linux-kernel - Re: [PATCH 1/4] rtc: sa1100: enable/disable rtc when probe/remove the device

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 4 Dec 2012 15:01:39 +0800
From:	Haojian Zhuang <haojian.zhuang@...il.com>
To:	Chao Xie <xiechao.mail@...il.com>
Cc:	Russell King - ARM Linux <linux@....linux.org.uk>,
	Chao Xie <chao.xie@...vell.com>,
	Alessandro Zummo <a.zummo@...ertech.it>,
	"rtc-linux@...glegroups.com" <rtc-linux@...glegroups.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 1/4] rtc: sa1100: enable/disable rtc when probe/remove the device

On Tuesday, December 4, 2012, Chao Xie wrote:
>
> On Mon, Dec 3, 2012 at 5:48 PM, Russell King - ARM Linux
> <linux@....linux.org.uk> wrote:
> > On Mon, Dec 03, 2012 at 10:53:07AM +0800, Chao Xie wrote:
> >> I want to correct what i said. For the irq register/unregister i think
> >> can be done at open/release. But for clock enable/disable, i do not
> >> think so. If clock is disabled, as i think RTC will not work. User API
> >> still use open->get_time->close for "date" command. It means that RTC
> >> will not return correct date to user.
> >
> > "I think" is not good enough for patches like this.  Please test it.
> >
> > On SA11x0 and PXA platforms, the clock for the sa1100-rtc is a dummy
> > clock; it has no effect.  For MMP, I don't have access to the TRMs so
> > that's something you're going to have to find out.
>
> I tested at pxa910 which uses rtc-sa1100 as driver.
> the test procedure is simple
> open->ioctl(RTC_RD_TIME)->close
> With the original code, the rtc will not update, i always get the same value
>
> remove clock disable/enable in release/open, and enable/disable clock
> at probe/remove.
> the rtc can update, and i can read the correct rtc value.

Yes, clock shouldn't be controlled in open/close. Otherwise, RTC can't
work since
clock is already gated. I didn't find the issue since there're two RTC
enabled in my
board. The default one impacts the test.

I think that you need send the patch that only move clock operation
into probe().
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/