From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755918AbcHXLuH (ORCPT ); Wed, 24 Aug 2016 07:50:07 -0400 Received: from smtp.nue.novell.com ([195.135.221.5]:43365 "EHLO smtp.nue.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751168AbcHXLuF (ORCPT ); Wed, 24 Aug 2016 07:50:05 -0400 Subject: Re: [PATCH V3] leds: trigger: Introduce an USB port trigger To: =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= References: <20160823220404.9887-1-zajec5@gmail.com> Cc: Richard Purdie , Jacek Anaszewski , Felipe Balbi , Peter Chen , "linux-usb@vger.kernel.org" , =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= , Jonathan Corbet , Ezequiel Garcia , Boris Brezillon , Geert Uytterhoeven , Stephan Linz , "open list:DOCUMENTATION" , open list , "open list:LED SUBSYSTEM" From: Matthias Brugger Message-ID: <6beb372b-cc66-0d7b-0111-19a1217f7833@suse.com> Date: Wed, 24 Aug 2016 13:27:50 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24/08/16 13:02, Rafał Miłecki wrote: > On 24 August 2016 at 12:49, Matthias Brugger wrote: >> On 24/08/16 00:03, Rafał Miłecki wrote: [...] >>> +static int usbport_trig_notify(struct notifier_block *nb, unsigned long >>> action, >>> + void *data) >>> +{ >>> + struct usbport_trig_data *usbport_data = >>> + container_of(nb, struct usbport_trig_data, nb); >>> + struct led_classdev *led_cdev = usbport_data->led_cdev; >>> + >>> + switch (action) { >>> + case USB_DEVICE_ADD: >>> + if (usbport_trig_usb_dev_observed(usbport_data, data)) { >> >> >> Maybe we should switch this and fist see if the usbport is observed before >> evaluating the action. Also cast data to "struct usb_device *" to make that >> clear. > > I'm aware there is one duplicated line of code, I did to first > evaluate very quick test (checking unsigned long value), then iterate > over ports & keep only 1 switch block. I could move > usbport_trig_usb_dev_observed call up, but it would be executed for > other actions as well (currently just USB_BUS_ADD and USB_BUS_REMOVE). > Ok. I'm a USB noop but from my understanding the notifier is only called when a device or a hub gets added/removed. So this shouldn't happen that much. Therefor it has no impact if we check if the usb device is in the observer list for all actions. > >>> + if (usbport_data->count++ == 0) >> >> >> I'm a bit puzzled. I think: >> if (++usbport_data->count > 0) >> makes this more consistent with the remove case. > > Your condition would be always true (as we don't use negative > numbers). The point is to enable LED only if it was disabled before. > So I need to increase counter unconditionally but enable LED only if > initial value (before increasing it) was 0. > Got it. My personal opinion is, that adding one line for incrementing/decrementing the counter would help to make this crystal-clear to everyone (at least to me :) Cheers, Matthias > >>> +module_init(usbport_trig_init); >>> +module_exit(usbport_trig_exit); >>> + >>> +MODULE_AUTHOR("Rafał Miłecki "); >> >> >> Nit: rafal@milecki.pl > > Oops, thanks! >