@roeck-us.net>
Date:   Sun, 24 Apr 2022 10:18:16 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Eddie James <eajames@...ux.ibm.com>
Cc:     linux-fsi@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        linux-hwmon@...r.kernel.org, jdelvare@...e.com, joel@....id.au,
        jk@...abs.org, alistair@...ple.id.au
Subject: Re: [PATCH 2/2] hwmon (occ): Retry for checksum failure

On Mon, Mar 21, 2022 at 10:31:12AM -0500, Eddie James wrote:
> Due to the OCC communication design with a shared SRAM area,
> checkum errors are expected due to corrupted buffer from OCC
> communications with other system components. Therefore, retry
> the command twice in the event of a checksum failure.
> 
> Signed-off-by: Eddie James <eajames@...ux.ibm.com>

I assume this will be applied together with patch 1 of the series.

Acked-by: Guenter Roeck <linux@...ck-us.net>

Guenter

> ---
>  drivers/hwmon/occ/p9_sbe.c | 28 ++++++++++++++++++----------
>  1 file changed, 18 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/hwmon/occ/p9_sbe.c b/drivers/hwmon/occ/p9_sbe.c
> index 49b13cc01073..7f4c3f979c54 100644
> --- a/drivers/hwmon/occ/p9_sbe.c
> +++ b/drivers/hwmon/occ/p9_sbe.c
> @@ -84,17 +84,25 @@ static int p9_sbe_occ_send_cmd(struct occ *occ, u8 *cmd, size_t len)
>  	struct p9_sbe_occ *ctx = to_p9_sbe_occ(occ);
>  	size_t resp_len = sizeof(*resp);
>  	int rc;
> -
> -	rc = fsi_occ_submit(ctx->sbe, cmd, len, resp, &resp_len);
> -	if (rc < 0) {
> -		if (resp_len) {
> -			if (p9_sbe_occ_save_ffdc(ctx, resp, resp_len))
> -				sysfs_notify(&occ->bus_dev->kobj, NULL,
> -					     bin_attr_ffdc.attr.name);
> +	int tries = 0;
> +
> +	do {
> +		rc = fsi_occ_submit(ctx->sbe, cmd, len, resp, &resp_len);
> +		if (rc < 0) {
> +			if (resp_len) {
> +				if (p9_sbe_occ_save_ffdc(ctx, resp, resp_len))
> +					sysfs_notify(&occ->bus_dev->kobj, NULL,
> +						     bin_attr_ffdc.attr.name);
> +
> +				return rc;
> +			} else if (rc != -EBADE) {
> +				return rc;
> +			}
> +			/* retry twice for checksum failures */
> +		} else {
> +			break;
>  		}
> -
> -		return rc;
> -	}
> +	} while (++tries < 3);
>  
>  	switch (resp->return_status) {
>  	case OCC_RESP_CMD_IN_PRG: