linux-kernel - Re: [PATCH v1] i2c: imx: fix missing stop condition in single-master mode

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Message-ID: <20241216184231.GA53492@francesco-nb>
Date: Mon, 16 Dec 2024 19:42:31 +0100
From: Francesco Dolcini <francesco@...cini.it>
To: Stefan Eichenberger <eichest@...il.com>
Cc: o.rempel@...gutronix.de, kernel@...gutronix.de, andi.shyti@...nel.org,
	shawnguo@...nel.org, s.hauer@...gutronix.de, festevam@...il.com,
	Frank.Li@....com, stefan.eichenberger@...adex.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
Subject: Re: [PATCH v1] i2c: imx: fix missing stop condition in single-master
 mode

On Mon, Dec 16, 2024 at 04:16:40PM +0100, Stefan Eichenberger wrote:
> From: Stefan Eichenberger <stefan.eichenberger@...adex.com>
> 
> A regression was introduced with the implementation of single-master
> mode, preventing proper stop conditions from being generated. Devices
> that require a valid stop condition, such as EEPROMs, fail to function
> correctly as a result.
> 
> The issue only affects devices with the single-master property enabled.
> 
> This commit resolves the issue by re-enabling I2C bus busy bit (IBB)
> polling for single-master mode when generating a stop condition. The fix
> further ensures that the i2c_imx->stopped flag is cleared at the start
> of each transfer, allowing the stop condition to be correctly generated
> in i2c_imx_stop().
> 
> According to the reference manual (IMX8MMRM, Rev. 2, 09/2019, page
> 5270), polling the IBB bit to determine if the bus is free is only
> necessary in multi-master mode. Consequently, the IBB bit is not polled
> for the start condition in single-master mode.
> 
> Fixes: 6692694aca86 ("i2c: imx: do not poll for bus busy in single master mode")
> Signed-off-by: Stefan Eichenberger <stefan.eichenberger@...adex.com>

Reviewed-by: Francesco Dolcini <francesco.dolcini@...adex.com>