linux-kernel - Re: [PATCH v3 0/5] rtc-at91rm9200: add shadow interrupt mask

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Message-ID: <51A68DC8.3090703@interlog.com>
Date:	Wed, 29 May 2013 19:22:48 -0400
From:	Douglas Gilbert <dgilbert@...erlog.com>
To:	Robert Nelson <robertcnelson@...il.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Johan Hovold <jhovold@...il.com>,
	Robert Nelson <Robert.Nelson@...ikey.com>,
	Nicolas Ferre <nicolas.ferre@...el.com>,
	linux-kernel@...r.kernel.org,
	Ludovic Desroches <ludovic.desroches@...el.com>,
	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 0/5] rtc-at91rm9200: add shadow interrupt mask

On 13-05-29 04:41 PM, Robert Nelson wrote:
> On Wed, May 29, 2013 at 3:33 PM, Andrew Morton
> <akpm@...ux-foundation.org> wrote:
>> On Thu, 23 May 2013 10:38:50 +0200 Johan Hovold <jhovold@...il.com> wrote:
>>
>>> This is an update of the shadow-interrupt-mask series against v3.10-rc2.
>>>
>>> I guess we need Atmel to confirm that all sam9x5 SoCs are indeed
>>> affected. If not, then some probing mechanism as the one Doug suggested
>>> could be implemented on top of (a subset of) these patches. What do you
>>> say, Nicolas?
>>>
>>> Note that the first patch (adding a missing OF compile guard) could be
>>> applied straight away.
>>
>> At this stage it is unclear to me how to proceed with patches 2-5.
>
> fyi:
>
> A version of these patches had been applied once before:
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=0ef1594c017521ea89278e80fe3f80dafb17abde
>
> But due to a few issues it was later reverted:
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=e24b0bfa2f0446ffaad2661040be23668133aef8

Strange life of a patch. Mine was the original, Johan Hovold
objected and had it reverted. Johan then presented his first
patch then v2. They got lost in the weeds.

My hardware was still broken and this bug caused collateral
damage. My original patch no longer applied to lk 3.10.0-rc1
so I rewrote it, borrowing some of Johan's ideas and doing a
probe time check for the broken RTC_IMR. That patch was
presented about a week ago:
   http://marc.info/?l=linux-arm-kernel&m=136917492531478&w=2
The top of that post gives some more background.

That prompted Johan to produce v3 of his patch which is the
subject of this thread. I was hoping that Nicolas Ferre would
comment or ack one of these patches. Still waiting.


I have a copy of the original, publicly released manual for
the at91sam9g25 (a member of the at91sam9x5 family) marked
"11032A–ATARM–27-Jul-11". It contains the following:
   Errata
   49.3.1
     RTC: Interrupt Mask Register cannot be used
          Interrupt Mask Register reading always returns 0.

Both Rev B and Rev C of that manual drop that particular
erratum. My g25 SoC-based subsystems come from an Atmel
partner and still have the RTC IMR bug.

Doug Gilbert


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