Re: [PATCH 2/2] tpm: add sleep only for retry in i2c_nuvoton_write_status()

From	Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 2/2] tpm: add sleep only for retry in i2c_nuvoton_write_status()
Date	2017-03-17 20:10 +0100
Message-ID	<tm5qb-2HS-21@gated-at.bofh.it> (permalink)
References	<tjxLY-7Vp-17@gated-at.bofh.it> <tjxLY-7Vp-19@gated-at.bofh.it>
Organization	Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo

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On Fri, Mar 10, 2017 at 01:45:54PM -0500, Nayna Jain wrote:
> Currently, there is an unnecessary 1 msec delay added in
> i2c_nuvoton_write_status() for the successful case. This 
> function is called multiple times during send() and recv(),
> which implies adding multiple extra delays for every TPM
> operation.
> 
> This patch calls usleep_range() only if retry is to be done.
> 
> Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com>
> Cc: stable@vger.kernel.org (linux-4.8)
> Reviewed-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

I applied this too.

/Jarkko

> ---
>  drivers/char/tpm/tpm_i2c_nuvoton.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_i2c_nuvoton.c b/drivers/char/tpm/tpm_i2c_nuvoton.c
> index 0c98c42..c642877 100644
> --- a/drivers/char/tpm/tpm_i2c_nuvoton.c
> +++ b/drivers/char/tpm/tpm_i2c_nuvoton.c
> @@ -124,8 +124,9 @@ static s32 i2c_nuvoton_write_status(struct i2c_client *client, u8 data)
>  	/* this causes the current command to be aborted */
>  	for (i = 0, status = -1; i < TPM_I2C_RETRY_COUNT && status < 0; i++) {
>  		status = i2c_nuvoton_write_buf(client, TPM_STS, 1, &data);
> -		usleep_range(TPM_I2C_BUS_DELAY, TPM_I2C_BUS_DELAY
> -			     + TPM_I2C_DELAY_RANGE);
> +		if (status < 0)
> +			usleep_range(TPM_I2C_BUS_DELAY, TPM_I2C_BUS_DELAY
> +				     + TPM_I2C_DELAY_RANGE);
>  	}
>  	return status;
>  }
> -- 
> 2.9.3
> 
> --
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Re: [PATCH 2/2] tpm: add sleep only for retry in  i2c_nuvoton_write_status() Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-03-17 20:10 +0100

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