From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.kapsi.fi ([217.30.184.167]:49504 "EHLO mail.kapsi.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750858AbZIJQtA (ORCPT ); Thu, 10 Sep 2009 12:49:00 -0400 Message-ID: <4AA92DF6.80107@iki.fi> Date: Thu, 10 Sep 2009 19:48:54 +0300 From: Antti Palosaari MIME-Version: 1.0 To: Devin Heitmueller CC: "Aleksandr V. Piskunov" , Markus Rechberger , Clinton Meyer , Linux Media Subject: Re: LinuxTV firmware blocks all wireless connections / traffic References: <62013cda0909091443g72ebdf1bge3994b545a86c854@mail.gmail.com> <20090910124549.GA18426@moon> <20090910124807.GB18426@moon> <4AA8FB2F.2040504@iki.fi> <20090910134139.GA20149@moon> <4AA9038B.8090404@iki.fi> <4AA911B6.2040301@iki.fi> <829197380909100826i3e2f8315yd6a0258f38a6c7b9@mail.gmail.com> <4AA92160.5080200@iki.fi> <829197380909100912xdb34da0s55587f6fe9c0f1d5@mail.gmail.com> In-Reply-To: <829197380909100912xdb34da0s55587f6fe9c0f1d5@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Devin Heitmueller wrote: > On Thu, Sep 10, 2009 at 11:55 AM, Antti Palosaari wrote: >> Devin Heitmueller wrote: >>> The URB size is something that varies on a device-by-device basis, >>> depending on the bridge chipset. There really is no >>> "one-size-fits-all" value you can assume. >> I doubt no. I tested last week rather many USB chips and all I tested >> allowed to set it as x188 or x512 bytes. If it is set something than chip >> does not like it will give errors or packets that are not as large as >> requested. You can test that easily, look dvb-usb module debug uxfer and use >> powertop. >> >>> I usually take a look at a USB trace of the device under Windows, and >>> then use the same value. >> I have seen logs where different sizes of urbs used even same chip. > > Yes, the URB size can change depending on who wrote the driver, or > what the required throughput is. For example, the em28xx has a > different URB size depending on whether the target application is > 19Mbps ATSC or 38Mbps QAM. That just reinforces what I'm saying - the > size selected in many cases is determined by the requirements of the > chipset. Yes thats just what I tried to say for. Look my previous thread where all currently sizes are listed. We need to define suitable values that are used. For example USB2.0 DVB-C, DVB-T, ATSC and same values for USB1.1 too. And stream size can vary much depending used transmission parameters too but I think such kind resolution logic is not needed. Currently there is almost everything between 512 to 65k used for DVB-T that makes huge difference to load device causing. Does anyone know if there is some table which says what are good USB transmission parameters for each bandwidth needed? > Making it some multiple of 188 for DVB is logical since that's the > MPEG packet size. That seems pretty common in the bridges I have > worked with. > > Devin Antti -- http://palosaari.fi/