From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 359A4EE49A8 for ; Mon, 21 Aug 2023 07:13:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233600AbjHUHNg (ORCPT ); Mon, 21 Aug 2023 03:13:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58408 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233594AbjHUHNf (ORCPT ); Mon, 21 Aug 2023 03:13:35 -0400 Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.31]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 06B4CB1 for ; Mon, 21 Aug 2023 00:13:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1692602011; x=1724138011; h=from:to:cc:subject:in-reply-to:references:date: message-id:mime-version; bh=av4oCu9sjI/1tXAcnOs+Fnjxj3bZRnRW6Vu6VY0dHhA=; b=Xv98Ole8Ak09pG71wF9lFpPnOduy90+01jkUlaTc08wz9sWoSxQr+ODY 6tmTJoMhUCq6O5vmvFsG3glr/51KRFUPUNwdqiPtHdOYh/qVLU/0EbHpc pxhxfK1fmdVVsxuOisUTjG/icdynPug57ZHbODnauJNN/ltRZrFJKSJbN IUOD1SESzSXkrNPnvurtaQHamH/lD+NdcAH+sRuxgFfu4XWaHQP5UaAJz MFDkP6PA6sgOdZZLtJ3SUqWjUrNd1e1J7eLXEKhoGfe39htWQ1TAzevG2 iKg00HWvR7xHq0n50nIP3LFi30BEIdWqBDHvbpnpMbm/BMvOsasn381k4 w==; X-IronPort-AV: E=McAfee;i="6600,9927,10808"; a="437437554" X-IronPort-AV: E=Sophos;i="6.01,189,1684825200"; d="scan'208";a="437437554" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Aug 2023 00:13:20 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10808"; a="738801231" X-IronPort-AV: E=Sophos;i="6.01,189,1684825200"; d="scan'208";a="738801231" Received: from hpabst-mobl.ger.corp.intel.com (HELO localhost) ([10.252.54.190]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Aug 2023 00:13:17 -0700 From: Jani Nikula To: ZNdOoHvIg7HXh7Gg@fedora, Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , David Airlie , Daniel Vetter , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Cc: stone.xulei@xfusion.com Subject: Re: [Intel-gfx] [PATCH v3] drm/i915: Fix Kconfig error for CONFIG_DRM_I915 In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: Date: Mon, 21 Aug 2023 10:13:15 +0300 Message-ID: <87wmxo7tro.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 20 Aug 2023, Wang Jinchao wrote: > When CONFIG_DRM_I915 is set to 'y' and CONFIG_BACKLIGHT_CLASS_DEVICE > is set to 'm', we encountered an ld.lld error during the build process: > > ld.lld: error: undefined symbol: backlight_device_get_by_name > >>> referenced by intel_backlight.c:955 > >>> vmlinux.o:(intel_backlight_device_register) > > ld.lld: error: undefined symbol: backlight_device_register > >>> referenced by intel_backlight.c:971 > >>> vmlinux.o:(intel_backlight_device_register) > > ld.lld: error: undefined symbol: backlight_device_unregister > >>> referenced by intel_backlight.c:999 > >>> vmlinux.o:(intel_backlight_device_unregister) > > This issue occurred because intel_backlight_device_register and > intel_backlight_device_unregister were enclosed within > \#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE) and #endif directives. > However, according to Kconfig, CONFIG_DRM_I915 will select > BACKLIGHT_CLASS_DEVICE only if ACPI is enabled. > This led to an error when ACPI is not enabled. > Change IS_ENABLED to IS_REACHABLE and use IS_REACHABLE to encompass > the implementation of intel_connector_register() to solve this issue. I told you in [1] what the real fix is. The IS_REACHABLE() solution has been suggested a number of times, but I think it's creating an unexpected and silent failure configuration. I think IS_REACHABLE() is the wrong thing to do in most cases. BR, Jani. [1] https://lore.kernel.org/r/87o7jaythm.fsf@intel.com > > Signed-off-by: Wang Jinchao > --- > drivers/gpu/drm/i915/display/intel_backlight.c | 2 +- > drivers/gpu/drm/i915/display/intel_backlight.h | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_backlight.c b/drivers/gpu/drm/i915/display/intel_backlight.c > index 2e8f17c04522..d812cdc74a84 100644 > --- a/drivers/gpu/drm/i915/display/intel_backlight.c > +++ b/drivers/gpu/drm/i915/display/intel_backlight.c > @@ -795,7 +795,7 @@ void intel_backlight_enable(const struct intel_crtc_state *crtc_state, > mutex_unlock(&i915->display.backlight.lock); > } > > -#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE) > +#if IS_REACHABLE(CONFIG_BACKLIGHT_CLASS_DEVICE) > static u32 intel_panel_get_backlight(struct intel_connector *connector) > { > struct drm_i915_private *i915 = to_i915(connector->base.dev); > diff --git a/drivers/gpu/drm/i915/display/intel_backlight.h b/drivers/gpu/drm/i915/display/intel_backlight.h > index 339643f63897..207fe1c613d8 100644 > --- a/drivers/gpu/drm/i915/display/intel_backlight.h > +++ b/drivers/gpu/drm/i915/display/intel_backlight.h > @@ -36,7 +36,7 @@ u32 intel_backlight_invert_pwm_level(struct intel_connector *connector, u32 leve > u32 intel_backlight_level_to_pwm(struct intel_connector *connector, u32 level); > u32 intel_backlight_level_from_pwm(struct intel_connector *connector, u32 val); > > -#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE) > +#if IS_REACHABLE(CONFIG_BACKLIGHT_CLASS_DEVICE) > int intel_backlight_device_register(struct intel_connector *connector); > void intel_backlight_device_unregister(struct intel_connector *connector); > #else /* CONFIG_BACKLIGHT_CLASS_DEVICE */ -- Jani Nikula, Intel Open Source Graphics Center