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smtp.mailfrom=Michal.Vokac@ysoft.com; Received: from [10.1.8.111] (89.24.100.190) by AM0PR04MB4658.eurprd04.prod.outlook.com (2603:10a6:208:75::12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.1185.24; Mon, 1 Oct 2018 16:27:19 +0000 Subject: Re: [PATCH v2 1/2] Revert "pwm: Set class for exported channels in sysfs" To: Fabrice Gasnier , thierry.reding@gmail.com, gottfried.haider@gmail.com Cc: stefan.wahren@i2se.com, hsweeten@visionengravers.com, loic.pallardy@st.com, broonie@kernel.org, gohai@sukzessiv.net, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-rpi-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-pwm@vger.kernel.org References: <1538400237-28766-1-git-send-email-fabrice.gasnier@st.com> <1538400237-28766-2-git-send-email-fabrice.gasnier@st.com> From: =?UTF-8?B?TWljaGFsIFZva8OhxI0=?= Message-ID: <156b0b28-a23a-b8f9-c8ef-67dfe31815ad@ysoft.com> Date: Mon, 1 Oct 2018 18:27:16 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ysoft.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 01 Oct 2018 16:27:19.1300 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 6d1b76a0-d735-4e20-5bd6-08d627bac252 X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: b5839965-430f-4be2-b282-d7a3149f2b37 X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM0PR04MB4658 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1.10.2018 15:23, Fabrice Gasnier wrote: > This reverts commit 7e5d1fd75c3dde9fc10c4472b9368089d1b81d00 ("pwm: Set > class for exported channels in sysfs") as it causes regression with > multiple pwm chip[1], when exporting a pwm channel (echo X > export): > > - ABI (Documentation/ABI/testing/sysfs-class-pwm) states pwmX should be > created in /sys/class/pwm/pwmchipN/pwmX > - Reverted patch causes new entry to be also created directly in > /sys/class/pwm/pwmX > - 1st time, exporting pwmX will create an entry in /sys/class/pwm/pwmX > - class attributes are added under pwmX folder, such as export, unexport > npwm, symlinks. This is wrong as it belongs to pwmchipN. It may cause > bad behavior and report wrong values. > - when another export happens on another pwmchip, it can't be created > (e.g. -EEXIST). This is causing the issue with multiple pwmchip. > > 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... > > This is also seen on other platform [2] > > [1] https://lkml.org/lkml/2018/9/25/713 > [2] https://lkml.org/lkml/2018/9/25/447 > > Signed-off-by: Fabrice Gasnier > Tested-by: Gottfried Haider Tested-by: Michal Vokáč > --- > drivers/pwm/sysfs.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c > index 7c71cdb..4726d43 100644 > --- a/drivers/pwm/sysfs.c > +++ b/drivers/pwm/sysfs.c > @@ -263,7 +263,6 @@ static int pwm_export_child(struct device *parent, struct pwm_device *pwm) > export->pwm = pwm; > mutex_init(&export->lock); > > - export->child.class = parent->class; > export->child.release = pwm_export_release; > export->child.parent = parent; > export->child.devt = MKDEV(0, 0); > From mboxrd@z Thu Jan 1 00:00:00 1970 From: michal.vokac@ysoft.com (=?UTF-8?B?TWljaGFsIFZva8OhxI0=?=) Date: Mon, 1 Oct 2018 18:27:16 +0200 Subject: [PATCH v2 1/2] Revert "pwm: Set class for exported channels in sysfs" In-Reply-To: <1538400237-28766-2-git-send-email-fabrice.gasnier@st.com> References: <1538400237-28766-1-git-send-email-fabrice.gasnier@st.com> <1538400237-28766-2-git-send-email-fabrice.gasnier@st.com> Message-ID: <156b0b28-a23a-b8f9-c8ef-67dfe31815ad@ysoft.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 1.10.2018 15:23, Fabrice Gasnier wrote: > This reverts commit 7e5d1fd75c3dde9fc10c4472b9368089d1b81d00 ("pwm: Set > class for exported channels in sysfs") as it causes regression with > multiple pwm chip[1], when exporting a pwm channel (echo X > export): > > - ABI (Documentation/ABI/testing/sysfs-class-pwm) states pwmX should be > created in /sys/class/pwm/pwmchipN/pwmX > - Reverted patch causes new entry to be also created directly in > /sys/class/pwm/pwmX > - 1st time, exporting pwmX will create an entry in /sys/class/pwm/pwmX > - class attributes are added under pwmX folder, such as export, unexport > npwm, symlinks. This is wrong as it belongs to pwmchipN. It may cause > bad behavior and report wrong values. > - when another export happens on another pwmchip, it can't be created > (e.g. -EEXIST). This is causing the issue with multiple pwmchip. > > 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... > > This is also seen on other platform [2] > > [1] https://lkml.org/lkml/2018/9/25/713 > [2] https://lkml.org/lkml/2018/9/25/447 > > Signed-off-by: Fabrice Gasnier > Tested-by: Gottfried Haider Tested-by: Michal Vok?? > --- > drivers/pwm/sysfs.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c > index 7c71cdb..4726d43 100644 > --- a/drivers/pwm/sysfs.c > +++ b/drivers/pwm/sysfs.c > @@ -263,7 +263,6 @@ static int pwm_export_child(struct device *parent, struct pwm_device *pwm) > export->pwm = pwm; > mutex_init(&export->lock); > > - export->child.class = parent->class; > export->child.release = pwm_export_release; > export->child.parent = parent; > export->child.devt = MKDEV(0, 0); >