From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ray Jui <rjui-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
Subject: Re: [PATCH v4 2/3] i2c: iproc: Add Broadcom iProc I2C Driver
Date: Sat, 17 Jan 2015 16:30:33 -0800
Message-ID: <54BAFEA9.9040900@broadcom.com>
References: <1421274213-3544-1-git-send-email-rjui@broadcom.com> <1421274213-3544-3-git-send-email-rjui@broadcom.com> <20150115084119.GN22880@pengutronix.de> <54B98C18.4080807@broadcom.com> <20150117160113.GA22880@pengutronix.de> <54BABEE9.8070801@broadcom.com> <20150117201849.GC22880@pengutronix.de> <54BACB66.6040909@broadcom.com> <20150117211017.GD22880@pengutronix.de> <54BAD391.9080909@broadcom.com> <20150117224021.GA26493@n2100.arm.linux.org.uk>
Mime-Version: 1.0
Content-Type: text/plain; charset="windows-1252"
Content-Transfer-Encoding: 7bit
Return-path: <linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
In-Reply-To: <20150117224021.GA26493-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
To: Russell King - ARM Linux <linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>
Cc: =?windows-1252?Q?Uwe_Kleine-K=F6nig?= <u.kleine-koenig-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>, Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>, Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Pawel Moll <pawel.moll-5wv7dgnIgG8@public.gmane.org>, Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>, Ian Campbell <ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org>, Kumar Gala <galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>, Grant Likely <grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>, Christian Daudt <bcm-xK7y4jjYLqYh9ZMKESR00Q@public.gmane.org>, Matt Porter <mporter-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>, Florian Fainelli <f.fainelli-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Scott Branden <sbranden-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>, linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, bcm-kernel-feedback-list-dY08KVG/lbpWk0Htik3J/w@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
List-Id: devicetree@vger.kernel.org



On 1/17/2015 2:40 PM, Russell King - ARM Linux wrote:
> On Sat, Jan 17, 2015 at 01:26:41PM -0800, Ray Jui wrote:
>> 	time_left = wait_for_completion_timeout(&iproc_i2c->done, time_left);
>>
>> 	/* disable all interrupts */
>> 	writel(0, iproc_i2c->base + IE_OFFSET);
>>
>> 	if (!time_left && !atomic_read(&iproc_i2c->transfer_is_successful)) {
> 
> Why are you using atomic_read() here?
> 
transfer_is_successful 1) will be reset to 0 in this function (before
kick start the I2C transfer), 2) will be set to 1 in the ISR (to signal
completion of the I2C transfer), and 3) will be checked in this function
here. I thought that means I should declare it volatile, because it can
be modified in both the process context and interrupt context (and I use
atomic because I remember Linux checkpatch warns against using volatile)?