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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,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 9EE82C433E0 for ; Thu, 7 Jan 2021 09:17:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5873F2312E for ; Thu, 7 Jan 2021 09:17:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727111AbhAGJQ7 (ORCPT ); Thu, 7 Jan 2021 04:16:59 -0500 Received: from mail.kernel.org ([198.145.29.99]:44378 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726326AbhAGJQ6 (ORCPT ); Thu, 7 Jan 2021 04:16:58 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id B09AF2312E; Thu, 7 Jan 2021 09:16:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1610010978; bh=OEOK2cLcu8Rs1Ti+sJvJCut6L+tJsNZ58wiR33kb3B8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=kZi7+ScM3q5aj1jeNkMlp04Pg7wVx4ShJ0zoNzuUe1M+3AWWO+LHvjKnfulIwiklW Gl59u+rb8kYcJwepxbaY9OlVmBjdfFcaYqPwxuv68JXXdPhTR7eAy9l5JwSWMaFVBF pfTPuEZ6LU6QJp9JY6u3te9xiwcqOKyTVlqS6wiw= Date: Thu, 7 Jan 2021 10:17:38 +0100 From: Greg KH To: Prashant Malani Cc: linux-usb@vger.kernel.org, Heikki Krogerus , Benson Leung , open list Subject: Re: [PATCH] usb: typec: Send uevent for num_altmodes update Message-ID: References: <20210107034904.4112029-1-pmalani@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210107034904.4112029-1-pmalani@chromium.org> Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Wed, Jan 06, 2021 at 07:49:04PM -0800, Prashant Malani wrote: > Generate a change uevent when the "number_of_alternate_modes" sysfs file > for partners and plugs is updated by a port driver. > > Cc: Heikki Krogerus > Cc: Benson Leung > Signed-off-by: Prashant Malani > --- > drivers/usb/typec/class.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/usb/typec/class.c b/drivers/usb/typec/class.c > index ebfd3113a9a8..8f77669f9cf4 100644 > --- a/drivers/usb/typec/class.c > +++ b/drivers/usb/typec/class.c > @@ -766,6 +766,7 @@ int typec_partner_set_num_altmodes(struct typec_partner *partner, int num_altmod > return ret; > > sysfs_notify(&partner->dev.kobj, NULL, "number_of_alternate_modes"); > + kobject_uevent(&partner->dev.kobj, KOBJ_CHANGE); Shouldn't the sysfs_notify() handle the "something has changed" logic good enough for userspace, as obviously someone is polling on the thing (otherwise we wouldn't be calling sysfs_notify...) The kobject itself hasn't "changed", but rather an individual attribute has changed. We don't want to create uevents for every individual sysfs attribute changing values, do we? What is preventing a normal "monitor the sysfs file" logic from working here for anyone who wants to know that the alternate modes have changed? thanks, greg k-h