From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Lunn Subject: Re: Atmel I2C TPM transfer length issues Date: Tue, 14 Feb 2017 14:05:11 +0100 Message-ID: <20170214130511.GA32480@lunn.ch> References: <20170214023336.GC21340@lunn.ch> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: tpmdd-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Peter Huewe Cc: tpmdd-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: tpmdd-devel@lists.sourceforge.net > Just limit the value which get_burstcount() returns to 256. > > This should do the trick - because that would be the mechanism the > tpm itself would use to fragment its response. Atleast for other > tpms like our infineon slb9645 i2c tpm that would work. Yes, that was one idea i had. But then i found the comment on the top of tpm_i2c_atmel: * Teddy Reed determined the basic I2C command flow, unlike other I2C TPM * devices the raw TCG formatted TPM command data is written via I2C and then * raw TCG formatted TPM command data is returned via I2C. The driver does not do anything like read the burst size and then transfer in blocks. It reads/writes all in one go. However, you have answered what was going to be a follow question. The hardware is not yet set in stone. We could change the TPM. Use the Infinion TPM with a modified get_burstcount(). And you think this will work. Great. Thanks Andrew ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot