linux-kernel - Re: [PATCH] i2c: algo-pca: Add 0x78 as SCL stuck low status

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Message-ID: <20200623193413.GB1203@ninjato>
Date:   Tue, 23 Jun 2020 21:34:13 +0200
From:   Wolfram Sang <wsa@...nel.org>
To:     Chris Packham <chris.packham@...iedtelesis.co.nz>
Cc:     andriy.shevchenko@...ux.intel.com, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] i2c: algo-pca: Add 0x78 as SCL stuck low status

Hi Chris,

thanks for the patch!

On Mon, Jun 22, 2020 at 10:57:05AM +1200, Chris Packham wrote:
> The PCA9665 datasheet says that I2CSTA = 78h indicates that SCL is stuck
> low, this differs to the PCA9564 which uses 90h for this indication.
> Treat either 0x78 or 0x90 as an indication that the SCL line is stuck.
> 
> Signed-off-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
> ---
> Based on looking through the PCA9564 and PCA9665 datasheets this should be
> safe. The PCA9564 should not return 0x78 for any valid state and the PCA9665
> should not return 0x90.

On the other hand, we know which type was detected, so we could check
for the correct type?

Kind regards,

   Wolfram


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