[tpmdd-devel,v3] tpm: Apply a sane minimum adapterlimit value for retransmission.

Submitted by Enric Balletbo i Serra on March 28, 2017, 3:29 p.m.

Details

Message ID 20170328152938.14539-1-enric.balletbo@collabora.com
State New
Headers show

Commit Message

Enric Balletbo i Serra March 28, 2017, 3:29 p.m.
From: Bryan Freed <bfreed@chromium.org>

When the I2C Infineon part is attached to an I2C adapter that imposes
a size limitation, large requests will fail with -EOPNOTSUPP. Retry
them with a sane minimum size without re-issuing the 0x05 command
as this appears to occasionally put the TPM in a bad state.

Signed-off-by: Bryan Freed <bfreed@chromium.org>
[rework the patch to adapt to the feedback received]
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
---
This is a reworked version of the original patch based on the
suggestion made by Wolfram Sang to simply fall back to a sane minimum
when the maximum fails.

Changes since v2:
 - Do not remove faster transfers when chip is SLB9645 (Peter Huewe)
 - Remember the adapterlimit length once it fails to not generate extra
   i2c core messages (suggested by Andrew Lunn)
Changes since v1:
 - Check the correct return value (-EOPNOTSUPP instead of -EINVAL)
 - Fall back len to I2C_SMBUS_BLOCK_MAX if fails.

 drivers/char/tpm/tpm_i2c_infineon.c | 76 +++++++++++++++++++++++++++----------
 1 file changed, 56 insertions(+), 20 deletions(-)

Comments

Andrew Lunn March 28, 2017, 4:20 p.m.
On Tue, Mar 28, 2017 at 05:29:38PM +0200, Enric Balletbo i Serra wrote:
> From: Bryan Freed <bfreed@chromium.org>
> 
> When the I2C Infineon part is attached to an I2C adapter that imposes
> a size limitation, large requests will fail with -EOPNOTSUPP. Retry
> them with a sane minimum size without re-issuing the 0x05 command
> as this appears to occasionally put the TPM in a bad state.
> 
> Signed-off-by: Bryan Freed <bfreed@chromium.org>
> [rework the patch to adapt to the feedback received]
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

This looks O.K. now. Thanks for remembering the adaptor limit.

Acked-by: Andrew Lunn <andrew@lunn.ch>

    Andrew

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Jarkko Sakkinen March 31, 2017, 8:13 a.m.
On Tue, Mar 28, 2017 at 05:29:38PM +0200, Enric Balletbo i Serra wrote:
> From: Bryan Freed <bfreed@chromium.org>
> 
> When the I2C Infineon part is attached to an I2C adapter that imposes
> a size limitation, large requests will fail with -EOPNOTSUPP. Retry
> them with a sane minimum size without re-issuing the 0x05 command
> as this appears to occasionally put the TPM in a bad state.
> 
> Signed-off-by: Bryan Freed <bfreed@chromium.org>
> [rework the patch to adapt to the feedback received]
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
> ---
> This is a reworked version of the original patch based on the
> suggestion made by Wolfram Sang to simply fall back to a sane minimum
> when the maximum fails.
> 
> Changes since v2:
>  - Do not remove faster transfers when chip is SLB9645 (Peter Huewe)
>  - Remember the adapterlimit length once it fails to not generate extra
>    i2c core messages (suggested by Andrew Lunn)
> Changes since v1:
>  - Check the correct return value (-EOPNOTSUPP instead of -EINVAL)
>  - Fall back len to I2C_SMBUS_BLOCK_MAX if fails.
> 
>  drivers/char/tpm/tpm_i2c_infineon.c | 76 +++++++++++++++++++++++++++----------
>  1 file changed, 56 insertions(+), 20 deletions(-)

Looking into this after taking of the request for 4.12.

