Message-ID: <4C1F0FC7.60605@pengutronix.de>
Date: Mon, 21 Jun 2010 09:07:51 +0200
From: Marc Kleine-Budde <mkl@pengutronix.de>
Organization: Pengutronix
User-Agent: Thunderbird 2.0.0.24 (X11/20100317)
MIME-Version: 1.0
To: Ben Dooks <ben-linux@fluff.org>
CC: Sascha Hauer <sha@pengutronix.de>, linux-i2c@vger.kernel.org,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH V2] i2c-imx: do not allow interruptions when waiting for
 I2C to complete (resend)
References: <4C1753F6.3080106@pengutronix.de> <20100620223321.GA12387@fluff.org.uk>
In-Reply-To: <20100620223321.GA12387@fluff.org.uk>
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Ben Dooks wrote:
> On Tue, Jun 15, 2010 at 12:20:38PM +0200, Marc Kleine-Budde wrote:
>> The i2c_imx_trx_complete() function is using
>> wait_event_interruptible_timeout() to wait for the I2C controller to
>> signal that it has completed an I2C bus operation. If the process that=

>> causes the I2C operation receives a signal, the wait will be
>> interrupted, returning an error. It is better to let the I2C operation=

>> finished before handling the signal (i.e. returning into userspace).
>>
>> It is safe to use wait_event_timeout() instead, because the timeout
>> will allow the process to exit if the I2C bus hangs. It's also better
>> to allow the I2C operation to finish, because unacknowledged I2C
>> operations can cause the I2C bus to hang.
>=20
> Hmm, if it times out, do you need to at-least try sending a stop
> on the bus? or does the caller do that for you?

The caller of the caller does this. "i2c_imx_xfer" will call
"i2c_imx_stop", and this function will generate the stop condition if
not already done so.

I'm sending a V3 version of the patch, which removes the only written to
variable "result".

cheers, Marc

--=20
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |


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