From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754075Ab3KZE1Q (ORCPT ); Mon, 25 Nov 2013 23:27:16 -0500 Received: from mailout4.samsung.com ([203.254.224.34]:56762 "EHLO mailout4.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751484Ab3KZE1M (ORCPT ); Mon, 25 Nov 2013 23:27:12 -0500 X-AuditID: cbfee691-b7f666d0000048b0-54-5294231fee77 From: Jingoo Han To: "'Andrew Morton'" Cc: "'Kyungmin Park'" , "'Richard Purdie'" , linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, "'Kay Sievers'" , "'Jingoo Han'" References: <20131112033906.GA30454@july> In-reply-to: <20131112033906.GA30454@july> Subject: Re: [PATCH v2] video: backlight: Remove backlight sysfs uevent Date: Tue, 26 Nov 2013 13:27:11 +0900 Message-id: <001001ceea5f$c6642e50$532c8af0$%han@samsung.com> MIME-version: 1.0 Content-type: text/plain; charset=us-ascii Content-transfer-encoding: 7bit X-Mailer: Microsoft Office Outlook 12.0 Thread-index: Ac7fWLLJJ5g8UvCZScqyHwCOo0hhJQLBrPQg Content-language: ko X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFnrEIsWRmVeSWpSXmKPExsVy+t8zA1155SlBBm0TlS3mrF/DZnF54SVW i1urnrNb3Lq8isXiRN8HVovLu+awWeze9ZTVgd1j8wotjxMzfrN47Jn/g9Wjb8sqRo/Pm+Q8 Pq73DGCL4rJJSc3JLEst0rdL4Mrof9rLVLCYt2LnQtsGxs9cXYwcHBICJhKn1gd0MXICmWIS F+6tZ+ti5OIQEljGKPHw0FUWiISJxNqWB+wQiUWMEjuvbIRyfjFKTGvZxwhSxSagJvHly2F2 kKkiAvoSbS0aIDXMApcZJXoX7WIHqRES0JRY+mg3I0gNp4CWxKTvmSBhYQF3iff3T7CC2CwC qhJLZ55gA7F5BWwl+pf9ZIewBSV+TL4HdhAzUOv6nceZIGx5ic1r3jJDPKMu8eivLkhYRMBI YvGDr6wQJSIS+168YwQ5R0LgK7vElZ0/mSF2CUh8m3yIBaJXVmLTAWaIfyUlDq64wTKBUWIW ks2zkGyehWTzLCQrFjCyrGIUTS1ILihOSi8y1StOzC0uzUvXS87P3cQIid+JOxjvH7A+xJgM tH4is5Rocj4w/vNK4g2NzYwsTE1MjY3MLc1IE1YS501/lBQkJJCeWJKanZpakFoUX1Sak1p8 iJGJg1OqgVFN8FB02b5sT+XXEwIYq6a7z1I+0GmzZe7B36lTGm9ICc26bl1kuDjiz/GEL5Xn g4KEj39deLknWd0nf2pGu+6CK70HAy7fZ50imaAxo9Lg/oVDH5J/XmBetqxfmE38suRdy8gf /TnKllbO3v6B3HqfzJTsd7xfHn9T7gvHxNt7cg/fqLCW1FRiKc5INNRiLipOBADGtF4n9QIA AA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrAKsWRmVeSWpSXmKPExsVy+t9jAV155SlBBl8eyVnMWb+GzeLywkus FrdWPWe3uHV5FYvFib4PrBaXd81hs9i96ymrA7vH5hVaHidm/Gbx2DP/B6tH35ZVjB6fN8l5 fFzvGcAW1cBok5GamJJapJCal5yfkpmXbqvkHRzvHG9qZmCoa2hpYa6kkJeYm2qr5OIToOuW mQN0ipJCWWJOKVAoILG4WEnfDtOE0BA3XQuYxghd35AguB4jAzSQsI4xo/9pL1PBYt6KnQtt Gxg/c3UxcnJICJhIrG15wA5hi0lcuLeerYuRi0NIYBGjxM4rG9khnF+MEtNa9jGCVLEJqEl8 +XIYKMHBISKgL9HWogFSwyxwmVGid9EusElCApoSSx/tZgSp4RTQkpj0PRMkLCzgLvH+/glW EJtFQFVi6cwTbCA2r4CtRP+yn+wQtqDEj8n3WEBsZqDW9TuPM0HY8hKb17xlBhkpIaAu8eiv LkhYRMBIYvGDr6wQJSIS+168Y5zAKDQLyaRZSCbNQjJpFpKWBYwsqxhFUwuSC4qT0nMN9YoT c4tL89L1kvNzNzGC08MzqR2MKxssDjEKcDAq8fBKdE4OEmJNLCuuzD3EKMHBrCTC63ofKMSb klhZlVqUH19UmpNafIgxGejRicxSosn5wNSVVxJvaGxiZmRpZGZhZGJuTpqwkjjvgVbrQCGB 9MSS1OzU1ILUIpgtTBycUg2MOSJ8/Hs2/j17O+D/gWPzhdd2/fj+SDNDne/VTtag0oqyrPVH q/STZk85K1KT+i6qxP/LUin30M8vU6udjDnKF33Rnbpy0yW9mv3sB0W+hmTVRu0RLF5bob7n NMePwsUz1Ffsqf5sOsecTa0tVPbPEYlJzIqblM/4ZeZFbNq6RN/4k/r8p5tnKbEUZyQaajEX FScCANj6j55TAwAA DLP-Filter: Pass X-MTR: 20000000000000000@CPGS X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday, November 12, 2013 12:39 PM, Kyungmin Park wrote: > > From: Kyungmin Park > > The most mobile phones have Ambient Light Sensors and it changes brightness according lux. > It means it changes backlight brightness frequently by just writing sysfs node, so it generates uevent. > > Usually there's no user to use this backlight changes. But it forks udev worker threads and it takes > about 5ms. The main problem is that it hurts other process activities. so remove it. > > Kay said > "Uevents are for the major, low-frequent, global device state-changes, > not for carrying-out any sort of measurement data. Subsystems which > need that should use other facilities like poll()-able sysfs file or > any other subscription-based, client-tracking interface which does not > cause overhead if it isn't used. Uevents are not the right thing to > use here, and upstream udev should not paper-over broken kernel > subsystems." > > Signed-off-by: Kyungmin Park Acked-by: Jingoo Han Best regards, Jingoo Han > --- > v1: there's still user to use BACKLIGHT_UPDATE_SYSFS. so just remove store sysfs node uevent > > --- > diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c > index 94a403a..292cf99 100644 > --- a/drivers/video/backlight/backlight.c > +++ b/drivers/video/backlight/backlight.c > @@ -172,8 +172,6 @@ static ssize_t brightness_store(struct device *dev, > } > mutex_unlock(&bd->ops_lock); > > - backlight_generate_event(bd, BACKLIGHT_UPDATE_SYSFS); > - > return rc; > } > static DEVICE_ATTR_RW(brightness);