From: robert.jarzmik@free•fr (Robert Jarzmik)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 2/4] rtc: sa1100: convert to run-time register mapping
Date: Fri, 06 Feb 2015 17:26:25 +0100 [thread overview]
Message-ID: <87vbjf80r2.fsf@free.fr> (raw)
In-Reply-To: <CAL_JsqJ5Ju98adz5Y2Ow2JDnvFdKhCRvpH8Xg1OfMYOhJaUUFw@mail.gmail.com> (Rob Herring's message of "Thu, 5 Feb 2015 14:47:43 -0600")
Rob Herring <robh@kernel•org> writes:
>> - adding to rtc-pxa driver :
>> - a new rtc device (ie. it will register 2 rtc devices, one of the sa1100
>> kind, one of the pxa specific kind)
>
> I fail to see what the rtc-pxa gets us? Something to do with which
> counter has correct time at boot? It has a rollover longer than ~126
> years is all I see. Otherwise, it looks like over-engineered h/w to
> me.
Compatibility with other OSes, for multi-OS boots, which is the main reason
rtc-pxa was developped. Of course the other OS is using the other registers,
*and* resets RCNR to 0 on boot.
>> This has flaws :
>> - a bit of code will be duplicated between rtc-pxa and rtc-sa1100
>
> That can probably be mitigated with a common file of shared functions.
Oh yeah, I like that. Would it mean that in the future you'd have time to help
with that task ?
>> - the ordering in rtc-pxa between the 2 rtc devices will be important, as if I
>> remember correctly /dev/rtc points to the first /dev/rtc0 registered
>>
>> But it opens up :
>> - DT path to both drivers
>> - isolation between sa1100 architecture changes and pxa architecture changes
>> - Rob's current patches can remain almost the same
>>
>>> Also note that by including the resource in rtc-sa1100's platform
>>> device resource list, you'll have stacked resources between the two
>>> platform devices appearing in /proc/iomem (you did look at that
>>> before posting the patches, right?)
>> I must admit I don't know if there are nasty consequences, I think I need to
>> follow up the code to have a clear idea.
>
> I don't follow either. The resources don't appear unless requested and
> we only have 1 driver requesting it.
There's only one small test to do to understand, as soon as I'm finished with my
zylonite's ethernet interrupts, I will make the test to understand what Russell
said, I might learn something in the test :)
Cheers.
--
Robert
next prev parent reply other threads:[~2015-02-06 16:26 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-03 23:22 [PATCH 0/4] SA1100 RTC clean-up for ARM64 Rob Herring
2015-02-03 23:22 ` [PATCH 1/4] ARM: pxa: add memory resource to RTC device Rob Herring
2015-02-03 23:22 ` [PATCH 2/4] rtc: sa1100: convert to run-time register mapping Rob Herring
2015-02-04 13:25 ` Arnd Bergmann
2015-02-04 13:44 ` Rob Herring
2015-02-04 13:49 ` Rob Herring
2015-02-04 14:24 ` Arnd Bergmann
2015-02-04 17:30 ` Robert Jarzmik
2015-02-05 13:34 ` Rob Herring
2015-02-05 13:50 ` Russell King - ARM Linux
2015-02-05 19:18 ` Robert Jarzmik
2015-02-05 20:47 ` Rob Herring
2015-02-06 16:26 ` Robert Jarzmik [this message]
2015-02-05 23:37 ` Russell King - ARM Linux
2015-02-06 16:20 ` =Robert Jarzmik
2015-02-14 12:22 ` Robert Jarzmik
2015-02-03 23:22 ` [PATCH 3/4] ARM: sa1100: remove unused RTC register definitions Rob Herring
2015-02-03 23:22 ` [PATCH 4/4] ARM: mmp: " Rob Herring
2015-02-04 10:44 ` [PATCH 0/4] SA1100 RTC clean-up for ARM64 Russell King - ARM Linux
2015-02-04 13:58 ` Rob Herring
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