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From:   Tyrone Ting <warp5tw@gmail.com>
Date:   Sat, 21 May 2022 21:00:35 +0800
Message-ID: <CACD3sJbcOdCED24Fno-jd1z0T21KuJ_hTWNQcSHqhbxaZZaXwA@mail.gmail.com>
Subject: Re: [PATCH v5 07/10] i2c: npcm: Handle spurious interrupts
To:     Wolfram Sang <wsa@kernel.org>, Tyrone Ting <warp5tw@gmail.com>,
        avifishman70@gmail.com, tmaimon77@gmail.com, tali.perry1@gmail.com,
        venture@google.com, yuenn@google.com, benjaminfair@google.com,
        robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org,
        andriy.shevchenko@linux.intel.com, jarkko.nikula@linux.intel.com,
        semen.protsenko@linaro.org, rafal@milecki.pl, sven@svenpeter.dev,
        jsd@semihalf.com, lukas.bulwahn@gmail.com, arnd@arndb.de,
        olof@lixom.net, tali.perry@nuvoton.com, Avi.Fishman@nuvoton.com,
        tomer.maimon@nuvoton.com, KWLIU@nuvoton.com, JJLIU0@nuvoton.com,
        kfting@nuvoton.com, openbmc@lists.ozlabs.org,
        linux-i2c@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     jie.deng@intel.com
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Hi Wolfram:

Thank you for your review.

Wolfram Sang <wsa@kernel.org> =E6=96=BC 2022=E5=B9=B45=E6=9C=8821=E6=97=A5 =
=E9=80=B1=E5=85=AD =E4=B8=8B=E5=8D=881:53=E5=AF=AB=E9=81=93=EF=BC=9A
>
> On Tue, May 17, 2022 at 06:11:39PM +0800, Tyrone Ting wrote:
> > From: Tali Perry <tali.perry1@gmail.com>
> >
> > On some platforms in rare cases (1 to 100,000 transactions),
> > the i2c gets a spurious interrupt which means that we enter an interrup=
t
> > but in the interrupt handler we don't find any status bit that points t=
o
> > the reason we got this interrupt.
> >
> > This may be a case of a rare HW issue or signal integrity issue that is
> > still under investigation.
> >
> > In order to overcome this we are doing the following:
> > 1. Disable incoming interrupts in master mode only when slave mode is n=
ot
> >    enabled.
> > 2. Clear end of busy (EOB) after every interrupt.
> > 3. Clear other status bits (just in case since we found them cleared)
> > 4. Return correct status during the interrupt that will finish the
> >    transaction.
> >
> > On next xmit transaction if the bus is still busy the master will issue=
 a
> > recovery process before issuing the new transaction.
> >
> > Fixes: 56a1485b102e ("i2c: npcm7xx: Add Nuvoton NPCM I2C controller dri=
ver")
> > Signed-off-by: Tali Perry <tali.perry1@gmail.com>
> > Signed-off-by: Tyrone Ting <kfting@nuvoton.com>
>
> Applied to for-next, thanks!
>

Best Regards,
Tyrone