From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from s3.sipsolutions.net ([5.9.151.49]:41154 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750955AbbBXULh (ORCPT ); Tue, 24 Feb 2015 15:11:37 -0500 Message-ID: <1424808692.2192.40.camel@sipsolutions.net> (sfid-20150224_211140_840201_9F2A0034) Subject: Re: [PATCH 1/1] nl80211: add NL80211_CMD_GET_TSF From: Johannes Berg To: Rohan Joyce Cc: linville@tuxdriver.com, linux-wireless@vger.kernel.org Date: Tue, 24 Feb 2015 21:11:32 +0100 In-Reply-To: <1424705885-20987-1-git-send-email-rojoyce.github@gmail.com> (sfid-20150223_163842_631527_DEEDB1C8) References: <1424701880.3075.0.camel@sipsolutions.net> <1424705885-20987-1-git-send-email-rojoyce.github@gmail.com> (sfid-20150223_163842_631527_DEEDB1C8) Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Mon, 2015-02-23 at 23:38 +0800, Rohan Joyce wrote: > Hi, > > The motivation for this patch is to assist using a WiiU Gamepad with Linux. > The WiiU Gamepad is an input device that also contains an LCD touchscreen, > speakers and a variety of sensors. The Gamepad connects to an access > point (usually the WiiU console itself, but it can be coerced to connect > to a properly configured hostap). The Gamepad provides five services over > UDP. Two of the services that are provided (audio and video streaming to > the device) use the TSF as a timestamp in the application layer. The > firmware on the Gamepad checks to make sure that incoming packets for > these services have timestamps within 1000us of its own internal clock, > which is synced to the TSF of the access point. Oh, right, I remember now. > At the moment, users who want to use this device have to manually apply > a kernel patch similar to that which was first posted to this list a year > ago. This patch is my attempt to implement the functionality using a more > conventional API and make it easier for end users. > > Should I include protocol implementation details specific to this device in > the documentation of the NL80211_CMD_GET_TSF command? Not necessarily, but some information about why this is needed would be good. I guess since this has no way of using something like 11v this really is the only chance. Note that you'll need to add a feature capability flag for this - many drivers, even ones based on mac80211, will not be able to implement this properly so relying only on the presence of the callback will not work properly. johannes