/Jarkko

> 
> diff --git a/drivers/char/tpm/tpm_i2c_infineon.c b/drivers/char/tpm/tpm_i2c_infineon.c
> index 62ee44e..fdefcdb 100644
> --- a/drivers/char/tpm/tpm_i2c_infineon.c
> +++ b/drivers/char/tpm/tpm_i2c_infineon.c
> @@ -70,6 +70,7 @@ struct tpm_inf_dev {
>  	u8 buf[TPM_BUFSIZE + sizeof(u8)]; /* max. buffer size + addr */
>  	struct tpm_chip *chip;
>  	enum i2c_chip_type chip_type;
> +	unsigned int adapterlimit;
>  };
>  
>  static struct tpm_inf_dev tpm_dev;
> @@ -111,6 +112,7 @@ static int iic_tpm_read(u8 addr, u8 *buffer, size_t len)
>  
>  	int rc = 0;
>  	int count;
> +	unsigned int msglen = len;
>  
>  	/* Lock the adapter for the duration of the whole sequence. */
>  	if (!tpm_dev.client->adapter->algo->master_xfer)
> @@ -131,27 +133,61 @@ static int iic_tpm_read(u8 addr, u8 *buffer, size_t len)
>  			usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
>  		}
>  	} else {
> -		/* slb9635 protocol should work in all cases */
> -		for (count = 0; count < MAX_COUNT; count++) {
> -			rc = __i2c_transfer(tpm_dev.client->adapter, &msg1, 1);
> -			if (rc > 0)
> -				break;	/* break here to skip sleep */
> -
> -			usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
> -		}
> -
> -		if (rc <= 0)
> -			goto out;
> -
> -		/* After the TPM has successfully received the register address
> -		 * it needs some time, thus we're sleeping here again, before
> -		 * retrieving the data
> +		/* Expect to send one command message and one data message, but
> +		 * support looping over each or both if necessary.
>  		 */
> -		for (count = 0; count < MAX_COUNT; count++) {
> -			usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
> -			rc = __i2c_transfer(tpm_dev.client->adapter, &msg2, 1);
> -			if (rc > 0)
> -				break;
> +		while (len > 0) {
> +			/* slb9635 protocol should work in all cases */
> +			for (count = 0; count < MAX_COUNT; count++) {
> +				rc = __i2c_transfer(tpm_dev.client->adapter,
> +						    &msg1, 1);
> +				if (rc > 0)
> +					break;	/* break here to skip sleep */
> +
> +				usleep_range(SLEEP_DURATION_LOW,
> +					     SLEEP_DURATION_HI);
> +			}
> +
> +			if (rc <= 0)
> +				goto out;
> +
> +			/* After the TPM has successfully received the register
> +			 * address it needs some time, thus we're sleeping here
> +			 * again, before retrieving the data
> +			 */
> +			for (count = 0; count < MAX_COUNT; count++) {
> +				if (tpm_dev.adapterlimit) {
> +					msglen = min_t(unsigned int,
> +						       tpm_dev.adapterlimit,
> +						       len);
> +					msg2.len = msglen;
> +				}
> +				usleep_range(SLEEP_DURATION_LOW,
> +					     SLEEP_DURATION_HI);
> +				rc = __i2c_transfer(tpm_dev.client->adapter,
> +						    &msg2, 1);
> +				if (rc > 0) {
> +					/* Since len is unsigned, make doubly
> +					 * sure we do not underflow it.
> +					 */
> +					if (msglen > len)
> +						len = 0;
> +					else
> +						len -= msglen;
> +					msg2.buf += msglen;
> +					break;
> +				}
> +				/* If the I2C adapter rejected the request (e.g
> +				 * when the quirk read_max_len < len) fall back
> +				 * to a sane minimum value and try again.
> +				 */
> +				if (rc == -EOPNOTSUPP)
> +					tpm_dev.adapterlimit =
> +							I2C_SMBUS_BLOCK_MAX;
> +			}
> +
> +			if (rc <= 0)
> +				goto out;
>  		}
>  	}
>  
> -- 
> 2.9.3
> 

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Jarkko Sakkinen April 5, 2017, 9:03 a.m.
On Tue, Mar 28, 2017 at 05:29:38PM +0200, Enric Balletbo i Serra wrote:
> From: Bryan Freed <bfreed@chromium.org>
> 
> When the I2C Infineon part is attached to an I2C adapter that imposes
> a size limitation, large requests will fail with -EOPNOTSUPP. Retry
> them with a sane minimum size without re-issuing the 0x05 command
> as this appears to occasionally put the TPM in a bad state.
> 
> Signed-off-by: Bryan Freed <bfreed@chromium.org>
> [rework the patch to adapt to the feedback received]
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
> ---
> This is a reworked version of the original patch based on the
> suggestion made by Wolfram Sang to simply fall back to a sane minimum
> when the maximum fails.
> 
> Changes since v2:
>  - Do not remove faster transfers when chip is SLB9645 (Peter Huewe)
>  - Remember the adapterlimit length once it fails to not generate extra
>    i2c core messages (suggested by Andrew Lunn)
> Changes since v1:
>  - Check the correct return value (-EOPNOTSUPP instead of -EINVAL)
>  - Fall back len to I2C_SMBUS_BLOCK_MAX if fails.
> 
>  drivers/char/tpm/tpm_i2c_infineon.c | 76 +++++++++++++++++++++++++++----------
>  1 file changed, 56 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_i2c_infineon.c b/drivers/char/tpm/tpm_i2c_infineon.c
> index 62ee44e..fdefcdb 100644
> --- a/drivers/char/tpm/tpm_i2c_infineon.c
> +++ b/drivers/char/tpm/tpm_i2c_infineon.c
> @@ -70,6 +70,7 @@ struct tpm_inf_dev {
>  	u8 buf[TPM_BUFSIZE + sizeof(u8)]; /* max. buffer size + addr */
>  	struct tpm_chip *chip;
>  	enum i2c_chip_type chip_type;
> +	unsigned int adapterlimit;
>  };
>  
>  static struct tpm_inf_dev tpm_dev;
> @@ -111,6 +112,7 @@ static int iic_tpm_read(u8 addr, u8 *buffer, size_t len)
>  
>  	int rc = 0;
>  	int count;
> +	unsigned int msglen = len;
>  
>  	/* Lock the adapter for the duration of the whole sequence. */
>  	if (!tpm_dev.client->adapter->algo->master_xfer)
> @@ -131,27 +133,61 @@ static int iic_tpm_read(u8 addr, u8 *buffer, size_t len)
>  			usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
>  		}
>  	} else {
> -		/* slb9635 protocol should work in all cases */
> -		for (count = 0; count < MAX_COUNT; count++) {
> -			rc = __i2c_transfer(tpm_dev.client->adapter, &msg1, 1);
> -			if (rc > 0)
> -				break;	/* break here to skip sleep */
> -
> -			usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
> -		}
> -
> -		if (rc <= 0)
> -			goto out;
> -
> -		/* After the TPM has successfully received the register address
> -		 * it needs some time, thus we're sleeping here again, before
> -		 * retrieving the data
> +		/* Expect to send one command message and one data message, but
> +		 * support looping over each or both if necessary.
>  		 */
> -		for (count = 0; count < MAX_COUNT; count++) {
> -			usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
> -			rc = __i2c_transfer(tpm_dev.client->adapter, &msg2, 1);
> -			if (rc > 0)
> -				break;
> +		while (len > 0) {
> +			/* slb9635 protocol should work in all cases */
> +			for (count = 0; count < MAX_COUNT; count++) {
> +				rc = __i2c_transfer(tpm_dev.client->adapter,
> +						    &msg1, 1);
> +				if (rc > 0)
> +					break;	/* break here to skip sleep */
> +
> +				usleep_range(SLEEP_DURATION_LOW,
> +					     SLEEP_DURATION_HI);
> +			}
> +
> +			if (rc <= 0)
> +				goto out;
> +
> +			/* After the TPM has successfully received the register
> +			 * address it needs some time, thus we're sleeping here
> +			 * again, before retrieving the data
> +			 */
> +			for (count = 0; count < MAX_COUNT; count++) {
> +				if (tpm_dev.adapterlimit) {
> +					msglen = min_t(unsigned int,
> +						       tpm_dev.adapterlimit,
> +						       len);
> +					msg2.len = msglen;
> +				}
> +				usleep_range(SLEEP_DURATION_LOW,
> +					     SLEEP_DURATION_HI);
> +				rc = __i2c_transfer(tpm_dev.client->adapter,
> +						    &msg2, 1);
> +				if (rc > 0) {
> +					/* Since len is unsigned, make doubly
> +					 * sure we do not underflow it.
> +					 */
> +					if (msglen > len)
> +						len = 0;
> +					else
> +						len -= msglen;
> +					msg2.buf += msglen;
> +					break;
> +				}
> +				/* If the I2C adapter rejected the request (e.g
> +				 * when the quirk read_max_len < len) fall back
> +				 * to a sane minimum value and try again.
> +				 */
> +				if (rc == -EOPNOTSUPP)
> +					tpm_dev.adapterlimit =
> +							I2C_SMBUS_BLOCK_MAX;
> +			}
> +
> +			if (rc <= 0)
> +				goto out;
>  		}
>  	}
>  
> -- 
> 2.9.3
> 

Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

Peter, Andrew, anyone: Tested-by?

