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From: Stefan Lengfeld <contact@stefanchrist.eu>
To: Marco Felsch <m.felsch@pengutronix.de>
Cc: support.opensource@diasemi.com, linux@roeck-us.net,
	Adam.Thomson.Opensource@diasemi.com,
	linux-watchdog@vger.kernel.org, kernel@pengutronix.de,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] watchdog: da9062: make restart handler atomic safe
Date: Thu, 16 Jan 2020 08:23:20 +0100
Message-ID: <20200116072320.f7ia3e76hx7yknqb@porty> (raw)
In-Reply-To: <20200115162307.7336-1-m.felsch@pengutronix.de>

Hi Marco,

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@pengutronix.de>

Reviewed-by: Stefan Lengfeld <contact@stefanchrist.eu>


On Wed, Marco Flesch wrote [1]:
> I will send a v2 to cover Guenter's suggestion. Can I keep your reviewed
> by tag?

Yes, you can keep it. See above. I also checked by reading the code that
'i2c_smbus_write_byte_data' behaves the same as 'i2c_transfer'. Just
with some indirections.

Kind regards,
    Stefan

[1]: https://www.spinics.net/lists/linux-watchdog/msg17194.html

      parent reply index

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-15 16:23 Marco Felsch
2020-01-15 16:54 ` Guenter Roeck
2020-01-16  7:23 ` Stefan Lengfeld [this message]

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