From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753562AbbKCMBJ (ORCPT ); Tue, 3 Nov 2015 07:01:09 -0500 Received: from mail-pa0-f46.google.com ([209.85.220.46]:34379 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752330AbbKCMBI (ORCPT ); Tue, 3 Nov 2015 07:01:08 -0500 Subject: Re: [PATCH 20/22] clocksource/drivers/exynos_mct: Fix Kconfig and add COMPILE_TEST option To: Arnd Bergmann , Daniel Lezcano References: <1446469011-22710-1-git-send-email-daniel.lezcano@linaro.org> <563806E7.6010105@samsung.com> <563872E2.10001@linaro.org> <9713489.TbNNoNQg5A@wuerfel> Cc: k.kozlowski.k@gmail.com, tglx@linutronix.de, john.stultz@linaro.org, linux-kernel@vger.kernel.org, Russell King , Kukjin Kim , "moderated list:ARM SUB-ARCHITECT..." , "moderated list:ARM/SAMSUNG EXYNO..." From: Krzysztof Kozlowski X-Enigmail-Draft-Status: N1110 Message-ID: <5638A1FE.1000403@samsung.com> Date: Tue, 3 Nov 2015 21:01:02 +0900 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <9713489.TbNNoNQg5A@wuerfel> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org W dniu 03.11.2015 o 19:02, Arnd Bergmann pisze: > On Tuesday 03 November 2015 09:40:02 Daniel Lezcano wrote: >> On 11/03/2015 01:59 AM, Krzysztof Kozlowski wrote: >>> On 03.11.2015 09:30, Krzysztof Kozlowski wrote: >>>> On 02.11.2015 21:56, Daniel Lezcano wrote: >>>>> Let the platform's Kconfig to select the clock instead of having a reverse >>>>> dependency from the driver to the platform options. >>>> >>>> Selecting user-visible symbols is rather discouraged so why not >>>> something like this: >>>> >>>> - def_bool y if ARCH_EXYNOS >>>> - depends on !ARM64 >>>> + bool "Exynos multi core timer driver" >>>> + depends on ARCH_EXYNOS || (COMPILE_TEST && ARM) >>> >>> Nope, that was wrong as we loose auto-select on Exynos. Instead: >>> - def_bool y if ARCH_EXYNOS >>> - depends on !ARM64 >>> + bool "Exynos multi core timer driver" if ARM >>> + depends on ARCH_EXYNOS || COMPILE_TEST >>> + default y if ARCH_EXYNOS >>> >>> This way we avoid select (which is a reverse dependency for the driver), >>> have it auto-selectable and compile tested on arm. >> >> I think you misunderstood the patch I sent. >> >> It does two things: >> >> 1. Follow the thumb of rule of the current Kconfig format >> >> - The timer driver is selected by the platform (exynos in this case) >> - User can't select the driver in the menuconfig >> - There is no dependency on the platform except for compilation test >> >> 2. Add the COMPILE_TEST >> >> - User can select the driver for compilation testing. This is for >> allyesconfig when doing compilation test coverage (exynos timer could be >> compiled on other platform). As the delay code is not portable, we have >> to restrict the compilation on the ARM platform, this is why there is >> the dependency on ARM. >> >> I am currently looking at splitting the delay code in order to prevent >> this restriction on this driver and some others drivers. > > I suspect this will come up again in the future. The problem is > really that drivers/clocksource has different rules from almost > everything else, by requiring the platform to 'select' the driver. > > The second version that Krzysztof posted is how we handle this in > other driver subsystems, and I would generally prefer it to do this > consistently for everything, but John Stultz has in the past argued > strongly for using 'select' in all clocksource drivers. The reason > is that for each platform we know in advance which driver we want, > and there is never a need for the user to have to select the right > one. Arnd, Daniel, Sure, makes sense to me, thanks for explanation. Actually this makes me thinking that drivers/soc/* should probably follow the same convention... but not all of them do that. Anyway the patch worked fine and with explanation I can only confirm: Tested-by: Krzysztof Kozlowski Reviewed-by: Krzysztof Kozlowski Best regards, Krzysztof