linux-kernel - Re: [PATCH v2] Add suspend/resume for HPET

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Message-ID: <20070329175117.GA5521@elte.hu>
Date:	Thu, 29 Mar 2007 19:51:17 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Maxim Levitsky <maximlevitsky@...il.com>,
	Sergei Shtylyov <sshtylyov@...mvista.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jeff Chua <jeff.chua.linux@...il.com>,
	Adrian Bunk <bunk@...sta.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>, pavel@...e.cz,
	linux-pm@...ts.osdl.org, gregkh@...e.de,
	linux-pci@...ey.karlin.mff.cuni.cz,
	Jens Axboe <jens.axboe@...cle.com>,
	Len Brown <lenb@...nel.org>, linux-acpi@...r.kernel.org,
	jgarzik@...ox.com, linux-ide@...r.kernel.org,
	"Michael S. Tsirkin" <mst@...lanox.co.il>
Subject: Re: [PATCH v2] Add suspend/resume for HPET


* Linus Torvalds <torvalds@...ux-foundation.org> wrote:

> Btw, what about arch/x86_64/kernel/hpet.c?

at least wrt. suspend/resume it should be fine, because in 
arch/x86_64/kernel/time.c it does this upon resume:

 static int timer_resume(struct sys_device *dev)
 {
         if (hpet_address)
                 hpet_reenable();
         else
                 i8254_timer_resume();

[ barring the issue that mixing two pieces of hardware like this in a 
  single resume function is wrong - all timer hardware should be 
  separated like we did it for i386. I've got 64-bit clockevents code in 
  -rt which does this separation. ]

> That thing seems totally broken. Lookie here:
> 
>   arch/x86_64/kernel/hpet.c:irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id, struct pt_regs *regs)
>   drivers/char/rtc.c:extern irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id);
> 
> anybody see a problem? The x86-64 version doesn't seem to be very well 
> maintained. Is there some fundamental reason why this file isn't 
> shared across architectures?

there's no fundamental reason. x86_64 COW-ed hpet_timer.c and 
time_hpet.c years ago and drifted off into different areas.
They should be unified: more power to arch/x86/ ;-)

	Ingo
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