Re: em28xx mode switching

[Antti Palosaari <crope@iki.fi>]

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/