linux-kernel - Re: [PATCH 1/3] clocksource: defbool CLKSRC_QCOM=y on ARCH

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Message-ID: <5655B62D.6090309@linaro.org>
Date:	Wed, 25 Nov 2015 14:22:53 +0100
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	linux-arm-kernel@...ts.infradead.org,
	Stephen Boyd <sboyd@...eaurora.org>,
	linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Andy Gross <agross@...eaurora.org>
Subject: Re: [PATCH 1/3] clocksource: defbool CLKSRC_QCOM=y on ARCH_QCOM and
 make it visible

On 11/25/2015 01:49 PM, Arnd Bergmann wrote:
> On Wednesday 25 November 2015 13:37:53 Daniel Lezcano wrote:
>> On 11/25/2015 11:17 AM, Arnd Bergmann wrote:
>>> On Wednesday 25 November 2015 11:10:49 Daniel Lezcano wrote:
>>>> On 11/25/2015 02:08 AM, Stephen Boyd wrote:
>>>>> We want to remove the ARCH_MSM* configs in mach-qcom/Kconfig
>>>>> because they are mostly proxy configs for selecting the right
>>>>> clocksource driver. Therefore, make CLKSRC_QCOM default to the
>>>>> value of ARCH_QCOM, but also make it visible if ARCH_QCOM=y so
>>>>> that we can turn it off when we don't want it.
>>>>
>>>> I have been removing the ARCH dependencies in the Kconfig file.
>>>>
>>>> Why do you have to turn it off manually ?
>>>
>>> The background is that this is used only on some of the older
>>> MSM SoCs, while the newer ones use the arch timer.
>>>
>>> We decided to remove the SoC-specific top-level options from
>>> mach-msm as they are becoming rather meaningless these days
>>> and just a burden to maintain at the rate that new variants
>>> get released, so being able to turn off this driver helps make
>>> the kernel slightly smaller if you are building a kernel for
>>> only the more recent models.
>>
>> Ok, thanks for the clarification.
>>
>> I don't really like this approach even if it is correct because it
>> breaks the current approach I am trying to make consistent across the
>> drivers.
>>
>> I would like to have the COMPILE_TEST option available for all the
>> drivers and move this option under the menu config. This patch will
>> prevent to do this code factoring.
>
> How about moving the option to arch/arm/mach-qcom/Kconfig then?
>
> We could have a user-selectable "allow use of qcom clocksource"
> option there, which would then select the driver.

Yes, why not.

>> On the other side, this option is supposed to have a slightly smaller
>> kernel when it is not used. But when does it happen ? When
>> ARCH_MSM8X60=n and ARCH_MSM8960=n. With this patchset, I don't see the
>> ability to turn these SoCs off as the options are removed. So the
>> associated code is not removed, right ?
>>
>> So why allow to turn off the timer but disallow that for the entire SoC ?
>
> The timer is the only code that is controlled by those two options at
> the moment, all the other differences between SoCs are already handled
> by enabling the respective device drivers.

Ok, I see.

Thanks.

   -- Daniel


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