linux-kernel - Re: [PATCH v2] watchdog: da9062: make restart handler atomic safe

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Date:   Sun, 19 Jan 2020 12:34:47 +0100
From:   Stefan Lengfeld <contact@...fanchrist.eu>
To:     Marco Felsch <m.felsch@...gutronix.de>
Cc:     support.opensource@...semi.com, linux@...ck-us.net,
        Adam.Thomson.Opensource@...semi.com,
        linux-watchdog@...r.kernel.org, kernel@...gutronix.de,
        linux-kernel@...r.kernel.org,
        Stefan Riedmueller <s.riedmueller@...tec.de>
Subject: Re: [PATCH v2] watchdog: da9062: make restart handler atomic safe

Hi Marco,

On Thu, Jan 16, 2020 at 08:23:20AM +0100, Stefan Lengfeld wrote:
> On Wed, Jan 15, 2020 at 05:23:07PM +0100, Marco Felsch wrote:
> > The restart handler is executed during the shutdown phase which is
> > atomic/irq-less. The i2c framework supports atomic transfers since
> > commit 63b96983a5dd ("i2c: core: introduce callbacks for atomic
> > transfers") to address this use case. Using regmap within an atomic
> > context is allowed only if the regmap type is MMIO and the cache type
> > 'flat' or no cache is used. Using the i2c_smbus_write_byte_data()
> > function can be done without additional tests because:
> >  1) the DA9062 is an i2c-only device and
> >  2) the i2c framework emulates the smbus protocol if the host adapter
> >     does not support smbus_xfer by using the master_xfer.
> > 
> > Signed-off-by: Marco Felsch <m.felsch@...gutronix.de>
> 
> Reviewed-by: Stefan Lengfeld <contact@...fanchrist.eu>

Now also 

Tested-by: Stefan Lengfeld <contact@...fanchrist.eu>

on a phyCORE-i.MX6 Quad with baseboard phyBOARD-Mira.

I'm also cc'ing Stefan from phytec, since he is also interested in the
thread/patch [1].

Kind regards,
    Stefan

[1]: https://www.spinics.net/lists/linux-watchdog/msg17203.html