linux-kernel - Re: [PATCH 2/4] i2c: stm32f7: recover the bus on access timeout

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Message-ID: <YaTNDq7rEyQIopim@kunai>
Date:   Mon, 29 Nov 2021 13:52:30 +0100
From:   Wolfram Sang <wsa@...nel.org>
To:     pierre-yves.mordret@...s.st.com, alexandre.torgue@...s.st.com,
        linux-i2c@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        fabrice.gasnier@...s.st.com, amelie.delaunay@...s.st.com
Subject: Re: [PATCH 2/4] i2c: stm32f7: recover the bus on access timeout

Hi Alain,

> > > +		stm32f7_i2c_wait_free_bus(i2c_dev);
> > 
> > This does only a controller reset, not a bus recovery with 9 toggling
> > pulses, or?
> 
> indeed. I might better rework this and at the same time introduce the
> bus recovery mechanism via the bus recovery callback in this driver.
> Please don't merge this patch and I will rework that.

Wait a sec. Resetting a controller at the end of a failed transfer might
make sense if the controller is otherwise in an confused state.

Full bus recovery (9 pulses) should be done at the beginning of a
transfer when SDA is low, though.

So, I'd actually suggest to apply this patch and add full bus recovery
based on SDA low at the beginning of a transfer seperately.

What do you think?

All the best,

   Wolfram

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