linux-kernel - Re: [tpmdd-devel] [PATCH v2] tpm: Apply a sane minimum adapterlimit value for retransmission.

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Message-ID: <584dcb98-a78c-a070-465f-52e977650e5e@collabora.com>
Date:   Thu, 2 Mar 2017 18:31:03 +0100
From:   Enric Balletbo i Serra <enric.balletbo@...labora.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Peter Huewe <peterhuewe@....de>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        wsa@...-dreams.de, tpmdd-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, Bryan Freed <bfreed@...omium.org>
Subject: Re: [tpmdd-devel] [PATCH v2] tpm: Apply a sane minimum adapterlimit
 value for retransmission.

Hi Andrew,

On 02/03/17 18:24, Andrew Lunn wrote:
>>>> Hi Enric
>>>>
>>>> Maybe you should remember that you need to use smaller transfers? If
>>>> you don't remember, but use the full size message every time and only
>>>> drop back on error, the i2c core is going to log rate limited
>>>> messages. By remembering, there will only be one such message in the
>>>> log.
>>>>
>>
> 
>> Maybe I did not explain well but this is what the code does, when
>> i2c-core fails with -EOPNOTSUPP because the msg is too long for this
>> adapter it loop with a smaller chunk of fixed size, so you only see
>> the i2c-core message once.
> 
> Hi Enric
> 
> Would it not be more accurate to say, that you only see the i2c-core
> message once, for this transfer request. Is the next transfer request
> again going to use the longer length? then fail, maybe generate
> another i2c core message, depending on rate limiting, and then use the
> lower message size? I think it does.
> 
> Which is why i suggested remembering the length.
> 

Ah ok, sorry I did not understand you, got it now. Yes, so with this every time you do, i.e. a tpm_getpubek, you will see the i2c-core message, right. Thanks. Sounds a good suggestion for me.

Cheers,
 Enric

>       Andrew
>