/Jarkko

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Peter Hüwe April 5, 2017, 10:05 a.m.
Am 5. April 2017 11:03:27 MESZ schrieb Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>:
>On Tue, Mar 28, 2017 at 05:29:38PM +0200, Enric Balletbo i Serra wrote:
>> From: Bryan Freed <bfreed@chromium.org>
>> 
>> When the I2C Infineon part is attached to an I2C adapter that imposes
>> a size limitation, large requests will fail with -EOPNOTSUPP. Retry
>> them with a sane minimum size without re-issuing the 0x05 command
>> as this appears to occasionally put the TPM in a bad state.
>> 
>> Signed-off-by: Bryan Freed <bfreed@chromium.org>
>> [rework the patch to adapt to the feedback received]
>> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
>> ---
>> This is a reworked version of the original patch based on the
>> suggestion made by Wolfram Sang to simply fall back to a sane minimum
>> when the maximum fails.
>> 
>> Changes since v2:
>>  - Do not remove faster transfers when chip is SLB9645 (Peter Huewe)
>>  - Remember the adapterlimit length once it fails to not generate
>extra
>>    i2c core messages (suggested by Andrew Lunn)
>> Changes since v1:
>>  - Check the correct return value (-EOPNOTSUPP instead of -EINVAL)
>>  - Fall back len to I2C_SMBUS_BLOCK_MAX if fails.
>> 
>>  drivers/char/tpm/tpm_i2c_infineon.c | 76
>+++++++++++++++++++++++++++----------
>>  1 file changed, 56 insertions(+), 20 deletions(-)
>> 
>> diff --git a/drivers/char/tpm/tpm_i2c_infineon.c
>b/drivers/char/tpm/tpm_i2c_infineon.c
>> index 62ee44e..fdefcdb 100644
>> --- a/drivers/char/tpm/tpm_i2c_infineon.c
>> +++ b/drivers/char/tpm/tpm_i2c_infineon.c
>> @@ -70,6 +70,7 @@ struct tpm_inf_dev {
>>  	u8 buf[TPM_BUFSIZE + sizeof(u8)]; /* max. buffer size + addr */
>>  	struct tpm_chip *chip;
>>  	enum i2c_chip_type chip_type;
>> +	unsigned int adapterlimit;
>>  };
>>  
>>  static struct tpm_inf_dev tpm_dev;
>> @@ -111,6 +112,7 @@ static int iic_tpm_read(u8 addr, u8 *buffer,
>size_t len)
>>  
>>  	int rc = 0;
>>  	int count;
>> +	unsigned int msglen = len;
>>  
>>  	/* Lock the adapter for the duration of the whole sequence. */
>>  	if (!tpm_dev.client->adapter->algo->master_xfer)
>> @@ -131,27 +133,61 @@ static int iic_tpm_read(u8 addr, u8 *buffer,
>size_t len)
>>  			usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
>>  		}
>>  	} else {
>> -		/* slb9635 protocol should work in all cases */
>> -		for (count = 0; count < MAX_COUNT; count++) {
>> -			rc = __i2c_transfer(tpm_dev.client->adapter, &msg1, 1);
>> -			if (rc > 0)
>> -				break;	/* break here to skip sleep */
>> -
>> -			usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
>> -		}
>> -
>> -		if (rc <= 0)
>> -			goto out;
>> -
>> -		/* After the TPM has successfully received the register address
>> -		 * it needs some time, thus we're sleeping here again, before
>> -		 * retrieving the data
>> +		/* Expect to send one command message and one data message, but
>> +		 * support looping over each or both if necessary.
>>  		 */
>> -		for (count = 0; count < MAX_COUNT; count++) {
>> -			usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
>> -			rc = __i2c_transfer(tpm_dev.client->adapter, &msg2, 1);
>> -			if (rc > 0)
>> -				break;
>> +		while (len > 0) {
>> +			/* slb9635 protocol should work in all cases */
>> +			for (count = 0; count < MAX_COUNT; count++) {
>> +				rc = __i2c_transfer(tpm_dev.client->adapter,
>> +						    &msg1, 1);
>> +				if (rc > 0)
>> +					break;	/* break here to skip sleep */
>> +
>> +				usleep_range(SLEEP_DURATION_LOW,
>> +					     SLEEP_DURATION_HI);
>> +			}
>> +
>> +			if (rc <= 0)
>> +				goto out;
>> +
>> +			/* After the TPM has successfully received the register
>> +			 * address it needs some time, thus we're sleeping here
>> +			 * again, before retrieving the data
>> +			 */
>> +			for (count = 0; count < MAX_COUNT; count++) {
>> +				if (tpm_dev.adapterlimit) {
>> +					msglen = min_t(unsigned int,
>> +						       tpm_dev.adapterlimit,
>> +						       len);
>> +					msg2.len = msglen;
>> +				}
>> +				usleep_range(SLEEP_DURATION_LOW,
>> +					     SLEEP_DURATION_HI);
>> +				rc = __i2c_transfer(tpm_dev.client->adapter,
>> +						    &msg2, 1);
>> +				if (rc > 0) {
>> +					/* Since len is unsigned, make doubly
>> +					 * sure we do not underflow it.
>> +					 */
>> +					if (msglen > len)
>> +						len = 0;
>> +					else
>> +						len -= msglen;
>> +					msg2.buf += msglen;
>> +					break;
>> +				}
>> +				/* If the I2C adapter rejected the request (e.g
>> +				 * when the quirk read_max_len < len) fall back
>> +				 * to a sane minimum value and try again.
>> +				 */
>> +				if (rc == -EOPNOTSUPP)
>> +					tpm_dev.adapterlimit =
>> +							I2C_SMBUS_BLOCK_MAX;
>> +			}
>> +
>> +			if (rc <= 0)
>> +				goto out;
>>  		}
>>  	}
>>  
>> -- 
>> 2.9.3
>> 
>
>Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
>
>Peter, Andrew, anyone: Tested-by?
>

