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From: Krzysztof Kozlowski <krzk@kernel.org>
To: Christian Eggers <ceggers@arri.de>
Cc: "Oleksij Rempel" <linux@rempel-privat.de>,
	"Shawn Guo" <shawnguo@kernel.org>,
	"Sascha Hauer" <s.hauer@pengutronix.de>,
	"Fabio Estevam" <festevam@gmail.com>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	"Pengutronix Kernel Team" <kernel@pengutronix.de>,
	"NXP Linux Team" <linux-imx@nxp.com>,
	linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH v2 3/3] i2c: imx: Don't generate STOP condition if arbitration has been lost
Date: Mon, 5 Oct 2020 10:16:39 +0200
Message-ID: <20201005081639.GA7431@kozik-lap> (raw)
In-Reply-To: <20201002152305.4963-4-ceggers@arri.de>

On Fri, Oct 02, 2020 at 05:23:05PM +0200, Christian Eggers wrote:
> If arbitration is lost, the master automatically changes to slave mode.
> I2SR_IBB may or may not be reset by hardware. Raising a STOP condition
> by resetting I2CR_MSTA has no effect and will not clear I2SR_IBB.
> 
> So calling i2c_imx_bus_busy() is not required and would busy-wait until
> timeout.
> 
> Signed-off-by: Christian Eggers <ceggers@arri.de>
> Cc: stable@vger.kernel.org # Requires trivial backporting, simple remove
>                            # the 3rd argument from the calls to
>                            # i2c_imx_bus_busy().
> ---
>  drivers/i2c/busses/i2c-imx.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 

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

The I2C on Vybrid VF500 still works fine (also bigger transfers). 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...

Best regards,
Krzysztof

      reply index

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-02 15:23 [PATCH v2 0/3] i2c: imx: Fix handling of arbitration loss Christian Eggers
2020-10-02 15:23 ` [PATCH v2 1/3] i2c: imx: Fix reset of I2SR_IAL flag Christian Eggers
2020-10-05  8:05   ` Krzysztof Kozlowski
2020-10-06  6:05   ` Uwe Kleine-König
2020-10-06 10:51     ` [PATCH v3 0/3] i2c: imx: Fix handling of arbitration loss Christian Eggers
2020-10-06 10:51       ` [PATCH v3 1/3] i2c: imx: Fix reset of I2SR_IAL flag Christian Eggers
2020-10-06 12:06         ` David Laight
2020-10-06 12:30           ` Christian Eggers
2020-10-06 12:46           ` Uwe Kleine-König
2020-10-06 12:52             ` David Laight
2020-10-06 10:51       ` [PATCH v3 2/3] i2c: imx: Check for I2SR_IAL after every byte Christian Eggers
2020-10-06 10:51       ` [PATCH v3 3/3] i2c: imx: Don't generate STOP condition if arbitration has been lost Christian Eggers
2020-10-02 15:23 ` [PATCH v2 2/3] i2c: imx: Check for I2SR_IAL after every byte Christian Eggers
2020-10-05  8:07   ` Krzysztof Kozlowski
2020-10-05  9:25     ` Christian Eggers
2020-10-02 15:23 ` [PATCH v2 3/3] i2c: imx: Don't generate STOP condition if arbitration has been lost Christian Eggers
2020-10-05  8:16   ` Krzysztof Kozlowski [this message]

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