From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754566Ab3KLASL (ORCPT ); Mon, 11 Nov 2013 19:18:11 -0500 Received: from mailout3.samsung.com ([203.254.224.33]:8892 "EHLO mailout3.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752434Ab3KLASG (ORCPT ); Mon, 11 Nov 2013 19:18:06 -0500 X-AuditID: cbfee691-b7f866d000001b8c-7b-528173bd6801 From: Jingoo Han To: "'Kyungmin Park'" , "'Henrique de Moraes Holschuh'" Cc: linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, kay@vrfy.org, "'Richard Purdie'" , "'Jingoo Han'" , ibm-acpi-devel@lists.sourceforge.net, platform-driver-x86@vger.kernel.org References: <20131111235700.GA29987@july> In-reply-to: <20131111235700.GA29987@july> Subject: Re: [PATCH] video: backlight: Remove backlight sysfs uevent Date: Tue, 12 Nov 2013 09:18:04 +0900 Message-id: <002901cedf3c$a7e77a00$f7b66e00$%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: Ac7fOavfpiiNdH9mR/ymw66mQWj6SwAAgyKQ Content-language: ko X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrEIsWRmVeSWpSXmKPExsVy+t8zY929xY1BBotXsFvMPmxjMefZWkaL ywsvsVrcWvWc3eLW5VUsFif6PrBaXN41h81i9Z4XzBa7dz1ldeD0+H2A0WPzCi2P3Qs+M3ns mf+D1aNvyypGj8+b5Dw+rvcMYI/isklJzcksSy3St0vgyvj/bhJrwR/hilWzbrA1MHYLdDFy ckgImEis2LeBGcIWk7hwbz1bFyMXh5DAMkaJD3+vs8EU/Z7xkxEiMZ1R4uvDh1DOL0aJQ4dX sINUsQmoSXz5chjMFhFIlFh5bgUTiM0s8IRRYttkdRBbSEBTYs6JLrB1nAJaEjNWPAOrERZw kZiz8S5YL4uAqsTz1+/B4rwCthLrfy1nh7AFJX5MvscCMVNLYv3O41Dz5SU2r3kLNJMD6FJ1 iUd/dSFOMJJoWbgGqlxEYt+Ld2A3Swg0cki03zjFDLFLQOLb5EMsEL2yEpsOQENCUuLgihss ExglZiHZPAvJ5llINs9CsmIBI8sqRtHUguSC4qT0IlO94sTc4tK8dL3k/NxNjJD4nriD8f4B 60OMyUDrJzJLiSbnA9NDXkm8obGZkYWpiamxkbmlGWnCSuK86Y+SgoQE0hNLUrNTUwtSi+KL SnNSiw8xMnFwSjUwMnAZlSf2b2ZueCnQ+PvPmus3TX//eRe+2IFHttw416gz4myIZ84d3wez dDtY1SKlYj+rPax4WuNo8mPvx2l8B/WaLL5KrGq7o3mbfTaH1xOWDT7r128OX7yE9XjCuWO9 Ou/uP960w12Be+FyM48bhnu8tjWU/pd7ZnetRv//7evzFxz83ercp8RSnJFoqMVcVJwIACDH SlkFAwAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrPKsWRmVeSWpSXmKPExsVy+t9jQd29xY1BBieuM1nMPmxjMefZWkaL ywsvsVrcWvWc3eLW5VUsFif6PrBaXN41h81i9Z4XzBa7dz1ldeD0+H2A0WPzCi2P3Qs+M3ns mf+D1aNvyypGj8+b5Dw+rvcMYI9qYLTJSE1MSS1SSM1Lzk/JzEu3VfIOjneONzUzMNQ1tLQw V1LIS8xNtVVy8QnQdcvMAbpLSaEsMacUKBSQWFyspG+HaUJoiJuuBUxjhK5vSBBcj5EBGkhY x5jx/90k1oI/whWrZt1ga2DsFuhi5OSQEDCR+D3jJyOELSZx4d56ti5GLg4hgemMEl8fPmSE cH4xShw6vIIdpIpNQE3iy5fDYLaIQKLEynMrmEBsZoEnjBLbJquD2EICmhJzTnQxg9icAloS M1Y8A6sRFnCRmLPxLlgvi4CqxPPX78HivAK2Eut/LWeHsAUlfky+xwIxU0ti/c7jUPPlJTav eQs0kwPoUnWJR391IU4wkmhZuAaqXERi34t3jBMYhWYhmTQLyaRZSCbNQtKygJFlFaNoakFy QXFSeq6RXnFibnFpXrpecn7uJkZw8ngmvYNxVYPFIUYBDkYlHt4dXI1BQqyJZcWVuYcYJTiY lUR4zXOBQrwpiZVVqUX58UWlOanFhxiTgR6dyCwlmpwPTGx5JfGGxiZmRpZGZhZGJubmpAkr ifMebLUOFBJITyxJzU5NLUgtgtnCxMEp1cAoW6Ypapq6Y//jPc09DrvvNjUntV82nPw69Pn5 FXM2SF/0C9Zi9e9YuMB2+mXxHTvPPG5mN3A721duNNO1derEGXyuu8+/Onz1+DuNqE/rmnlP BW1++DrufIWx3KpXmQd3r+YU2PRUSytywpIX3x/HchQn2s5devKI/RRZxu2uyy1Upk/cpLi8 TomlOCPRUIu5qDgRAC7WMi9iAwAA 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 8:57 AM, 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 > --- > diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c > index 94a403a..441272d 100644 > --- a/drivers/video/backlight/backlight.c > +++ b/drivers/video/backlight/backlight.c > @@ -88,9 +88,6 @@ static void backlight_generate_event(struct backlight_device *bd, > char *envp[2]; > > switch (reason) { > - case BACKLIGHT_UPDATE_SYSFS: > - envp[0] = "SOURCE=sysfs"; > - break; > case BACKLIGHT_UPDATE_HOTKEY: > envp[0] = "SOURCE=hotkey"; > break; > @@ -172,8 +169,6 @@ 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); > diff --git a/include/linux/backlight.h b/include/linux/backlight.h > index 53b7794..d2a27dd 100644 > --- a/include/linux/backlight.h > +++ b/include/linux/backlight.h > @@ -29,7 +29,6 @@ > > enum backlight_update_reason { > BACKLIGHT_UPDATE_HOTKEY, > - BACKLIGHT_UPDATE_SYSFS, +cc Henrique de Moraes Holschuh (Maintainer of thinkpad_acpi) Hi Henrique de Moraes Holschuh, 'thinkpad_acpi.c' uses the 'BACKLIGHT_UPDATE_SYSFS'. Henrique, can we remove it? drivers/platform/x86/thinkpad_acpi.c if (!rc && ibm_backlight_device) backlight_force_update(ibm_backlight_device, BACKLIGHT_UPDATE_SYSFS); Best regards, Jingoo Han > }; > > enum backlight_type {