From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753751AbdFSHgk (ORCPT ); Mon, 19 Jun 2017 03:36:40 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:38854 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752531AbdFSHgi (ORCPT ); Mon, 19 Jun 2017 03:36:38 -0400 From: Kai-Heng Feng To: pali.rohar@gmail.com Cc: andy@infradead.org, mjg59@srcf.ucam.org, dvhart@infradead.org, platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org, Kai-Heng Feng Subject: [PATCH v2] platform/x86: dell-laptop: Fix bogus keyboard backlight sysfs interface Date: Mon, 19 Jun 2017 15:36:29 +0800 Message-Id: <20170619073629.14239-1-kai.heng.feng@canonical.com> X-Mailer: git-send-email 2.13.1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 it does not support keyboard backlight. Models which do not use SMBIOS 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 tokens other than KBD_LED_ON_TOKEN can be found, or brightness level is not 0. Signed-off-by: Kai-Heng Feng --- 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 | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c index ec202094bd50..4b21fc982cb0 100644 --- a/drivers/platform/x86/dell-laptop.c +++ b/drivers/platform/x86/dell-laptop.c @@ -1148,6 +1148,15 @@ static const int kbd_tokens[] = { KBD_LED_ON_TOKEN, }; +enum kbd_led_token_bit { + KBD_LED_TOKEN_BIT_OFF = 0, + KBD_LED_TOKEN_BIT_AUTO_25, + KBD_LED_TOKEN_BIT_AUTO_50, + KBD_LED_TOKEN_BIT_AUTO_75, + KBD_LED_TOKEN_BIT_AUTO_100, + KBD_LED_TOKEN_BIT_ON, +}; + static u16 kbd_token_bits; static struct kbd_info kbd_info; @@ -1510,7 +1519,12 @@ static void kbd_init(void) ret = kbd_init_info(); kbd_init_tokens(); - if (kbd_token_bits != 0 || ret == 0) + /* + * If brightness level is 0, or KBD_LED_ON_TOKEN is the only token, + * consider there is no keyboard backlight. + */ + if ((ret == 0 && (kbd_info.levels || kbd_mode_levels_count)) || + kbd_token_bits ^ BIT(KBD_LED_TOKEN_BIT_ON)) kbd_led_present = true; } -- 2.13.1