Re: [PATCH v2 4/4] tpm_tis: Resend command to recover from data transfer errors

[Jarkko Sakkinen]

On Mon Jun 5, 2023 at 8:59 PM EEST, Alexander Steffen wrote:
> Similar to the transmission of TPM responses, also the transmission of TPM
> commands may become corrupted. Instead of aborting when detecting such
> issues, try resending the command again.
>
> Signed-off-by: Alexander Steffen <Alexander.Steffen@xxxxxxxxxxxx>
> ---
>  drivers/char/tpm/tpm_tis_core.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index a08768e55803..47073cc79b51 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -535,10 +535,18 @@ static int tpm_tis_send_main(struct tpm_chip *chip, const u8 *buf, size_t len)
>  	int rc;
>  	u32 ordinal;
>  	unsigned long dur;
> +	unsigned int try;
>  
> -	rc = tpm_tis_send_data(chip, buf, len);
> -	if (rc < 0)
> -		return rc;
> +	for (try = 0; try < TPM_RETRY; try++) {
> +		rc = tpm_tis_send_data(chip, buf, len);
> +		if (rc >= 0) {
> +			/* Data transfer done successfully */
> +			break;
> +		} else if (rc != -EIO) {
> +			/* Data transfer failed, not recoverable */
> +			return rc;
> +		}

Remove curly braces from the two statements above.

> +	}
>  
>  	/* go and do it */
>  	rc = tpm_tis_write8(priv, TPM_STS(priv->locality), TPM_STS_GO);
> -- 
> 2.34.1


BR, Jarkko