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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 5EBB8C47423 for ; Fri, 2 Oct 2020 13:35:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2BFAF21D92 for ; Fri, 2 Oct 2020 13:35:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601645717; bh=mxQMcNr/+Vu2r+EP+HFk6PZXPQQQiTbn+HkTIGgZC40=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=LWfx84ljA1/c/+9pWk3yD94ZA+cJ2Mmr4sTKHJcuSqV23qt9I86mV/YG29WQeDbT4 kT1ClkhaXVLCIrf/K3KE2YVpm6GiCwnPA6wLfwEoMdS5jrh2/gKUQZ3KFtxtuOa4xg Yu2XnYDE/8ZEKXRXvRjh9HLjHxPPARDWvan2/jUs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387925AbgJBNfQ (ORCPT ); Fri, 2 Oct 2020 09:35:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:40256 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726017AbgJBNfN (ORCPT ); Fri, 2 Oct 2020 09:35:13 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 24B2321D94; Fri, 2 Oct 2020 13:35:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601645712; bh=mxQMcNr/+Vu2r+EP+HFk6PZXPQQQiTbn+HkTIGgZC40=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=dTDIHST4UTPaG8gSCkTfDHGXP7GMQKJZ0acYdFC2iIzew0J+nkxjLJ4SnlNyg+3hc hYoreOrxhNqFShi9vBrc+ivmutZXpOXmzWPbgQXit41Ri+saUSVSX9JheSg9/FUeNC pcvqizQsl7AOkOFgw2kDQUy4ZXS1ooc8AXeBhdtg= Date: Fri, 2 Oct 2020 15:35:12 +0200 From: Greg Kroah-Hartman To: Lars Poeschel Cc: Thierry Reding , Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= , Lee Jones , "open list:PWM SUBSYSTEM" , open list Subject: Re: [PATCH 1/2] pwm: sysfs: Set class on pwm devices Message-ID: <20201002133512.GB3386034@kroah.com> References: <20201002123048.3073128-1-poeschel@lemonage.de> <20201002124616.GB3348424@kroah.com> <20201002130844.udikqwzspp6zlyhh@lem-wkst-02.lemonage> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201002130844.udikqwzspp6zlyhh@lem-wkst-02.lemonage> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 02, 2020 at 03:08:44PM +0200, Lars Poeschel wrote: > On Fri, Oct 02, 2020 at 02:46:16PM +0200, Greg Kroah-Hartman wrote: > > On Fri, Oct 02, 2020 at 02:30:47PM +0200, poeschel@lemonage.de wrote: > > > From: Lars Poeschel > > > > > > This adds a class to exported pwm devices. > > > Exporting a pwm through sysfs did not yield udev events. The > > > dev_uevent_filter function does filter-out devices without a bus or > > > class. > > > This was already addressed in commit > > > commit 7e5d1fd75c3d ("pwm: Set class for exported channels in sysfs") > > > but this did cause problems and the commit got reverted with > > > commit c289d6625237 ("Revert "pwm: Set class for exported channels in > > > sysfs"") > > > Problem with the previous approach was, that there is a clash if we have > > > multiple pwmchips: > > > echo 0 > pwmchip0/export > > > echo 0 > pwmchip1/export > > > would both export /sys/class/pwm/pwm0 . > > > > > > Now this patch changes the sysfs interface. We do include the pwmchip > > > number into the pwm directory that gets exported. > > > With the example above we get: > > > /sys/class/pwm/pwm-0-0 > > > /sys/class/pwm/pwm-1-0 > > > We maintain ABI backward compatibility through symlinks. > > > /sys/class/pwm/pwmchip0/pwm0 > > > /sys/class/pwm/pwmchip1/pwm0 > > > are now symbolic links to the new names. > > > > > > Cc: Greg Kroah-Hartman > > > Signed-off-by: Lars Poeschel > > > --- > > > drivers/pwm/sysfs.c | 57 +++++++++++++++++++++++++++++++++++++-------- > > > 1 file changed, 47 insertions(+), 10 deletions(-) > > > > > > diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c > > > index 449dbc0f49ed..c708da17a857 100644 > > > --- a/drivers/pwm/sysfs.c > > > +++ b/drivers/pwm/sysfs.c > > > @@ -240,8 +240,10 @@ static void pwm_export_release(struct device *child) > > > > > > static int pwm_export_child(struct device *parent, struct pwm_device *pwm) > > > { > > > + struct pwm_chip *chip = dev_get_drvdata(parent); > > > struct pwm_export *export; > > > char *pwm_prop[2]; > > > + char *link_name; > > > int ret; > > > > > > if (test_and_set_bit(PWMF_EXPORTED, &pwm->flags)) > > > @@ -256,25 +258,39 @@ 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); > > > export->child.groups = pwm_groups; > > > - dev_set_name(&export->child, "pwm%u", pwm->hwpwm); > > > + dev_set_name(&export->child, "pwm-%u-%u", chip->base, pwm->hwpwm); > > > > > > ret = device_register(&export->child); > > > - if (ret) { > > > - clear_bit(PWMF_EXPORTED, &pwm->flags); > > > - put_device(&export->child); > > > - export = NULL; > > > - return ret; > > > + if (ret) > > > + goto error; > > > + > > > + link_name = kasprintf(GFP_KERNEL, "pwm%u", pwm->hwpwm); > > > + if (link_name == NULL) { > > > + ret = -ENOMEM; > > > + goto dev_unregister; > > > } > > > - pwm_prop[0] = kasprintf(GFP_KERNEL, "EXPORT=pwm%u", pwm->hwpwm); > > > + > > > + pwm_prop[0] = kasprintf(GFP_KERNEL, "EXPORT=%s", > > > + export->child.kobj.name); > > > pwm_prop[1] = NULL; > > > kobject_uevent_env(&parent->kobj, KOBJ_CHANGE, pwm_prop); > > > > Do you still need to do this by hand? Why can't this uevent field > > belong to the class and have it create this for you automatically when > > the device is added? > > I did not add this with my patch, it was there before and I wonder, what > purpose it served, since the uevent was filtered because there was no > class there. > Now we have a class and now it works and this is what happens: > > /sys/class/pwm# echo 0 > pwmchip1/export > KERNEL[2111.952725] add /devices/platform/ocp/48302000.epwmss/48302200.pwm/pwm/pwmchip1/pwm-1-0 (pwm) > ACTION=add > DEVPATH=/devices/platform/ocp/48302000.epwmss/48302200.pwm/pwm/pwmchip1/pwm-1-0 > SEQNUM=1546 > SUBSYSTEM=pwm > > KERNEL[2111.955155] change /devices/platform/ocp/48302000.epwmss/48302200.pwm/pwm/pwmchip1 (pwm) > ACTION=change > DEVPATH=/devices/platform/ocp/48302000.epwmss/48302200.pwm/pwm/pwmchip1 > EXPORT=pwm-1-0 > SEQNUM=1547 > SUBSYSTEM=pwm > > The first event is the event from device_register. It informs us that we > now have a new pwm-1-0. Nice. > The second is the event done here "by hand". It informs us, that > pwmchip1 changed. It has a new export now. For me personally this is not > needed, but also I don't think it is wrong. > You decide! If the uevent was being filtered out anyway, and never sent, then let's just drop the thing as there is nothing to keep backwards compatible. thanks, greg k-h