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Subject: Re: [PATCH] i2c: stm32f7: Add atomic_xfer method to driver
From:   Sean Nyekjaer <sean@geanix.com>
In-Reply-To: <ZJV0/cbjn1Qa62u+@shikoro>
Date:   Mon, 3 Jul 2023 11:00:31 +0200
Cc:     Pierre-Yves MORDRET <pierre-yves.mordret@foss.st.com>,
        Alain Volmat <alain.volmat@foss.st.com>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        linux-i2c@vger.kernel.org,
        linux-stm32@st-md-mailman.stormreply.com,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
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Message-Id: <9BEDFE6D-AE5E-46F1-A1BF-A19C6F5130F6@geanix.com>
References: <20230509132159.4160984-1-sean@geanix.com>
 <ZJV0/cbjn1Qa62u+@shikoro>
To:     Wolfram Sang <wsa@kernel.org>
Precedence: bulk


> On 23 Jun 2023, at 12.33, Wolfram Sang <wsa@kernel.org> wrote:
>=20
> On Tue, May 09, 2023 at 03:21:59PM +0200, Sean Nyekjaer wrote:
>> Add an atomic_xfer method to the driver so that it behaves correctly
>> when controlling a PMIC that is responsible for device shutdown.
>>=20
>> The atomic_xfer method added is similar to the one from the =
i2c-mv64xxx
>> driver. When running an atomic_xfer a bool flag in the driver data is
>> set, the interrupt is not unmasked on transfer start, and the IRQ
>> handler is manually invoked while waiting for pending transfers to
>> complete.
>>=20
>> Signed-off-by: Sean Nyekjaer <sean@geanix.com>
>=20
> Pierre-Yves, Alain, any further comments to this patch?
>=20
>> Is it okay to keep the DMA transfer in atomic?
>=20
> Will DMA actually run in atomic mode?
>=20

Hi Wolfram,

Atomic is mainly(only) used for writing a single register in the PMIC =
for the stpmic. Guess that will not trigger any DMA use.
But let=E2=80=99s wait for other comments=E2=80=A6

/Sean=