From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]:59741 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752038Ab2LWNoi convert rfc822-to-8bit (ORCPT ); Sun, 23 Dec 2012 08:44:38 -0500 Date: Sun, 23 Dec 2012 11:44:13 -0200 From: Mauro Carvalho Chehab To: Frank =?UTF-8?B?U2Now6RmZXI=?= Cc: linux-media@vger.kernel.org Subject: Re: [PATCH v2 21/21] em28xx: add module parameter for selection of the preferred USB transfer type Message-ID: <20121223114413.6d2c7dc1@redhat.com> In-Reply-To: <1352398313-3698-22-git-send-email-fschaefer.oss@googlemail.com> References: <1352398313-3698-1-git-send-email-fschaefer.oss@googlemail.com> <1352398313-3698-22-git-send-email-fschaefer.oss@googlemail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-media-owner@vger.kernel.org List-ID: Hi Frank, Em Thu, 8 Nov 2012 20:11:53 +0200 Frank Schäfer escreveu: > By default, isoc transfers are used if possible. > With the new module parameter, bulk can be selected as the > preferred USB transfer type. I did some tests yesterday with prefer_bulk. IMHO, webcams should select bulk mode by default, as this allows more than one camera to work at the same time (I tested yesterday with 3 Silvercrest ones on my notebook). With ISOC transfers, the core won't let it to happen, as a single camera reserves 51% of the max allowed isoc traffic. > Signed-off-by: Frank Schäfer > --- > drivers/media/usb/em28xx/em28xx-cards.c | 11 +++++++++-- > 1 Datei geändert, 9 Zeilen hinzugefügt(+), 2 Zeilen entfernt(-) > > diff --git a/drivers/media/usb/em28xx/em28xx-cards.c b/drivers/media/usb/em28xx/em28xx-cards.c > index a9344f0..7f5b303 100644 > --- a/drivers/media/usb/em28xx/em28xx-cards.c > +++ b/drivers/media/usb/em28xx/em28xx-cards.c > @@ -61,6 +61,11 @@ static unsigned int card[] = {[0 ... (EM28XX_MAXBOARDS - 1)] = UNSET }; > module_param_array(card, int, NULL, 0444); > MODULE_PARM_DESC(card, "card type"); > > +static unsigned int prefer_bulk; > +module_param(prefer_bulk, int, 0644); This needs to be changed to 0444, as prefer_bulk doesn't allow changing it dynamically, as the test is done during device probe, not at stream on. Regards, Mauro