linux-kernel - Re: [PATCH] clocksource: arch_timer: Fix arm64 platforms not booting

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Date:	Mon, 29 Dec 2014 21:54:33 +0100
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	Mark Rutland <mark.rutland@....com>,
	Christoffer Dall <christoffer.dall@...aro.org>, arnd@...db.de
CC:	Marc Zyngier <Marc.Zyngier@....com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Catalin Marinas <Catalin.Marinas@....com>,
	Olof Johansson <olof@...om.net>,
	Yingjoe Chen <yingjoe.chen@...iatek.com>,
	Sonny Rao <sonnyrao@...omium.org>
Subject: Re: [PATCH] clocksource: arch_timer: Fix arm64 platforms not booting

On 12/29/2014 08:13 PM, Mark Rutland wrote:
> [Adding Arnd]
>
> On Mon, Dec 29, 2014 at 08:35:09AM +0000, Christoffer Dall wrote:
>> On Sun, Dec 28, 2014 at 09:46:20PM +0000, Marc Zyngier wrote:
>>> On 2014-12-28 14:20, Christoffer Dall wrote:
>>>> Commit 0b46b8a718c6e ("clocksource: arch_timer: Fix code to...")
>>>> fixes
>>>> timer issues with certain ARMv7 platforms, but unfortunately breaks
>>>> arm64 platforms with hyp mode (EL2) enabled.
>>>>
>>>> The commit only sets arch_timer_use_virtual to false under
>>>> CONFIG_ARM,
>>>> but forgets that the config variable is also set in other code paths
>>>> (actually, right underneath the check in the patch) with detrimental
>>>> consequences as we've now introduced a direct early call to BUG() on
>>>> practically all arm64 platforms.
>>>>
>>>> One could argue that this code could be refactored to use different
>>>> variables for checking which *timer* to use and which *counter* to
>>>> use,
>>>> which seems to be the desired difference between ARM and arm64 in
>>>> this
>>>> case, but this approach fixes an urgent issue for now.
>>>>
>>>> Cc: Sonny Rao <sonnyrao@...omium.org>
>>>> Cc: Catalin Marinas <catalin.marinas@....com>
>>>> Cc: Daniel Lezcano <daniel.lezcano@...aro.org>
>>>> Cc: Olof Johansson <olof@...om.net>
>>>> Cc: Mark Rutland <mark.rutland@....com>
>>>> Cc: Catalin Marinas <catalin.marinas@....com>
>>>> Cc: Marc Zyngier <marc.zyngier@....com>
>>>> Cc: Yingjoe Chen <yingjoe.chen@...iatek.com>
>>>> Signed-off-by: Christoffer Dall <christoffer.dall@...aro.org>
>>>> ---
>>>> This was apparently already discovered by Yingjoe Chen in this thread
>>>> https://lkml.org/lkml/2014/11/24/41 and Catalin recommended a similar
>>>> fix.
>>>
>>> I'm increasingly worried about the time it takes to get such critical
>>> fixes into the tree (arm64 is *dead* without it).
>>>
>>> What is holding this patch which, as far as I remember, has been posted
>>> by Catalin almost three weeks ago?
>>>
>> I didn't find that since I didn't think I'd have to go back that long on
>> lakml for something that breaks boot of an entire architecture.  Sorry
>> for the confusion of a second patch, but fwiw, I now spent another few
>> hours bisecting this, so I would really like to see this fix go into
>> mainline ASAP as well to save others the trouble.
>
> Last I knew, Arnd was going to take the fix [1], which has been in
> arm-soc's for-next and fixes branches for almost two weeks now. It
> didn't make it into the last pull req due to some confusion over who was
> going to take it.

I asked arm-soc team to take the fix because it was depending on a patch 
which was already in their tree [1].

Merry Christmas

   -- Daniel

[1] http://www.spinics.net/lists/arm-kernel/msg385704.html

> Arnd, what's the plan for getting this into mainline ASAP?
>
> Mark.
>
> [1] https://git.kernel.org/cgit/linux/kernel/git/arm/arm-soc.git/commit/?h=fixes&id=d6ad36913083d683aad4e02e53580c995f1a6ede
>


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