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Re: [PATCH v2 02/16] arm64: dts: add sp804 timer node for Hi6220

From Linus Walleij <linus.walleij@linaro.org>
Newsgroups linux.kernel
Subject Re: [PATCH v2 02/16] arm64: dts: add sp804 timer node for Hi6220
Date 2016-04-04 13:30 +0200
Message-ID <rkaRH-2fN-3@gated-at.bofh.it> (permalink)
References <rjqc9-1I3-3@gated-at.bofh.it> <rjqc9-1I3-13@gated-at.bofh.it> <rjVSF-8av-5@gated-at.bofh.it> <rk1Op-3S6-3@gated-at.bofh.it>
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On Mon, Apr 4, 2016 at 3:43 AM, Leo Yan <leo.yan@linaro.org> wrote:
> On Sun, Apr 03, 2016 at 09:23:42PM +0200, Linus Walleij wrote:
>> On Sat, Apr 2, 2016 at 11:29 AM, Guodong Xu <guodong.xu@linaro.org> wrote:

>> By chance the code in the driver will allow just one clock and
>> will then assume that both the bus to the timer and the timer
>> itself is clocked from the same clock. But I highly doubt that this
>> is the case.
>
> This patch has been sent out for review previously [1]; So I refered
> other platforms and changed to only enable apb bus clock due I have
> not found timer enabling bits in Hi6220's spec.

This is not about enabling/disabling the clock(s) to the timer.
It doesn't matter if these clocks are always on.

It is about determining the *frequency* of the timers.

It is vital that the timer driver get the right frequency of the clock
to the block from the clock implementation, and I do not think
it is the same as the "apb_pclk".

The thing is that of course "any frequency" will
work but what you will notice is that the timer runs very
weirdly compared to wall-clock time unless the right clock
yielding the right frequency has been specified here.

Yours,
Linus Walleij

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Thread

Re: [PATCH v2 02/16] arm64: dts: add sp804 timer node for Hi6220 Linus Walleij <linus.walleij@linaro.org> - 2016-04-03 21:30 +0200
  Re: [PATCH v2 02/16] arm64: dts: add sp804 timer node for Hi6220 Leo Yan <leo.yan@linaro.org> - 2016-04-04 03:50 +0200
    Re: [PATCH v2 02/16] arm64: dts: add sp804 timer node for Hi6220 Linus Walleij <linus.walleij@linaro.org> - 2016-04-04 13:30 +0200
      Re: [PATCH v2 02/16] arm64: dts: add sp804 timer node for Hi6220 Leo Yan <leo.yan@linaro.org> - 2016-04-04 15:50 +0200
        Re: [PATCH v2 02/16] arm64: dts: add sp804 timer node for Hi6220 Linus Walleij <linus.walleij@linaro.org> - 2016-04-04 16:00 +0200
          Re: [PATCH v2 02/16] arm64: dts: add sp804 timer node for Hi6220 Leo Yan <leo.yan@linaro.org> - 2016-04-04 16:10 +0200
  Re: [PATCH v2 02/16] arm64: dts: add sp804 timer node for Hi6220 Rob Herring <robh@kernel.org> - 2016-04-04 07:20 +0200

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