From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755905AbcKVNmE (ORCPT ); Tue, 22 Nov 2016 08:42:04 -0500 Received: from lelnx193.ext.ti.com ([198.47.27.77]:34669 "EHLO lelnx193.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754042AbcKVNlS (ORCPT ); Tue, 22 Nov 2016 08:41:18 -0500 From: Peter Ujfalusi To: , CC: , , , , Subject: [PATCH v4 0/2] backlight: pwm_bl: Fix the initial power state selection Date: Tue, 22 Nov 2016 15:41:21 +0200 Message-ID: <20161122134123.1209-1-peter.ujfalusi@ti.com> X-Mailer: git-send-email 2.11.0.rc2 MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Changes since v3: - Change 'pwm' to 'PWM' in comments and commit message - Extended the comment before we change the GPIO direction and state in case it was set as input initially. - Acked/Review-by added from Philipp and Thierry Changes since v2: - Do not change the way how the GPIO initially configured as input is handled. Configure it as output and set it's state as active. Changes since v1: - Handling of the enable GPIO is reworked: - Only change direction to output when the pin was input and in this case set the GPIO line physical low - With this change we can ensure that the enable GPIO is output so we do not need to check the direction of it later on. Cover letter: 3698d7e7d221 backlight: pwm_bl: Avoid backlight flicker when probed from DT added support for avoiding backlight flickering, which in essence was designed to not enable the baclkight when the driver loads, but let the user of the backlight to enable it later on. There are boards (like am437x-gp-evm) where we do not have valid GPIO to enable the backlight (TPS61081DRC's EN pin is connected to V3_3D) and the regulator is always on (VBAT in case of the gp-evm). In this board the logic to check the GPIO state and the regulator is failing and the backlight will be enabled as soon as the pwm_bl driver is loaded. By extending the check to look at the PWM state this issue can be avoided and the backlight will be enabled only when it's user is asking it to be enabled. Regards, Peter --- Peter Ujfalusi (2): backlight: pwm_bl: Move the checks for initial power state to a separate function backlight: pwm_bl: Check the PWM state for initial backlight power state drivers/video/backlight/pwm_bl.c | 60 +++++++++++++++++++++++++++------------- 1 file changed, 41 insertions(+), 19 deletions(-) -- 2.11.0.rc2