linux-kernel - Re: [PATCH v2 2/3] i2c: imx: Check for I2SR

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Message-ID: <20201005080725.GB7135@kozik-lap>
Date:   Mon, 5 Oct 2020 10:07:25 +0200
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Christian Eggers <ceggers@...i.de>
Cc:     Oleksij Rempel <linux@...pel-privat.de>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        NXP Linux Team <linux-imx@....com>,
        linux-i2c@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v2 2/3] i2c: imx: Check for I2SR_IAL after every byte

On Fri, Oct 02, 2020 at 05:23:04PM +0200, Christian Eggers wrote:
> Arbitration Lost (IAL) can happen after every single byte transfer. If
> arbitration is lost, the I2C hardware will autonomously switch from
> master mode to slave. If a transfer is not aborted in this state,
> consecutive transfers will not be executed by the hardware and will
> timeout.
> 
> Signed-off-by: Christian Eggers <ceggers@...i.de>
> Cc: stable@...r.kernel.org
> ---
>  drivers/i2c/busses/i2c-imx.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 

Tested (not extensively) on Vybrid VF500 (Toradex VF50):
Tested-by: Krzysztof Kozlowski <krzk@...nel.org>

The I2C on Vybrid VF500 still works fine. I did not test this actual
condition (arbitration) but only a regular I2C driver (BQ27xxx fuel
gauge). Obviously this only proves that regular operation is not
broken...

Alternatively if you have a specific testing procedure (reproduction of
a problem), please share.

Best regards,
Krzysztof