linux-kernel - Re: [PATCH v2] i2c: mv64xxx: Add bus error recovery

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Message-ID: <20200825092613.GJ1861@ninjato>
Date:   Tue, 25 Aug 2020 11:26:13 +0200
From:   Wolfram Sang <wsa@...nel.org>
To:     Mark Tomlinson <mark.tomlinson@...iedtelesis.co.nz>
Cc:     gregory.clement@...tlin.com, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] i2c: mv64xxx: Add bus error recovery

On Tue, Aug 25, 2020 at 10:52:54AM +1200, Mark Tomlinson wrote:
> This adds i2c bus recovery to the mv64xxx driver.
> 
> Implement bus recovery to recover from SCL/SDA stuck low.
> 
> This uses the generic recovery function, setting the clock/data lines as
> GPIO pins, and sending 9 clocks to try and recover the bus.
> 
> Signed-off-by: Mark Tomlinson <mark.tomlinson@...iedtelesis.co.nz>
> ---
> Changes in v2:
>  - use generic GPIO recovery function.

Thank you for doing that! Glad to see the new helper function works for
you as well. The initialization code is all well, but I wonder about the
use of i2c_recover_bus(). Recovery should be tried only if it is
detected that SDA is pulled low when the bus should be free. So, you
shouldn't call i2c_recover_bus() in unconditionally in probe(). Can your
HW detect if SDA is stuck low?

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