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 X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 74E30C0650F for ; Tue, 30 Jul 2019 16:08:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 54F7B20644 for ; Tue, 30 Jul 2019 16:08:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729306AbfG3QIm (ORCPT ); Tue, 30 Jul 2019 12:08:42 -0400 Received: from mga12.intel.com ([192.55.52.136]:35661 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727698AbfG3QIl (ORCPT ); Tue, 30 Jul 2019 12:08:41 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 30 Jul 2019 09:08:40 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,327,1559545200"; d="scan'208";a="323249179" Received: from smile.fi.intel.com (HELO smile) ([10.237.68.145]) by orsmga004.jf.intel.com with ESMTP; 30 Jul 2019 09:08:38 -0700 Received: from andy by smile with local (Exim 4.92) (envelope-from ) id 1hsUg1-0005Nn-AA; Tue, 30 Jul 2019 19:08:37 +0300 Date: Tue, 30 Jul 2019 19:08:37 +0300 From: Andy Shevchenko To: Hans de Goede Cc: Thierry Reding , linux-pwm@vger.kernel.org, linux-acpi@vger.kernel.org, youling257@gmail.com, Nikolaus Voss Subject: Re: [PATCH 5.3 regression fix] pwm: Fallback to the static lookup-list when acpi_pwm_get fails Message-ID: <20190730160837.GU23480@smile.fi.intel.com> References: <20190730154848.5164-1-hdegoede@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190730154848.5164-1-hdegoede@redhat.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Tue, Jul 30, 2019 at 05:48:48PM +0200, Hans de Goede wrote: > Commit 4a6ef8e37c4d ("pwm: Add support referencing PWMs from ACPI") > made pwm_get unconditionally return the acpi_pwm_get return value if > the device passed to pwm_get has an ACPI fwnode. > > But even if the passed in device has an ACPI fwnode, it does not > necessarily have the necessary ACPI package defining its pwm bindings, > especially since the binding / API of this ACPI package has only been > introduced very recently. > > Up until now X86/ACPI devices which use a separate pwm controller for > controlling their LCD screen's backlight brightness have been relying > on the static lookup-list to get their pwm. > > pwm_get unconditionally returning the acpi_pwm_get return value breaks > this, breaking backlight control on these devices. > > This commit fixes this by making pwm_get fall back to the static > lookup-list if acpi_pwm_get returns -ENOENT. > Reviewed-by: Andy Shevchenko Perhaps, we may switch to swnode API instead of lookup tables in the future? > BugLink: https://bugs.freedesktop.org/show_bug.cgi?id=96571 > Reported-by: youling257@gmail.com > Fixes: 4a6ef8e37c4d ("pwm: Add support referencing PWMs from ACPI") > Cc: Nikolaus Voss > Signed-off-by: Hans de Goede > --- > drivers/pwm/core.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c > index c3ab07ab31a9..8edfac17364e 100644 > --- a/drivers/pwm/core.c > +++ b/drivers/pwm/core.c > @@ -882,8 +882,11 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id) > return of_pwm_get(dev, dev->of_node, con_id); > > /* then lookup via ACPI */ > - if (dev && is_acpi_node(dev->fwnode)) > - return acpi_pwm_get(dev->fwnode); > + if (dev && is_acpi_node(dev->fwnode)) { > + pwm = acpi_pwm_get(dev->fwnode); > + if (!IS_ERR(pwm) || PTR_ERR(pwm) != -ENOENT) > + return pwm; > + } > > /* > * We look up the provider in the static table typically provided by > -- > 2.21.0 > -- With Best Regards, Andy Shevchenko