From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1i7FLb-0001Ke-Mg for barebox@lists.infradead.org; Mon, 09 Sep 2019 08:48:34 +0000 Date: Mon, 9 Sep 2019 10:48:30 +0200 From: Sascha Hauer Message-ID: <20190909084830.5fxgs7oihsecquhm@pengutronix.de> References: <20190908000314.27078-1-andrew.smirnov@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190908000314.27078-1-andrew.smirnov@gmail.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [PATCH] i2c/pca954x: Initialize the mux to disconnected state To: Andrey Smirnov Cc: barebox@lists.infradead.org On Sat, Sep 07, 2019 at 05:03:14PM -0700, Andrey Smirnov wrote: > Port of a Linux kernel commit cd823db8b1161ef0d756514d280715a576d65cc3 > > pca954x power-on default is channel 0 connected. If multiple pca954x > muxes are connected to the same physical I2C bus, the parent bus will > see channel 0 devices behind both muxes by default. This is bad. > > Scenario: > -- pca954x @ 0x70 -- ch 0 (I2C-bus-101) -- EEPROM @ 0x50 > | > I2C-bus-1 --- > | > -- pca954x @ 0x71 -- ch 0 (I2C-bus-111) -- EEPROM @ 0x50 > > 1. Load I2C bus driver: creates I2C-bus-1 > 2. Load pca954x driver: creates virtual I2C-bus-101 and I2C-bus-111 > 3. Load eeprom driver > 4. Try to read EEPROM @ 0x50 on I2C-bus-101. The transaction will also bleed > onto I2C-bus-111 because pca954x @ 0x71 channel 0 is connected by default. > > Fix: Initialize pca954x to disconnected state in pca954x_probe() > > Signed-off-by: Petri Gynther > Signed-off-by: Jean Delvare > Cc: stable@kernel.org > > Signed-off-by: Andrey Smirnov > --- > drivers/i2c/muxes/i2c-mux-pca954x.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) Applied with whitespace cleanup, thanks Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox