linux-kernel - Re: [PATCH] RTC: Fix for issues in the kernel RTC API.

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Date:	Thu, 3 Feb 2011 16:41:25 -0200
From:	Marcelo Roberto Jimenez <mroberto@...i.cetuc.puc-rio.br>
To:	john stultz <johnstul@...ibm.com>
Cc:	a.zummo@...ertech.it, rtc-linux@...glegroups.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] RTC: Fix for issues in the kernel RTC API.

Hi John,

On Wed, Feb 2, 2011 at 20:28, john stultz <johnstul@...ibm.com> wrote:
> On Wed, 2011-02-02 at 14:24 -0800, John Stultz wrote:
>> On Wed, 2011-02-02 at 15:58 -0200, Marcelo Roberto Jimenez wrote:
>> > Again, what the rtc-test kernel RTC and the strongarm RTC user space
>> > behavior have changed. Alarm interrupts and update interrupts were
>> > generated by a different interrupts in the strongarm driver, and the
>> > rtc-test driver also behaved similarly, i.e., an update interrupt did
>> > not trigger an alarm interrupt. Currently, rtc_handle_legacy_irq()
>> > centralizes the irq processing, and by not checking the generated
>> > interrupt, it allows the new behavior, which seemed broken to me.
>>
>> So
>
> Sorry. I didn't finish my thought here. (I *did not* mean "So?" :)
>
> So... yes, we should make sure its not broken. Could you explain some
> more details about the different interrupts fro the driver?  If the two
> interrupt types come from different sources, is there a problem actually
> using the alarm irq to emulate the update irq? In other words, can we
> just skip the update irq management code? Or is there a draw back to
> that?

In a real timer device, I don't see a problem, as time passes the same
for everything, including update and alarm interrupts. This is an
issue only in the rtc-test driver, which is just a debug device. Since
everything is now emulated in timers, the word IRQ does not make sense
anymore, the right thing to do would be a global rename to remove
references to that string in the RTC framework. The rtc-test driver is
based on the concept of an interrupt, which is no longer the case.

I think your implementation is fine.

> thanks
> -john

Regards,
Marcelo.
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