From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751753AbeCNKwf (ORCPT ); Wed, 14 Mar 2018 06:52:35 -0400 Received: from mail-wm0-f67.google.com ([74.125.82.67]:53845 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751344AbeCNKwe (ORCPT ); Wed, 14 Mar 2018 06:52:34 -0400 X-Google-Smtp-Source: AG47ELttUH5nhfWBuUBSHC3uqIZtpq7jf+pZi8zD/qr3S7xzuUYF9YOzhin6b7LHykEmBv46aZ/06w== Date: Wed, 14 Mar 2018 11:52:30 +0100 From: Thierry Reding To: Arnd Bergmann Cc: David Airlie , Philippe CORNU , Linus Walleij , dri-devel , Linux Kernel Mailing List Subject: Re: [PATCH] drm/panel: rm68200: add backlight dependency Message-ID: <20180314105230.GA8564@ulmo> References: <20180313210015.3344380-1-arnd@arndb.de> <20180313230155.GC23414@mithrandir> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="ZGiS0Q5IWpPtfppv" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --ZGiS0Q5IWpPtfppv Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Mar 14, 2018 at 09:49:54AM +0100, Arnd Bergmann wrote: > On Wed, Mar 14, 2018 at 12:01 AM, Thierry Reding > wrote: > > On Tue, Mar 13, 2018 at 09:59:54PM +0100, Arnd Bergmann wrote: > >> Like many other panel drivers, this one fails to build > >> when backlight support is disabled: > >> > >> drivers/gpu/drm/panel/panel-raydium-rm68200.o: In function `rm68200_pr= obe': > >> panel-raydium-rm68200.c:(.text+0x14a): undefined reference to `devm_of= _find_backlight' > >> > >> This adds the appropriate dependency. > >> > >> Fixes: 2b7ed18bed1a ("drm/panel: Add support for Raydium RM68200 panel= driver") > >> Signed-off-by: Arnd Bergmann > >> --- > >> drivers/gpu/drm/panel/Kconfig | 1 + > >> 1 file changed, 1 insertion(+) > > > > This shouldn't be necessary. include/linux/backlight.h defines a stub if > > the backlight class is not enabled. > > > > What tree are you seeing this on? >=20 > This is on linux-next. >=20 > It must be with BACKLIGHT_CLASS_DEVICE=3Dm and > DRM_PANEL_RAYDIUM_RM68200=3Dy, meaning that it should > be sufficient to do >=20 > depends on BACKLIGHT_CLASS_DEVICE || BACKLIGHT_CLASS_DEVICE=3Dn >=20 > to force DRM_PANEL_RAYDIUM_RM68200 to be a loadable module > whenever BACKLIGHT_CLASS_DEVICE=3Dm. For the patch, I looked at > what the other drivers in the same directory do and followed their > example. >=20 > I see three options here: >=20 > 1. update my patch changelog with the explanation I wrote here but leave = it > untouched > 2. use the more elaborate dependency (after testing) but not change the > others > 3. change all panel drivers with a backlight dependency the same way, > possibly with a helper symbol like >=20 > config BACKLIGHT_CLASS_DEVICE_OPTIONAL > tristate > default m if BACKLIGHT_CLASS_DEVICE=3Dm > default y >=20 > Arnd I went with option 1) and added some text that hopefully clarifies the issue. https://cgit.freedesktop.org/drm/drm-misc/commit/?id=3Da8efe516316472ac771= ba3f591295c7515e46172 Thierry --ZGiS0Q5IWpPtfppv Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEiOrDCAFJzPfAjcif3SOs138+s6EFAlqo/usACgkQ3SOs138+ s6FYnA//V6eEr7KbIo9gFPRDOu5Oowu2JrydOtAnOEB/GzyDiO+FEZdr387RUIny 5XUSxIZS/Jv7cN3oFtsKrbHtiKkTi6DT2UQIzSGwMt9gxZZRhni9JvFVksvO7rWW EhbrihnfFfLH0Bs/PSDV2AMwPWKC/cQilqt6AAgpCgYRVEkRyVluQoKDzMz97fXq 3GHVXQXhUDuS5ZoQkmpXnYtf80KeOe1BHcL63PcQ41YF5XQ5YJ+t2WYPQLeiKNkW uxi9Lsy0LyfI1YSUYIK79lyHBYGjEN54yj1xL7tiIV5jBsKgLCDjrBHatr7aDP7V 3rKslFSYHkG2Rrr9tyPv2RMqFAJhwxnqxezI5sOcYkvZAwTID53aV2dmpFNaTMO4 Mk/BlVq4CxIL59MArY8SbZpv0mJM5Qy2WtPN/h5DzhWM5/Im4O3KaCSRua3c58yj w5oIAuRk/qIKOPIMy6tjt+gjD2CrewGWFJy1S4bKOQY7tK+HCMoppF4ZF+ckM+9Y R0yUk4nv1V8F+TDRPZbN8Mkf4JyWb3BTmcPhWBNxrAbrVDek06rfWOCx7TRGcbH3 QP8vI2gkkBVI8Vq/V7RS7kBMpHMS5mo0vH2OBzJ4isdnfHbffHVq5jcu3/Ygw7UK Bz6Vx7YspBKuLx6ri4SGiRcP6/3l6t9f4z2iaTPCzC/pVdlvnqY= =mX/c -----END PGP SIGNATURE----- --ZGiS0Q5IWpPtfppv--