Not yet, I'll put it on my list to test.
Hopefully by next tuesday.
Peter

>/Jarkko
Andrew Lunn April 5, 2017, 1:24 p.m.
> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> 
> Peter, Andrew, anyone: Tested-by?

Sorry, i don't have the hardware. All i can give you is:

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew

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Jarkko Sakkinen April 5, 2017, 1:35 p.m.
On Wed, Apr 05, 2017 at 03:24:31PM +0200, Andrew Lunn wrote:
> > Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > 
> > Peter, Andrew, anyone: Tested-by?
> 
> Sorry, i don't have the hardware. All i can give you is:
> 
> Reviewed-by: Andrew Lunn <andrew@lunn.ch>
> 
>     Andrew

Thank you.

/Jarkko

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Jarkko Sakkinen April 5, 2017, 1:37 p.m.
On Wed, Apr 05, 2017 at 12:05:32PM +0200, Peter Huewe wrote:
> 
> 
> Am 5. April 2017 11:03:27 MESZ schrieb Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>:
> >On Tue, Mar 28, 2017 at 05:29:38PM +0200, Enric Balletbo i Serra wrote:
> >> From: Bryan Freed <bfreed@chromium.org>
> >> 
> >> When the I2C Infineon part is attached to an I2C adapter that imposes
> >> a size limitation, large requests will fail with -EOPNOTSUPP. Retry
> >> them with a sane minimum size without re-issuing the 0x05 command
> >> as this appears to occasionally put the TPM in a bad state.
> >> 
> >> Signed-off-by: Bryan Freed <bfreed@chromium.org>
> >> [rework the patch to adapt to the feedback received]
> >> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
> >> ---
> >> This is a reworked version of the original patch based on the
> >> suggestion made by Wolfram Sang to simply fall back to a sane minimum
> >> when the maximum fails.
> >> 
> >> Changes since v2:
> >>  - Do not remove faster transfers when chip is SLB9645 (Peter Huewe)
> >>  - Remember the adapterlimit length once it fails to not generate
> >extra
> >>    i2c core messages (suggested by Andrew Lunn)
> >> Changes since v1:
> >>  - Check the correct return value (-EOPNOTSUPP instead of -EINVAL)
> >>  - Fall back len to I2C_SMBUS_BLOCK_MAX if fails.
> >> 
> >>  drivers/char/tpm/tpm_i2c_infineon.c | 76
> >+++++++++++++++++++++++++++----------
> >>  1 file changed, 56 insertions(+), 20 deletions(-)
> >> 
> >> diff --git a/drivers/char/tpm/tpm_i2c_infineon.c
> >b/drivers/char/tpm/tpm_i2c_infineon.c
> >> index 62ee44e..fdefcdb 100644
> >> --- a/drivers/char/tpm/tpm_i2c_infineon.c
> >> +++ b/drivers/char/tpm/tpm_i2c_infineon.c
> >> @@ -70,6 +70,7 @@ struct tpm_inf_dev {
> >>  	u8 buf[TPM_BUFSIZE + sizeof(u8)]; /* max. buffer size + addr */
> >>  	struct tpm_chip *chip;
> >>  	enum i2c_chip_type chip_type;
> >> +	unsigned int adapterlimit;
> >>  };
> >>  
> >>  static struct tpm_inf_dev tpm_dev;
> >> @@ -111,6 +112,7 @@ static int iic_tpm_read(u8 addr, u8 *buffer,
> >size_t len)
> >>  
> >>  	int rc = 0;
> >>  	int count;
> >> +	unsigned int msglen = len;
> >>  
> >>  	/* Lock the adapter for the duration of the whole sequence. */
> >>  	if (!tpm_dev.client->adapter->algo->master_xfer)
