[EXT] Re: [PATCH v3] i2c: imx-lpi2c: directly return ISR when detect a NACK

[Carlos Song]

> -----Original Message-----
> From: Andi Shyti <andi.shyti at kernel.org>
> Sent: Wednesday, July 26, 2023 10:52 PM
> To: Carlos Song <carlos.song at nxp.com>
> Cc: Aisheng Dong <aisheng.dong at nxp.com>; shawnguo at kernel.org;
> s.hauer at pengutronix.de; kernel at pengutronix.de; festevam at gmail.com; Clark
> Wang <xiaoning.wang at nxp.com>; Bough Chen <haibo.chen at nxp.com>;
> dl-linux-imx <linux-imx at nxp.com>; linux-i2c at vger.kernel.org;
> linux-arm-kernel at lists.infradead.org; linux-kernel at vger.kernel.org
> Subject: [EXT] Re: [PATCH v3] i2c: imx-lpi2c: directly return ISR when detect a
> NACK
> 
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> 
> Hi Carlos,
> 
> On Wed, Jul 26, 2023 at 05:23:50PM +0800, carlos.song at nxp.com wrote:
> > From: Carlos Song <carlos.song at nxp.com>
> >
> > A NACK flag in ISR means i2c bus error. In such condition, there is no
> > need to do read/write operation.
> >
> > In this patch, i2c will check MSR_NDF, MSR_RDF and MSR_TDF flag in
> > turn, it's making mutually exclusive NACK/read/write.
> > So when a NACK is received(MSR_NDF), i2c will return ISR directly and
> > then stop i2c transfer.
> 
> Very good, thank you!
> 
> > Fixes: a55fa9d0e42e ("i2c: imx-lpi2c: add low power i2c bus driver")
> 
> One last little question here. I want to know if this is actually fixing something or
> cleaning the exit path. What I mean is:
> can the device ever send an NDF along with an RDF or TDF?
> 
> If not, this "Fixes:" tag should be removed and this patch can be considered a
> cleanup. Otherwise would be nice to know what failure are you fixing.
> 
> I'm just trying to understand here :)
>
> Andi


Hi, Andi,
Yes, no failure to fix just a cleanup. I will remove it and resend v4.