From mboxrd@z Thu Jan 1 00:00:00 1970 From: Krzysztof Kozlowski Subject: Re: [PATCH] PM / Domains: Restrict "samsung,power-domain" checks to ARCH_EXYNOS Date: Fri, 21 Oct 2016 17:06:57 +0300 Message-ID: <20161021140657.GC3289@kozik-lap> References: <1477049656-27535-1-git-send-email-geert+renesas@glider.be> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Return-path: Received: from mail-lf0-f67.google.com ([209.85.215.67]:32798 "EHLO mail-lf0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755525AbcJUOHE (ORCPT ); Fri, 21 Oct 2016 10:07:04 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: "Rafael J. Wysocki" Cc: Geert Uytterhoeven , "Rafael J. Wysocki" , Kevin Hilman , Ulf Hansson , Kukjin Kim , Krzysztof Kozlowski , Javier Martinez Canillas , Greg Kroah-Hartman , Linux PM , "linux-arm-kernel@lists.infradead.org" , Linux Samsung SoC On Fri, Oct 21, 2016 at 02:29:05PM +0200, Rafael J. Wysocki wrote: > On Fri, Oct 21, 2016 at 1:34 PM, Geert Uytterhoeven > wrote: > > Currently the generic PM Domain code code checks for the presence of > > both (generic) "power-domains" and (Samsung Exynos legacy) > > "samsung,power-domain" properties in all device tree nodes representing > > devices. > > > > There are two issues with this: > > 1. This imposes a small boot-time penalty on all platforms using DT, > > 2. Platform-specific checks do not really belong in core framework > > code. > > > > While moving the check from platform-agnostic code to Samsung-specific > > code is non-trivial, the runtime overhead can be restricted to kernels > > including support for 32-bit Samsung Exynos platforms. > > > > Signed-off-by: Geert Uytterhoeven > > --- > > "samsung,power-domain" was only ever used in: > > - arch/arm/boot/dts/exynos4415.dtsi: Unused? > > - arch/arm/boot/dts/exynos3250.dtsi: CONFIG_ARCH_EXYNOS3 > > - arch/arm/boot/dts/exynos4.dtsi: CONFIG_ARCH_EXYNOS4 > > - arch/arm/boot/dts/exynos4x12.dtsi: CONFIG_ARCH_EXYNOS4 > > exynos4212.dtsi is unused? > > - arch/arm/boot/dts/exynos5250.dtsi: CONFIG_ARCH_EXYNOS5 > > - arch/arm/boot/dts/exynos5420.dtsi: CONFIG_ARCH_EXYNOS5 > > --- > > drivers/base/power/domain.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c > > index e023066e421547c5..d94d6a4b9b527108 100644 > > --- a/drivers/base/power/domain.c > > +++ b/drivers/base/power/domain.c > > @@ -1853,7 +1853,8 @@ int genpd_dev_pm_attach(struct device *dev) > > ret = of_parse_phandle_with_args(dev->of_node, "power-domains", > > "#power-domain-cells", 0, &pd_args); > > if (ret < 0) { > > - if (ret != -ENOENT) > > + if (ret != -ENOENT || !IS_ENABLED(CONFIG_ARCH_EXYNOS) || > > Please don't check things like CONFIG_ARCH_EXYNOS in the core. > > If you need to put checks like that here, there is a design problem somewhere. > > And imagine someone 5 years ahead from now looking at this code and > wondering why on Earth the check is here. Sorry for the noise, sending once again without bogus recipient added by mistake: I don't find the argument of performance penalty such important but for the sake of design, the samsung-specific code could be moved to drivers/soc/samsung/pm_domains.c, called "legacy_pm_parse" and exported through a header. Thus with !ARCH_EXYNOS that would be 'static inline {}'. However that is not a nice solution - there will be still direct call to platform-specific code in the core. I am not sure if it is worth the effort. The samsung,power-domain was made deprecated (although not explicitly) in January 2015 (0da658704136 ("ARM: dts: convert to generic power domain bindings for exynos DT")) so how about: 1. Printing a dev_warn() about usage of deprecated bindings. 2. Complete removal in January 2017? Best regards, Krzysztof