From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.kapsi.fi ([217.30.184.167]:36517 "EHLO mail.kapsi.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933483AbZJLWcA (ORCPT ); Mon, 12 Oct 2009 18:32:00 -0400 Message-ID: <4AD3AE34.6020305@iki.fi> Date: Tue, 13 Oct 2009 01:31:16 +0300 From: Antti Palosaari MIME-Version: 1.0 To: Devin Heitmueller CC: Linux Media Mailing List Subject: Re: em28xx mode switching References: <829197380910121512y62a90cdcs49a0aa9606e8a588@mail.gmail.com> In-Reply-To: <829197380910121512y62a90cdcs49a0aa9606e8a588@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: On 10/13/2009 01:12 AM, Devin Heitmueller wrote: > I was debugging an issue on a user's hybrid board, when I realized > that we are switching the em28xx mode whenever we start and stop dvb > streaming. We already have the ts_bus_ctrl callback implemented which > puts the device into digital mode and puts it back into suspend > whenever the frontend is opened/closed. > > This call seems redundant, and in fact can cause problems if the > dvb_gpio definition strobes the reset pin, as it can put the driver > out of sync with the demodulator's state (in fact this is what I ran > into with the zl10353 - the reset pin got strobed when the streaming > was started but the demod driver's init() routine was not being run > because it already ran when the frontend was originally opened). > > The only case I can think of where toggling the device mode when > starting/stopping dvb streaming might be useful is if we wanted to > support being able to do an analog tune while the dvb frontend was > still open but not streaming. However, this seems like this could > expose all sorts of bugs, and I think the locking would have to be > significantly reworked if this were a design goal. > > Thoughts anybody? > > Devin I ran this same trap few weeks ago when adding Reddo DVB-C USB Box support to em28xx :) Anyhow, since it is dvb only device I decided to switch from .dvb_gpio to .tuner_gpio to fix the problem. I haven't pull requested it yet. http://linuxtv.org/hg/~anttip/reddo-dvb-c/rev/38f946af568f Antti -- http://palosaari.fi/