linux-kernel - Re: [PATCH v6 08/19] i2c: octeon: Enable High-Level Controller

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Message-ID: <20160421134053.GB2623@hardcore>
Date:	Thu, 21 Apr 2016 15:40:53 +0200
From:	Jan Glauber <jan.glauber@...iumnetworks.com>
To:	David Daney <ddaney@...iumnetworks.com>
CC:	Wolfram Sang <wsa@...-dreams.de>, <linux-kernel@...r.kernel.org>,
	<linux-i2c@...r.kernel.org>
Subject: Re: [PATCH v6 08/19] i2c: octeon: Enable High-Level Controller

On Wed, Apr 20, 2016 at 02:55:15PM -0700, David Daney wrote:
> On 04/20/2016 02:43 PM, Wolfram Sang wrote:
> >On Mon, Apr 11, 2016 at 05:28:39PM +0200, Jan Glauber wrote:
> [...]
> >>+ */
> >>+static int octeon_i2c_hlc_wait(struct octeon_i2c *i2c)
> >>+{
> >>+	int time_left;
> >>+
> >>+	octeon_i2c_hlc_int_enable(i2c);
> >>+	time_left = wait_event_interruptible_timeout(i2c->queue,
> >>+					octeon_i2c_hlc_test_ready(i2c),
> >>+					i2c->adap.timeout);
> >
> >Have you tested signal handling thoroughly? Most driver dropped the
> >_interruptible after a while. Mostly they found out that the state
> >machine of the interrupt handler couldn't gracefully deal with it and
> >nobody really needed the interruptible. Just saying.
> 
> Good point.  We know that exiting with a signal leaves us in an
> undefined state.
> 
> We will have to think on this point.

I think we should just drop the _interruptible_ and use
wait_event_timeout. The same is already used in the octeon_i2c_wait().
The 2ms timeout should not hurt anyone.

> >
> >>+	octeon_i2c_int_disable(i2c);
> >>+	if (!time_left) {
> >>+		octeon_i2c_hlc_int_clear(i2c);
> >>+		dev_dbg(i2c->dev, "%s: timeout\n", __func__);
> >>+		return -ETIMEDOUT;
> >>+	}
> >>+
> >>+	if (time_left < 0) {
> >>+		dev_dbg(i2c->dev, "%s: wait interrupted\n", __func__);
> >>+		return time_left;
> >>+	}
> >>+	return 0;
> >>+}
> >
> >Drop the debug messages?
> >
> >I can't say much about the HW details, of course. Didn't spot anything
> >suspicious there.
> >