From: grinberg@compulab•co.il (Igor Grinberg)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] ARM: OMAP2+: timer: remove CONFIG_OMAP_32K_TIMER
Date: Mon, 12 Nov 2012 09:24:59 +0200 [thread overview]
Message-ID: <50A0A44B.6080604@compulab.co.il> (raw)
In-Reply-To: <79CD15C6BA57404B839C016229A409A83EB70E88@DBDE01.ent.ti.com>
On 11/12/12 08:38, Hiremath, Vaibhav wrote:
> On Sun, Nov 11, 2012 at 17:05:07, Igor Grinberg wrote:
>>
>>
>> On 11/08/12 20:34, Jon Hunter wrote:
>>>
>>> On 11/08/2012 12:17 PM, Paul Walmsley wrote:
>>>> On Thu, 8 Nov 2012, Jon Hunter wrote:
>>>>
>>>>> On 11/08/2012 11:58 AM, Paul Walmsley wrote:
>>>>>> On Thu, 8 Nov 2012, Jon Hunter wrote:
>>>>>>
>>>>>>> Igor was mentioning a h/w scenario where the 32kHz source is not
>>>>>>> present. However, I am not sure which devices support this and is
>>>>>>> applicable too.
>>>>>>
>>>>>> Pretty sure Igor is referring to the AM3517/3505. This is very poorly
>>>>>> documented, but can be observed in the AM3517 TRM Rev B (SPRUGR0B) Figure
>>>>>> 4-23 "PRM Clock Generator" and the AM3517 DM Rev C (SPRS550C) Section 4
>>>>>> "Clock Specifications".
>>>>>
>>>>> But AFAICT, even in that h/w configuration the internal 32k
>>>>> oscillator will be used
>>>>
>>>> Just to clarify, there's no internal 32k oscillator used on the 3517/3505;
>>>> just a divider from the HF clock.
>>>
>>> Ah yes I see that now!
>>>
>>>>> and so the gptimer will still have a 32k clock source.
>>>>
>>>> That's a good question and you might want to check with Igor on that one,
>>>> the AM3517 TRM conflicts with the DM as to whether it's available to the
>>>> GPTIMER or not :-(
>>>
>>> Well the external 32k and internal divided down version go through the
>>> same mux and so that seems to imply either they are both available to
>>> the gptimer or neither is.
>>
>> Yep, but the /800 do not get you the 32768...
>> and that makes the timer suck.
>> Of course this can be dealt with in the clock subsystem
>> (I remember Paul said that he will look into that), but it will take time.
>>
>> Also, what about having the sys_clk instead of 32k for higher precision?
>> Is that possible already (without my patch)?
>>
>
> Yes, it is possible. You can choose it through bootargs.
Is the kernel command line the only way for doing this?
I personally dislike it, because it brings multiple maintenance problems.
This must be possible at least through DT.
--
Regards,
Igor.
next prev parent reply other threads:[~2012-11-12 7:24 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-07 14:42 [PATCH] ARM: OMAP2+: timer: remove CONFIG_OMAP_32K_TIMER Igor Grinberg
2012-11-07 17:33 ` Tony Lindgren
2012-11-08 7:13 ` Igor Grinberg
2012-11-08 16:20 ` Tony Lindgren
2012-11-08 17:09 ` Hiremath, Vaibhav
2012-11-11 9:16 ` Igor Grinberg
2012-11-12 19:05 ` Jon Hunter
2012-11-13 9:08 ` Igor Grinberg
2012-11-12 22:06 ` Tony Lindgren
2012-11-07 21:36 ` Jon Hunter
2012-11-08 7:59 ` Igor Grinberg
2012-11-08 16:16 ` Jon Hunter
2012-11-08 17:08 ` Hiremath, Vaibhav
2012-11-08 17:39 ` Jon Hunter
2012-11-08 17:47 ` Hiremath, Vaibhav
2012-11-08 17:58 ` Jon Hunter
2012-11-08 18:06 ` Hiremath, Vaibhav
2012-11-08 18:13 ` Jon Hunter
2012-11-08 18:28 ` Hiremath, Vaibhav
2012-11-08 18:47 ` Jon Hunter
2012-11-09 0:55 ` Jon Hunter
2012-11-12 6:42 ` Hiremath, Vaibhav
2012-11-08 17:58 ` Paul Walmsley
2012-11-08 18:08 ` Jon Hunter
2012-11-08 18:17 ` Paul Walmsley
2012-11-08 18:34 ` Jon Hunter
2012-11-11 11:35 ` Igor Grinberg
2012-11-12 6:38 ` Hiremath, Vaibhav
2012-11-12 7:24 ` Igor Grinberg [this message]
2012-11-12 10:40 ` Hiremath, Vaibhav
2012-12-10 20:49 ` Paul Walmsley
2012-12-14 23:58 ` Russ Dill
2012-11-11 11:25 ` Igor Grinberg
2012-11-08 18:54 ` Jon Hunter
2012-11-08 18:59 ` Hiremath, Vaibhav
2012-11-08 19:16 ` Jon Hunter
2012-11-11 11:28 ` Igor Grinberg
2012-11-12 19:15 ` Jon Hunter
2012-11-13 9:14 ` Igor Grinberg
2012-11-13 16:13 ` Jon Hunter
2012-11-14 7:23 ` Igor Grinberg
2012-11-12 10:38 ` Hiremath, Vaibhav
2012-11-12 11:01 ` Benoit Cousson
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