From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2001:1868:205::9]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 6563C1A0054 for ; Wed, 22 Oct 2014 07:49:57 +1100 (AEDT) Date: Tue, 21 Oct 2014 13:50:07 -0700 From: Darren Hart To: Jani Nikula Subject: Re: [PATCH] drivers: depend on instead of select BACKLIGHT_CLASS_DEVICE and ACPI_VIDEO Message-ID: <20141021205006.GC20951@vmdeb7> References: <1413580403-16225-1-git-send-email-jani.nikula@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1413580403-16225-1-git-send-email-jani.nikula@intel.com> Cc: Jean-Christophe Plagniol-Villard , linux-fbdev@vger.kernel.org, Randy Dunlap , Daniel Drake , Jens Frederich , David Airlie , Greg Kroah-Hartman , Jon Nettleton , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, platform-driver-x86@vger.kernel.org, Tomi Valkeinen , Laurent Pinchart , Daniel Vetter , linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Sat, Oct 18, 2014 at 12:13:23AM +0300, Jani Nikula wrote: > Documentation/kbuild/kconfig-language.txt warns to use select with care, > and in general use select only for non-visible symbols and for symbols > with no dependencies, because select will force a symbol to a value > without visiting the dependencies. > > Select has become particularly problematic, interdependently, with the > BACKLIGHT_CLASS_DEVICE and ACPI_VIDEO configs. For example: > > scripts/kconfig/conf --randconfig Kconfig > KCONFIG_SEED=0x48312B00 > warning: (DRM_RADEON && DRM_NOUVEAU && DRM_I915 && DRM_GMA500 && > DRM_SHMOBILE && DRM_TILCDC && FB_BACKLIGHT && FB_MX3 && USB_APPLEDISPLAY > && FB_OLPC_DCON && ASUS_LAPTOP && SONY_LAPTOP && THINKPAD_ACPI && > EEEPC_LAPTOP && ACPI_CMPC && SAMSUNG_Q10) selects BACKLIGHT_CLASS_DEVICE > which has unmet direct dependencies (HAS_IOMEM && BACKLIGHT_LCD_SUPPORT) > warning: (DRM_RADEON && DRM_NOUVEAU && DRM_I915 && DRM_GMA500 && > DRM_SHMOBILE && DRM_TILCDC && FB_BACKLIGHT && FB_MX3 && USB_APPLEDISPLAY > && FB_OLPC_DCON && ASUS_LAPTOP && SONY_LAPTOP && THINKPAD_ACPI && > EEEPC_LAPTOP && ACPI_CMPC && SAMSUNG_Q10) selects BACKLIGHT_CLASS_DEVICE > which has unmet direct dependencies (HAS_IOMEM && BACKLIGHT_LCD_SUPPORT) > > With tristates it's possible to end up selecting FOO=y depending on > BAR=m in the config, which gets discovered at build time, not config > time, like reported in the thread referenced below. > > Do the following to fix the dependencies: > > * Depend on instead of select BACKLIGHT_CLASS_DEVICE everywhere. Drop > select BACKLIGHT_LCD_SUPPORT in such cases, as it's a dependency of > BACKLIGHT_CLASS_DEVICE. > > * Remove config FB_BACKLIGHT altogether, and replace it with a > dependency on BACKLIGHT_CLASS_DEVICE. All configs selecting > FB_BACKLIGHT select or depend on FB anyway, so we can simplify. > > * Depend on (ACPI && ACPI_VIDEO) || ACPI=n in several places instead of > selecting ACPI_VIDEO and a number of its dependencies if ACPI is > enabled. This is tied to backlight, as ACPI_VIDEO depends on > BACKLIGHT_CLASS_DEVICE. > > * Replace a couple of select INPUT/VT with depends as it seemed to be > necessary. > > Reference: http://lkml.kernel.org/r/CA+r1ZhhmT4DrWtf6MbRQo5EqXwx+LxCqh15Vsu_d9WpftLhnxw@mail.gmail.com > Reported-by: Jim Davis > Cc: Randy Dunlap > Cc: David Airlie > Cc: Daniel Vetter > Cc: Greg Kroah-Hartman > Cc: Darren Hart > Cc: Laurent Pinchart > Cc: Benjamin Herrenschmidt > Cc: Jens Frederich > Cc: Daniel Drake > Cc: Jon Nettleton > Cc: Jean-Christophe Plagniol-Villard > Cc: Tomi Valkeinen > Signed-off-by: Jani Nikula As for the drivers/platform/x86/Kconfig: Acked-by: Darren Hart Thanks, -- Darren Hart Intel Open Source Technology Center