From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5DA57ECE561 for ; Mon, 24 Sep 2018 13:59:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 130C92098A for ; Mon, 24 Sep 2018 13:59:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 130C92098A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=st.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730926AbeIXUCI (ORCPT ); Mon, 24 Sep 2018 16:02:08 -0400 Received: from mx07-00178001.pphosted.com ([62.209.51.94]:15102 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728809AbeIXUCI (ORCPT ); Mon, 24 Sep 2018 16:02:08 -0400 Received: from pps.filterd (m0046668.ppops.net [127.0.0.1]) by mx07-.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id w8ODrpGt025143; Mon, 24 Sep 2018 15:59:06 +0200 Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-00178001.pphosted.com with ESMTP id 2mnb6x3jgd-1 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT); Mon, 24 Sep 2018 15:59:06 +0200 Received: from zeta.dmz-eu.st.com (zeta.dmz-eu.st.com [164.129.230.9]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 575FD46; Mon, 24 Sep 2018 13:59:05 +0000 (GMT) Received: from Webmail-eu.st.com (sfhdag5node3.st.com [10.75.127.15]) by zeta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 2C362A57D; Mon, 24 Sep 2018 13:59:05 +0000 (GMT) Received: from [10.48.0.167] (10.75.127.45) by SFHDAG5NODE3.st.com (10.75.127.15) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Mon, 24 Sep 2018 15:59:04 +0200 Subject: Re: [RESEND PATCH] Revert "pwm: Set class for exported channels in sysfs" To: Thierry Reding CC: , , , , , , , , , References: <1537538567-5377-1-git-send-email-fabrice.gasnier@st.com> <20180924115301.GV21032@ulmo> From: Fabrice Gasnier Message-ID: Date: Mon, 24 Sep 2018 15:59:03 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180924115301.GV21032@ulmo> Content-Type: text/plain; charset="windows-1252" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.75.127.45] X-ClientProxiedBy: SFHDAG7NODE3.st.com (10.75.127.21) To SFHDAG5NODE3.st.com (10.75.127.15) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-09-24_08:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/24/2018 01:53 PM, Thierry Reding wrote: > On Fri, Sep 21, 2018 at 04:02:47PM +0200, Fabrice Gasnier wrote: >> This reverts commit 7e5d1fd75c3dde9fc10c4472b9368089d1b81d00 as it causes >> regression with multiple pwm chip. It creates a new entry in >> '/sys/class/pwm' every time a 'pwmX' is exported with 'echo X > export': >> - 1st time export will create an entry in /sys/class/pwm/pwmX >> - when another export happens on another pwmchip, it can't be created >> (e.g. -EEXIST) >> >> This also changes existing ABI (Documentation/ABI/testing/sysfs-class-pwm): >> - pmwX should be there: /sys/class/pwm/pwmchipN/pwmX >> >> Example on stm32 (stm32429i-eval) platform: >> $ ls /sys/class/pwm >> pwmchip0 pwmchip4 >> >> $ cd /sys/class/pwm/pwmchip0/ >> $ echo 0 > export >> $ ls /sys/class/pwm >> pwm0 pwmchip0 pwmchip4 >> >> $ cd /sys/class/pwm/pwmchip4/ >> $ echo 0 > export >> sysfs: cannot create duplicate filename '/class/pwm/pwm0' >> ...Exception stack follows... >> >> Signed-off-by: Fabrice Gasnier >> --- >> drivers/pwm/sysfs.c | 1 - >> 1 file changed, 1 deletion(-) > > Can we come up with an alternative that allows us to have both? We want > uevent and proper sysfs creation, or is that not possible? Hi Thierry, all, With current approach: - "export->child.class = parent->class" - ABI (e.g. "pwm%d") device name isn't unique with multiple pwm chip. I think this is not possible. Trying to think of an alternative... I just did a quick test, by changing device name, to take pwmchip into account: + export->child.class = parent->class; export->child.release = pwm_export_release; export->child.parent = parent; export->child.devt = MKDEV(0, 0); export->child.groups = pwm_groups; - dev_set_name(&export->child, "pwm%u", pwm->hwpwm); + dev_set_name(&export->child, "pwmchip%d-pwm%u", chip->base, pwm->hwpwm); But this also impacts existing ABI :-( Would you have suggestions to send an uevent, without modifying ABI ? Please advise, Best regards, Fabrice > > Thierry >