From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756429AbcIPHHh (ORCPT ); Fri, 16 Sep 2016 03:07:37 -0400 Received: from mailout3.w1.samsung.com ([210.118.77.13]:32900 "EHLO mailout3.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752856AbcIPHH2 (ORCPT ); Fri, 16 Sep 2016 03:07:28 -0400 X-AuditID: cbfec7f1-f79f46d0000008eb-57-57db9a2b7686 Subject: Re: [PATCH v2] leds: Introduce userspace leds driver To: David Lechner , Pavel Machek Cc: Richard Purdie , linux-kernel@vger.kernel.org, linux-leds@vger.kernel.org, Marcel Holtmann From: Jacek Anaszewski Message-id: Date: Fri, 16 Sep 2016 09:07:21 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-version: 1.0 In-reply-to: <48ba9d0b-9718-8411-3a1e-c2dd19f0adb5@lechnology.com> Content-type: text/plain; charset=windows-1252; format=flowed Content-transfer-encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFupgleLIzCtJLcpLzFFi42LZduznOV3tWbfDDT4tkbBY1CBmcXnXHDaL rW/WMVp8+/SL0eLuqaNsFrt3PWV1YPNYv3s5u8en/pOsHnvm/2D1WLH6O7vH501yAaxRXDYp qTmZZalF+nYJXBn7NlxnLWgRrOiY38TSwHiMt4uRk0NCwERi456nbBC2mMSFe+vBbCGBpYwS vWdiuhi5gOzPjBIdVw6xwDT83TuHESKxjFHi0eZ2NgjnGaPEzltfmECqhAVsJX6+/Q3WISLg KnHpynxWEJtZoJNR4uTxEhCbTcBQ4ueL10D1HBy8AnYSB6crg5gsAqoSCy/FgJiiAhESu++m ghTzCghK/Jh8D2wgp4CTxJzVD1kgBjpKPFi0E2q4vMTmNW+ZIc5cxC7x+aw6yBgJAVmJTQeg wi4SV9q/QdnCEq+Ob2GHsGUkOjsOMoE8IiEwmVHi4rGbrBDOakaJjZ2dUL9bSzT8/wW1mE9i 0rbpzBALeCU62oQgSjwkHv36AlXuKDFpA8gyUOjcYJL492Mm+wRG+VlI/pmF5IdZSH5YwMi8 ilEktbQ4Nz212EivODG3uDQvXS85P3cTIzB9nP53/OMOxvcnrA4xCnAwKvHwrph7K1yINbGs uDL3EKMEB7OSCG/btNvhQrwpiZVVqUX58UWlOanFhxilOViUxHn3LLgSLiSQnliSmp2aWpBa BJNl4uCUamB09q58GhAsya5VPO1Srtet3n9z9k9t+7g8a+/ZsiP3lbovfOb/+Mvm4qM/91a/ /rWo60z09wVfVt7YqyfUHGx1WjPgMn/Zkg19EtnzXGWP3DG/vnOGhWRp3rFYnv2abIGud75G 3w5c7uewIu5gTsG0vUu8Ty9rrvkf/OTrn6X/3noK/3C9eaB1sRJLcUaioRZzUXEiAHj0XHgb AwAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrNIsWRmVeSWpSXmKPExsVy+t/xq7r/Zt4ONzh5zNhiUYOYxeVdc9gs tr5Zx2jx7dMvRou7p46yWeze9ZTVgc1j/e7l7B6f+k+yeuyZ/4PVY8Xq7+wenzfJBbBGudlk pCampBYppOYl56dk5qXbKoWGuOlaKCnkJeam2ipF6PqGBCkplCXmlAJ5RgZowME5wD1YSd8u wS1j34brrAUtghUd85tYGhiP8XYxcnJICJhI/N07hxHCFpO4cG89WxcjF4eQwBJGiZdXJzND OM8YJTY8OgBWJSxgK/Hz7W8WEFtEwFXi0pX5rBBFN5gkzr1dxwLiMAt0Mkp0H18OVsUmYCjx 88Vrpi5GDg5eATuJg9OVQUwWAVWJhZdiQCpEBSIkbq36CDafV0BQ4sfke2CdnAJOEnNWPwSz mYH2Lni/DsqWl9i85i3zBEaBWUhaZiEpm4WkbAEj8ypGkdTS4tz03GJDveLE3OLSvHS95Pzc TYzAiNp27OfmHYyXNgYfYhTgYFTi4Q2YfStciDWxrLgy9xCjBAezkghv27Tb4UK8KYmVValF +fFFpTmpxYcYTYF+mMgsJZqcD4z2vJJ4QxNDc0tDI2MLC3MjIyVx3pIPV8KFBNITS1KzU1ML Uotg+pg4OKUaGGXnrHL0vu2/KKf0cRjTBaeH3dU9D2MuzD3e2+RrvdZkRb1B6Za8p/c7jLbM LOOJSpqu5bJLbov5IiGL6dFnZaO+TVtrc/el59WJHEf2e+95dvbXdvUPBw9OXVH6XzE15eWX /w5GOz8tcXLnn+X9Z2vuWWZbDil5wWTGC7Obwjev/sVd4h71LEyJpTgj0VCLuag4EQAFaRI1 vgIAAA== X-MTR: 20000000000000000@CPGS X-CMS-MailID: 20160916070722eucas1p13e518bf3ed2aa8e0fd5fa30178bf2157 X-Msg-Generator: CA X-Sender-IP: 182.198.249.179 X-Local-Sender: =?UTF-8?B?SmFjZWsgQW5hc3pld3NraRtTUlBPTC1TeXN0ZW0gRlcgIChN?