> >> @@ -131,27 +133,61 @@ static int iic_tpm_read(u8 addr, u8 *buffer,
> >size_t len)
> >>  			usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
> >>  		}
> >>  	} else {
> >> -		/* slb9635 protocol should work in all cases */
> >> -		for (count = 0; count < MAX_COUNT; count++) {
> >> -			rc = __i2c_transfer(tpm_dev.client->adapter, &msg1, 1);
> >> -			if (rc > 0)
> >> -				break;	/* break here to skip sleep */
> >> -
> >> -			usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
> >> -		}
> >> -
> >> -		if (rc <= 0)
> >> -			goto out;
> >> -
> >> -		/* After the TPM has successfully received the register address
> >> -		 * it needs some time, thus we're sleeping here again, before
> >> -		 * retrieving the data
> >> +		/* Expect to send one command message and one data message, but
> >> +		 * support looping over each or both if necessary.
> >>  		 */
> >> -		for (count = 0; count < MAX_COUNT; count++) {
> >> -			usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
> >> -			rc = __i2c_transfer(tpm_dev.client->adapter, &msg2, 1);
> >> -			if (rc > 0)
> >> -				break;
> >> +		while (len > 0) {
> >> +			/* slb9635 protocol should work in all cases */
> >> +			for (count = 0; count < MAX_COUNT; count++) {
> >> +				rc = __i2c_transfer(tpm_dev.client->adapter,
> >> +						    &msg1, 1);
> >> +				if (rc > 0)
> >> +					break;	/* break here to skip sleep */
> >> +
> >> +				usleep_range(SLEEP_DURATION_LOW,
> >> +					     SLEEP_DURATION_HI);
> >> +			}
> >> +
> >> +			if (rc <= 0)
> >> +				goto out;
> >> +
> >> +			/* After the TPM has successfully received the register
> >> +			 * address it needs some time, thus we're sleeping here
> >> +			 * again, before retrieving the data
> >> +			 */
> >> +			for (count = 0; count < MAX_COUNT; count++) {
> >> +				if (tpm_dev.adapterlimit) {
> >> +					msglen = min_t(unsigned int,
> >> +						       tpm_dev.adapterlimit,
> >> +						       len);
> >> +					msg2.len = msglen;
> >> +				}
> >> +				usleep_range(SLEEP_DURATION_LOW,
> >> +					     SLEEP_DURATION_HI);
> >> +				rc = __i2c_transfer(tpm_dev.client->adapter,
> >> +						    &msg2, 1);
> >> +				if (rc > 0) {
> >> +					/* Since len is unsigned, make doubly
> >> +					 * sure we do not underflow it.
> >> +					 */
> >> +					if (msglen > len)
> >> +						len = 0;
> >> +					else
> >> +						len -= msglen;
> >> +					msg2.buf += msglen;
> >> +					break;
> >> +				}
> >> +				/* If the I2C adapter rejected the request (e.g
> >> +				 * when the quirk read_max_len < len) fall back
> >> +				 * to a sane minimum value and try again.
> >> +				 */
> >> +				if (rc == -EOPNOTSUPP)
> >> +					tpm_dev.adapterlimit =
> >> +							I2C_SMBUS_BLOCK_MAX;
> >> +			}
> >> +
> >> +			if (rc <= 0)
> >> +				goto out;
> >>  		}
> >>  	}
> >>  
> >> -- 
> >> 2.9.3
> >> 
> >
> >Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> >
> >Peter, Andrew, anyone: Tested-by?
> >
> 
> Not yet, I'll put it on my list to test.
> Hopefully by next tuesday.
> Peter

Ok, thanks. I can push this to my master branch if that would help
to ease the testig?

