linux-kernel - Re: [PATCH v5 07/10] i2c: npcm: Handle spurious interrupts

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Date:   Sat, 21 May 2022 21:00:35 +0800
From:   Tyrone Ting <warp5tw@...il.com>
To:     Wolfram Sang <wsa@...nel.org>, Tyrone Ting <warp5tw@...il.com>,
        avifishman70@...il.com, tmaimon77@...il.com, tali.perry1@...il.com,
        venture@...gle.com, yuenn@...gle.com, benjaminfair@...gle.com,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        andriy.shevchenko@...ux.intel.com, jarkko.nikula@...ux.intel.com,
        semen.protsenko@...aro.org, rafal@...ecki.pl, sven@...npeter.dev,
        jsd@...ihalf.com, lukas.bulwahn@...il.com, arnd@...db.de,
        olof@...om.net, tali.perry@...oton.com, Avi.Fishman@...oton.com,
        tomer.maimon@...oton.com, KWLIU@...oton.com, JJLIU0@...oton.com,
        kfting@...oton.com, openbmc@...ts.ozlabs.org,
        linux-i2c@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     jie.deng@...el.com
Subject: Re: [PATCH v5 07/10] i2c: npcm: Handle spurious interrupts

Hi Wolfram:

Thank you for your review.

Wolfram Sang <wsa@...nel.org> 於 2022年5月21日 週六 下午1:53寫道：
>
> On Tue, May 17, 2022 at 06:11:39PM +0800, Tyrone Ting wrote:
> > From: Tali Perry <tali.perry1@...il.com>
> >
> > On some platforms in rare cases (1 to 100,000 transactions),
> > the i2c gets a spurious interrupt which means that we enter an interrupt
> > but in the interrupt handler we don't find any status bit that points to
> > 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 not
> >    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 driver")
> > Signed-off-by: Tali Perry <tali.perry1@...il.com>
> > Signed-off-by: Tyrone Ting <kfting@...oton.com>
>
> Applied to for-next, thanks!
>

Best Regards,
Tyrone