= =?UTF-8?B?Qikb7IK87ISx7KCE7J6QG1NlbmlvciBTb2Z0d2FyZSBFbmdpbmVlcg==?= X-Global-Sender: =?UTF-8?B?SmFjZWsgQW5hc3pld3NraRtTUlBPTC1TeXN0ZW0gRlcgIChN?= =?UTF-8?B?QikbU2Ftc3VuZyBFbGVjdHJvbmljcxtTZW5pb3IgU29mdHdhcmUgRW5naW5l?= =?UTF-8?B?ZXI=?= X-Sender-Code: =?UTF-8?B?QzEwG0VIURtDMTBDRDAyQ0QwMjc1MjY=?= CMS-TYPE: 201P X-HopCount: 7 X-CMS-RootMailID: 20160915130121eucas1p2c9d50e28e391714182b63eb29709847b X-RootMTR: 20160915130121eucas1p2c9d50e28e391714182b63eb29709847b References: <1473361440-9668-1-git-send-email-david@lechnology.com> <84510542-4faa-9763-611a-be3890f3f1f7@samsung.com> <20160915130110.GI13132@amd> <69e2865f-8ba9-ea1a-594f-3de4131e3ea2@samsung.com> <48ba9d0b-9718-8411-3a1e-c2dd19f0adb5@lechnology.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi David, On 09/15/2016 05:25 PM, David Lechner wrote: > On 09/15/2016 09:54 AM, Jacek Anaszewski wrote: >> Hi Pavel, >> >> On 09/15/2016 03:01 PM, Pavel Machek wrote: >>> Hi! >>> >>>>> @@ -0,0 +1,23 @@ >>>>> +/* >>>>> + * Userspace driver support for leds subsystem >>>>> + * >>>>> + * This program is free software; you can redistribute it and/or >>>>> modify >>>>> + * it under the terms of the GNU General Public License as >>>>> published by >>>>> + * the Free Software Foundation; either version 2 of the License, or >>>>> + * (at your option) any later version. >>>>> + * >>>>> + * This program is distributed in the hope that it will be useful, >>>>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of >>>>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the >>>>> + * GNU General Public License for more details. >>>>> + */ >>>>> +#ifndef _UAPI__ULEDS_H_ >>>>> +#define _UAPI__ULEDS_H_ >>>>> + >>>>> +#define ULEDS_MAX_NAME_SIZE 80 >>>>> + >>>>> +struct uleds_user_dev { >>>>> + char name[ULEDS_MAX_NAME_SIZE]; >>>>> +}; >>> >>> We already have path component length limit somewhere, right? Just use >>> it? >>> >>> (And is struct with char array good idea at all? Perphaps it can just >>> use write() length up to something reasonable, and not bother with new >>> header file for userspace?) >> >> In fact in this case the addition of another public header can be >> avoided. >> > > The main reason I did it this way is in case someone wants to extend > this to also, for example, set the max_brightness value. If we use an > arbitrary size string, we could never add max_brightness without > breaking userspace. > > If we are sure we will never want to pass any other parameters other > than name, then we can do away with the struct. This is sound argument. Let's limit the name size to 64, as in case of name variable in led_classdev_register(). This patch could also add include directive "#include " to drivers/leds/led-class.c and replace 64 with a new LED_MAX_NAME_LEN macro defined in the uleds.h header. -- Best regards, Jacek Anaszewski