/Jarkko

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diff --git a/drivers/char/tpm/tpm_i2c_infineon.c b/drivers/char/tpm/tpm_i2c_infineon.c
index 62ee44e..fdefcdb 100644
--- a/drivers/char/tpm/tpm_i2c_infineon.c
+++ b/drivers/char/tpm/tpm_i2c_infineon.c
@@ -70,6 +70,7 @@  struct tpm_inf_dev {
 	u8 buf[TPM_BUFSIZE + sizeof(u8)]; /* max. buffer size + addr */
 	struct tpm_chip *chip;
 	enum i2c_chip_type chip_type;
+	unsigned int adapterlimit;
 };
 
 static struct tpm_inf_dev tpm_dev;
@@ -111,6 +112,7 @@  static int iic_tpm_read(u8 addr, u8 *buffer, size_t len)
 
 	int rc = 0;
 	int count;
+	unsigned int msglen = len;
 
 	/* Lock the adapter for the duration of the whole sequence. */
 	if (!tpm_dev.client->adapter->algo->master_xfer)
@@ -131,27 +133,61 @@  static int iic_tpm_read(u8 addr, u8 *buffer, size_t len)
 			usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
 		}
 	} else {
-		/* slb9635 protocol should work in all cases */
-		for (count = 0; count < MAX_COUNT; count++) {
-			rc = __i2c_transfer(tpm_dev.client->adapter, &msg1, 1);
-			if (rc > 0)
-				break;	/* break here to skip sleep */
-
-			usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
-		}
-
-		if (rc <= 0)
-			goto out;
-
-		/* After the TPM has successfully received the register address
-		 * it needs some time, thus we're sleeping here again, before
-		 * retrieving the data
+		/* Expect to send one command message and one data message, but
+		 * support looping over each or both if necessary.
 		 */
-		for (count = 0; count < MAX_COUNT; count++) {
-			usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
-			rc = __i2c_transfer(tpm_dev.client->adapter, &msg2, 1);
-			if (rc > 0)
-				break;
+		while (len > 0) {
+			/* slb9635 protocol should work in all cases */
+			for (count = 0; count < MAX_COUNT; count++) {
+				rc = __i2c_transfer(tpm_dev.client->adapter,
+						    &msg1, 1);
+				if (rc > 0)
+					break;	/* break here to skip sleep */
+
+				usleep_range(SLEEP_DURATION_LOW,
+					     SLEEP_DURATION_HI);
+			}
+
+			if (rc <= 0)
+				goto out;
+
+			/* After the TPM has successfully received the register
+			 * address it needs some time, thus we're sleeping here
+			 * again, before retrieving the data
+			 */
+			for (count = 0; count < MAX_COUNT; count++) {
+				if (tpm_dev.adapterlimit) {
+					msglen = min_t(unsigned int,
+						       tpm_dev.adapterlimit,
+						       len);
+					msg2.len = msglen;
+				}
+				usleep_range(SLEEP_DURATION_LOW,
+					     SLEEP_DURATION_HI);
+				rc = __i2c_transfer(tpm_dev.client->adapter,
+						    &msg2, 1);
+				if (rc > 0) {
+					/* Since len is unsigned, make doubly
+					 * sure we do not underflow it.
+					 */
+					if (msglen > len)
+						len = 0;
+					else
+						len -= msglen;
+					msg2.buf += msglen;
+					break;
+				}
+				/* If the I2C adapter rejected the request (e.g
+				 * when the quirk read_max_len < len) fall back
+				 * to a sane minimum value and try again.
+				 */
+				if (rc == -EOPNOTSUPP)
+					tpm_dev.adapterlimit =
+							I2C_SMBUS_BLOCK_MAX;
+			}
+
+			if (rc <= 0)
+				goto out;
 		}
 	}