linux-kernel - Re: [PATCH v3 4/5] i2c: davinci: use bus recovery infrastructure

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Date:	Wed, 18 Mar 2015 21:31:51 +0100
From:	Wolfram Sang <wsa@...-dreams.de>
To:	Grygorii Strashko <grygorii.strashko@...com>
Cc:	Sekhar Nori <nsekhar@...com>,
	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>, linux-i2c@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Kevin Hilman <khilman@...prootsystems.com>,
	Santosh Shilimkar <ssantosh@...nel.org>,
	Murali Karicheri <m-karicheri2@...com>
Subject: Re: [PATCH v3 4/5] i2c: davinci: use bus recovery infrastructure

Hi,

so, the bus recovery patches look fine to me in general.

It is only this one question left which I always had with bus recovery.
Maybe you guys can join me thinking about it.

> @@ -376,8 +366,7 @@ i2c_davinci_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, int stop)
>  						      dev->adapter.timeout);
>  	if (r == 0) {
>  		dev_err(dev->dev, "controller timed out\n");
> -		davinci_i2c_recover_bus(dev);
> -		i2c_davinci_init(dev);
> +		i2c_recover_bus(adap);
>  		dev->buf_len = 0;
>  		return -ETIMEDOUT;

The I2C specs say in 3.1.16 that the recovery procedure should be used
when SDA is stuck low. So, I do wonder if we should apply the recovery
after a timeout. Stuck SDA might be one reason for timeout, but there
may be others...

Thanks,

   Wolfram


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