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From: haojian.zhuang@linaro.org (Haojian Zhuang)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v3 06/11] ARM: vexpress: use clocksource_of_init for sp804
Date: Wed, 13 Mar 2013 23:01:40 +0800
Message-ID: <CAD6h2NRkS4qk+iqbWhaOpBHmjSYOB=YBbfNkn0X3jzNawzgNEA@mail.gmail.com> (raw)
In-Reply-To: <1363186087.3100.72.camel@hornet>

On 13 March 2013 22:48, Pawel Moll <pawel.moll@arm.com> wrote:
> On Wed, 2013-03-13 at 12:21 +0000, Haojian Zhuang wrote:
>> Do you mean that system wants to pick any one randomly? It's impossible.
>
> It is possible in case of the VE platform. Therefore it is not
> completely impossible. QED :-)
>
Yes, it's possible. Since only clocksource / clockevent is using SP804 timer
on the VE platform. If user app or something else is using other SP804
timer, it would be mess because of resource conflict.

>> Imagine that only TIMINT1 signal in sp804 is routed to interrupt controller.
>> Could system still pick any one it wants?
>
Then we need another new property. I try to find using minim properties.

> If you tell the system that only TIMINT1 is wired, it shouldn't even try
> to use the second timer for anything that would require the interrupt.
> Therefore, describing the hardware sufficiently, you're giving the
> system enough information to make the right decisions.
>
>> I think that clocksource or clockevent must be specified in DTS. Whatever
>> we're using alias or property.
>
> I'm convinced it does not *must* be there. I think it *can* be there,
> for platforms where the available timers are not equal (for whatever
> reason). My point is: why are you trying to force me to put some
> information into my hardware description which doesn't have any meaning
> for me?
>
As I mentioned above, system must know the behavior first. The upper layer
software could know which timer is used in clocksource or clockevent.

For example, your Android system could be shared on multiple platforms. It
could parse hardware information from DTS. (Of course, it hasn't this feature
yet). Then it could arrange apps to use other timers.

It's like you define console on specified UART even you have multiples UART
port.

  reply index

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-03-13  5:05 [PATCH v3 00/11] add hisilicon SoC support Haojian Zhuang
2013-03-13  5:05 ` [PATCH v3 01/11] clocksource: move sp timer driver Haojian Zhuang
2013-03-13  5:05 ` [PATCH v3 02/11] clocksource: select USE_OF by default Haojian Zhuang
2013-03-13  5:05 ` [PATCH v3 03/11] clocksource: sp804: add device tree support Haojian Zhuang
2013-03-13 11:05   ` Pawel Moll
2013-03-13 11:37     ` Haojian Zhuang
2013-03-13 11:41       ` Pawel Moll
2013-03-13 14:17     ` Rob Herring
2013-03-13 14:42       ` Pawel Moll
2013-03-13 14:51         ` Rob Herring
2013-03-13 14:55           ` Pawel Moll
2013-03-13 15:11             ` Haojian Zhuang
2013-03-13 15:23               ` Pawel Moll
2013-03-13 15:25                 ` Haojian Zhuang
2013-03-13 15:29                   ` Pawel Moll
2013-03-13 15:39                     ` Rob Herring
2013-03-13 15:41                       ` Pawel Moll
2013-03-13 15:44                         ` Haojian Zhuang
2013-03-13 15:42                     ` Haojian Zhuang
2013-03-13 15:49                       ` Pawel Moll
2013-03-13 16:35                         ` Arnd Bergmann
2013-03-13 16:41                           ` Pawel Moll
2013-03-15 12:20       ` Russell King - ARM Linux
2013-03-13  5:05 ` [PATCH v3 04/11] ARM: integrator: use clocksource_of_init for sp804 Haojian Zhuang
2013-03-13  5:05 ` [PATCH v3 05/11] ARM: highbank: " Haojian Zhuang
2013-03-13  5:05 ` [PATCH v3 06/11] ARM: vexpress: " Haojian Zhuang
2013-03-13 11:10   ` Pawel Moll
2013-03-13 11:42     ` Haojian Zhuang
2013-03-13 11:46       ` Pawel Moll
2013-03-13 12:21         ` Haojian Zhuang
2013-03-13 14:48           ` Pawel Moll
2013-03-13 15:01             ` Haojian Zhuang [this message]
2013-03-13 15:19               ` Pawel Moll
2013-03-13 15:59                 ` Haojian Zhuang
2013-03-13 16:28                   ` Pawel Moll
2013-03-13 16:32                   ` Rob Herring
2013-03-15 12:34                     ` Russell King - ARM Linux
2013-03-15 12:58                       ` Pawel Moll
2013-03-15 18:10                         ` Russell King - ARM Linux
2013-03-13  5:05 ` [PATCH v3 07/11] ARM: debug: support debug ll on hisilicon soc Haojian Zhuang
2013-03-13  5:05 ` [PATCH v3 08/11] clk: hi3xxx: add clock support Haojian Zhuang
2013-03-13  5:05 ` [PATCH v3 09/11] ARM: hi3xxx: add board support with device tree Haojian Zhuang
2013-03-13  5:05 ` [PATCH v3 10/11] ARM: hi3xxx: enable hi4511 " Haojian Zhuang
2013-03-13  5:05 ` [PATCH v3 11/11] ARM: config: append arch hi3xxx into multi defconfig Haojian Zhuang

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