Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964951AbdDSUUi (ORCPT ); Wed, 19 Apr 2017 16:20:38 -0400 Received: from galahad.ideasonboard.com ([185.26.127.97]:39792 "EHLO galahad.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936908AbdDSUUf (ORCPT ); Wed, 19 Apr 2017 16:20:35 -0400 From: Laurent Pinchart To: Arnd Bergmann Cc: Tomi Valkeinen , David Airlie , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] drm/omap: displays: panel-dpi: add backlight dependency Date: Wed, 19 Apr 2017 23:21:35 +0300 Message-ID: <2979804.i6EKSW6ohY@avalon> User-Agent: KMail/4.14.10 (Linux/4.9.16-gentoo; KDE/4.14.29; x86_64; ; ) In-Reply-To: <20170419175939.189098-1-arnd@arndb.de> References: <20170419175939.189098-1-arnd@arndb.de> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2593 Lines: 75 Hi Arnd, Thank you for the patch. On Wednesday 19 Apr 2017 19:59:17 Arnd Bergmann wrote: > The panel driver gained support for backlight but fails to link now > when that is disabled: > > drivers/gpu/drm/omapdrm/displays/panel-dpi.o: In function > `panel_dpi_probe_of': panel-dpi.c:(.text.panel_dpi_probe_of+0xe8): > undefined reference to `of_find_backlight_by_node' > > This adds a dependency like we have for the other panel drivers. I believe the dependency should be made optional. DPI panels that don't need backlight control should be supported by a kernel that has backlight support compiled out. How about something like >From 07a98ab23b2080c79abbf8b5e7479123c50e6be7 Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Wed, 19 Apr 2017 23:13:43 +0300 Subject: [PATCH] backlight: Define API stub when backlight support is disabled The of_find_backlight_by_node() function has a stubbed when CONFIG_OF is disabled, but drivers that use backlights optionally will still fail to link if backlight support is disabled. Fix it by defining the stub when CONFIG_BACKLIGHT_CLASS_DEVICE is disabled. Signed-off-by: Laurent Pinchart --- include/linux/backlight.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/backlight.h b/include/linux/backlight.h index 5f2fd61ef4fb..fae0b189f7b4 100644 --- a/include/linux/backlight.h +++ b/include/linux/backlight.h @@ -162,7 +162,7 @@ struct generic_bl_info { void (*kick_battery)(void); }; -#ifdef CONFIG_OF +#if IS_ENABLED(CONFIG_OF) && IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE) struct backlight_device *of_find_backlight_by_node(struct device_node *node); #else static inline struct backlight_device * We might need to create stubs for backlight_force_update() and backlight_device_set_brightness() too. > Fixes: 39135a305a0f ("drm/omap: displays: panel-dpi: Support for handling > backlight devices") > Signed-off-by: Arnd Bergmann > --- > drivers/gpu/drm/omapdrm/displays/Kconfig | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/gpu/drm/omapdrm/displays/Kconfig > b/drivers/gpu/drm/omapdrm/displays/Kconfig index c226da145fb3..a349cb61961e > 100644 > --- a/drivers/gpu/drm/omapdrm/displays/Kconfig > +++ b/drivers/gpu/drm/omapdrm/displays/Kconfig > @@ -35,6 +35,7 @@ config DRM_OMAP_CONNECTOR_ANALOG_TV > > config DRM_OMAP_PANEL_DPI > tristate "Generic DPI panel" > + depends on BACKLIGHT_CLASS_DEVICE > help > Driver for generic DPI panels. -- Regards, Laurent Pinchart