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Date: Wed, 22 Feb 2017 15:01:34 +0100
From: Andrew Lunn <andrew@lunn.ch>
To: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Cc: Peter Huewe <peterhuewe@gmx.de>, Marcel Selhorst <tpmdd@selhorst.net>,
        apronin@google.com, tpmdd-devel@lists.sourceforge.net,
        linux-kernel@vger.kernel.org, Wolfram Sang <wsa@the-dreams.de>
Subject: Re: [tpmdd-devel] [PATCH 1/2] tpm: Apply an adapterlimit for
 retransmission.
Message-ID: <20170222140134.GA23586@lunn.ch>
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On Wed, Feb 22, 2017 at 12:16:08PM +0100, Enric Balletbo i Serra wrote:
> Hi Andrew,
> 
> Removing Bryan Freed from the loop as seems his email is not valid anymore. I already CC'ied Andrey which is doing the TPM bit in chromeos kernel.
> 
> On 21/02/17 17:29, Andrew Lunn wrote:
> > On Tue, Feb 21, 2017 at 03:44:59PM +0100, 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 -EINVAL.
> >> Retry them with size backoff without re-issuing the 0x05 command
> >> as this appears to occasionally put the TPM in a bad state.
> > 
> > Hi Enric
> > 
> > Rather than trying small and smaller transfers, would it not be better
> > to get the i2c core to expose the quirk info about transfer limits?
> > 
> 
> Sounds a good idea to me, I guess the quirk info can be accessed with
> 
>   tpm_dev.client->adapter->quirks->max_read_len
> 
> so I think we don't need to touch the i2c core. I'll propose a second version of the patch.

Hi Enric

You should probably ask Wolfram Sang <wsa@the-dreams.de>, the i2c
subsystem maintainer. He may prefer adding an API call.

	  Andrew