linux-kernel - Re: [PATCH v2 1/4] i2c: imx: only poll for bus busy in multi master mode

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Message-ID: <ZsX8KzkQw0wJUCbc@pengutronix.de>
Date: Wed, 21 Aug 2024 16:39:39 +0200
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: Fabio Estevam <festevam@...il.com>
Cc: Stefan Eichenberger <eichest@...il.com>, kernel@...gutronix.de,
	andi.shyti@...nel.org, shawnguo@...nel.org, s.hauer@...gutronix.de,
	Frank.Li@....com, francesco.dolcini@...adex.com,
	linux-i2c@...r.kernel.org, imx@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Stefan Eichenberger <stefan.eichenberger@...adex.com>
Subject: Re: [PATCH v2 1/4] i2c: imx: only poll for bus busy in multi master
 mode

Hi Fabio, Stefan,

On Wed, Aug 21, 2024 at 08:01:20AM -0300, Fabio Estevam wrote:
> Hi Stefan,
> 
> On Mon, Aug 19, 2024 at 4:20 AM Stefan Eichenberger <eichest@...il.com> wrote:
> >
> > From: Stefan Eichenberger <stefan.eichenberger@...adex.com>
> >
> > According to the i.MX8M Mini reference manual chapter "16.1.4.2
> > Generation of Start" it is only necessary to poll for bus busy and
> > arbitration lost in multi master mode. This helps to avoid rescheduling
> > while the i2c bus is busy and avoids SMBus devices to timeout.
> >
> > Signed-off-by: Stefan Eichenberger <stefan.eichenberger@...adex.com>
> > Reviewed-by: Frank Li <Frank.Li@....com>
> 
> This fixes a pca953x probe error on an imx8mp board running linux-stable 6.6:
> 
> [    1.893260] pca953x 2-0020: failed writing register
> [    1.898258] pca953x 2-0020: probe with driver pca953x failed with error -11
> 
> Could you please add a Fixes tag and Cc stable so that this can reach
> the stable kernels?
> 
> Tested-by: Fabio Estevam <festevam@...x.de>
> 
> Thanks a lot,

It looks like with this patch, the I2SR_IAL interrupt is not cleared.
I would expect some kind of interrupt storm. Can you confirm it?

Regards,
Oleksij
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