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

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Message-ID: <Yoh+YZestxT7oG8B@shikoro>
Date:   Sat, 21 May 2022 07:53:37 +0200
From:   Wolfram Sang <wsa@...nel.org>
To:     Tyrone Ting <warp5tw@...il.com>
Cc:     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, jie.deng@...el.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
Subject: Re: [PATCH v5 07/10] i2c: npcm: Handle spurious interrupts

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!


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