From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753894AbdFSKna (ORCPT ); Mon, 19 Jun 2017 06:43:30 -0400 Received: from mail-wm0-f67.google.com ([74.125.82.67]:35775 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753769AbdFSKn2 (ORCPT ); Mon, 19 Jun 2017 06:43:28 -0400 Date: Mon, 19 Jun 2017 12:43:25 +0200 From: Pali =?utf-8?B?Um9ow6Fy?= To: Kai-Heng Feng Cc: andy@infradead.org, mjg59@srcf.ucam.org, dvhart@infradead.org, platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] platform/x86: dell-laptop: Fix bogus keyboard backlight sysfs interface Message-ID: <20170619104325.GC32387@pali> References: <20170619102739.30449-1-kai.heng.feng@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20170619102739.30449-1-kai.heng.feng@canonical.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Monday 19 June 2017 18:27:39 Kai-Heng Feng wrote: > Dell Latitude 3160 does not have keyboard backlight, but there is a > sysfs interface for it, which does nothing at all. > > KBD_LED_ON_TOKEN is the only token can be found. Since it doesn't have > KBD_LED_OFF_TOKEN or KBD_LED_AUTO_*_TOKEN, it should be safe to assume > at least both ON and OFF token should be present to support keyboard > backlight. This is not truth. E.g. E6440 does not have ON token, but has more AUTO tokens. > Models which do not use SMBIOS token to control keyboard backlight, also > have this issue. Brightness level is 0 on these models. Verified on Dell > Inspiron 3565. > > Reports keyboard backlight is supported only when at least two modes are > present. > > Signed-off-by: Kai-Heng Feng But logic in code looks to be correct now. So fix commit message and you can add my Reviewed-by. > --- > > v3: > Change the logic, there should be at least two modes present to claim it > supports backlight. Suggested by Pali Rohár. > > v2: > The only token can be found is actually KBD_LED_ON_TOKEN, which is BIT(5), > instead of KBD_LED_OFF_TOKEN. Change commit log accordingly. > > Use token bit to make the intention more clear. > Also consider kbd_mode_levels_count and kbd_info.levels, suggested by > Pali Rohár. > > Use XOR to simplify the bitmask comparison, suggested by > Andy Shevchenko. > > drivers/platform/x86/dell-laptop.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c > index ec202094bd50..f42159fd2031 100644 > --- a/drivers/platform/x86/dell-laptop.c > +++ b/drivers/platform/x86/dell-laptop.c > @@ -1510,7 +1510,11 @@ static void kbd_init(void) > ret = kbd_init_info(); > kbd_init_tokens(); > > - if (kbd_token_bits != 0 || ret == 0) > + /* > + * Only supports keyboard backlight when it has at least two modes. > + */ > + if ((ret == 0 && (kbd_info.levels != 0 || kbd_mode_levels_count >= 2)) > + || kbd_get_valid_token_counts() >= 2) > kbd_led_present = true; > } > -- Pali Rohár pali.rohar@gmail.com