From: Stefan Eichenberger <eichest@gmail.com>
To: Frank Li <Frank.li@nxp.com>
Cc: o.rempel@pengutronix.de, kernel@pengutronix.de,
andi.shyti@kernel.org, s.hauer@pengutronix.de,
festevam@gmail.com, stefan.eichenberger@toradex.com,
francesco.dolcini@toradex.com, linux-i2c@vger.kernel.org,
imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH v1 2/2] i2c: imx: ensure no clock is generated after last read
Date: Wed, 18 Feb 2026 17:37:54 +0100 [thread overview]
Message-ID: <aZXq4gn4xhInQQlq@eichest-laptop> (raw)
In-Reply-To: <aZXoTGK_v3L4pc-E@lizhi-Precision-Tower-5810>
Hi Frank,
On Wed, Feb 18, 2026 at 11:26:52AM -0500, Frank Li wrote:
> On Wed, Feb 18, 2026 at 04:08:50PM +0100, Stefan Eichenberger wrote:
> > From: Stefan Eichenberger <stefan.eichenberger@toradex.com>
> >
> > When reading from the I2DR register, right after releasing the bus by
> > clearing MSTA and MTX, the I2C controller might still generate an
> > additional clock cycle which can cause devices to misbehave. Ensure to
>
> Do you means SCL have additional toggle? You capture waveform?
>
Yes exactly. We were able to capture the waveform when the issue
happens. It doesn't always happen though, it depends on how much time
passes between clearing MSTA and MTX and reading from I2DR.
If you want to see the waveform, I uploaded it to our server:
https://share.toradex.com/dwnhcrl6b9toib6
You can see the additional clock at the right end, after "0x17 + NAK".
Regards,
Stefan
next prev parent reply other threads:[~2026-02-18 16:38 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-18 15:08 [PATCH v1 0/2] i2c: imx: fix i2c issues when reading messages Stefan Eichenberger
2026-02-18 15:08 ` [PATCH v1 1/2] i2c: imx: fix i2c issue when reading multiple messages Stefan Eichenberger
2026-02-18 16:22 ` Frank Li
2026-02-18 15:08 ` [PATCH v1 2/2] i2c: imx: ensure no clock is generated after last read Stefan Eichenberger
2026-02-18 16:26 ` Frank Li
2026-02-18 16:37 ` Stefan Eichenberger [this message]
2026-03-03 9:14 ` Stefan Eichenberger
2026-03-03 15:53 ` Frank Li
2026-03-04 3:00 ` Carlos Song
2026-03-19 23:09 ` Andi Shyti
2026-03-20 2:04 ` [EXT] " Carlos Song
2026-03-25 17:32 ` [PATCH v1 0/2] i2c: imx: fix i2c issues when reading messages Andi Shyti
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