Re: [PATCH] video4linux: Push down the BKL

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From: Devin Heitmueller

Subject: Re: [PATCH] video4linux: Push down the BKL

Date: Tuesday, May 27, 2008 - 5:46 pm

Hello Andy,

On Tue, May 27, 2008 at 7:48 PM, Andy Walls <awalls@radix.net> wrote:
quoted text> MythTV's mythbackend can open both sides of the card at the same time
> and the cx18 driver supports it.  On my HVR-1600, MythTV may have the
> digital side of the card open pulling EPG data off of the ATSC
> broadcasts, when I open up the MythTV frontend and start watching live
> TV on the analog side of the card.  MythTV also supports
> Picture-in-Picture using both the analog and digital parts of the
> HVR-1600.

In this case, what you see as a 'feature' in MythTV is actually a
problem in our case.  While the HVR-1600 can support this scenario,
the HVR-950 can only use one or the other (the em28xx chip uses GPIOs
to enable the demodulator and presumably you should never have both
demodulators enabled at the same time).  Because of this we need a
lock.  If MythTV only opened one device or the other at a time, we
could put the lock on the open() call, but since MythTV opens both
simultaneously even though it may only be using one, we would need a
much more granular lock.

Certainly I'm not blaming MythTV for this behavior, but it will make
the locking much more complicated in some hybrid devices.

-- 
Devin J. Heitmueller
http://www.devinheitmueller.com
AIM: devinheitmueller
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Messages in current thread:

[PATCH] video4linux: Push down the BKL, Alan Cox, (Thu May 22, 2:37 pm)

Re: [PATCH] video4linux: Push down the BKL, Andy Walls, (Thu May 22, 7:08 pm)

Re: [PATCH] video4linux: Push down the BKL, Hans Verkuil, (Thu May 22, 11:16 pm)

Re: [PATCH] video4linux: Push down the BKL, Hans Verkuil, (Thu May 22, 11:28 pm)

Re: [PATCH] video4linux: Push down the BKL, Alan Cox, (Fri May 23, 2:09 am)

Re: [PATCH] video4linux: Push down the BKL , Jonathan Corbet, (Fri May 23, 6:56 am)

Re: [PATCH] video4linux: Push down the BKL, Alan Cox, (Fri May 23, 8:39 am)

Re: [PATCH] video4linux: Push down the BKL , Jonathan Corbet, (Fri May 23, 9:09 am)

Re: [PATCH] video4linux: Push down the BKL, Alan Cox, (Fri May 23, 11:58 am)

Re: [PATCH] video4linux: Push down the BKL, Hans Verkuil, (Fri May 23, 12:05 pm)

Re: [PATCH] video4linux: Push down the BKL, Mike Isely, (Sun May 25, 4:46 pm)

Re: [PATCH] video4linux: Push down the BKL, Mauro Carvalho Chehab, (Mon May 26, 9:34 am)

Re: [PATCH] video4linux: Push down the BKL, Mauro Carvalho Chehab, (Mon May 26, 9:39 am)

Re: [PATCH] video4linux: Push down the BKL, Hans Verkuil, (Mon May 26, 9:46 am)

Re: [PATCH] video4linux: Push down the BKL, Mauro Carvalho Chehab, (Mon May 26, 9:59 am)

Re: [PATCH] video4linux: Push down the BKL, Alan Cox, (Mon May 26, 1:23 pm)

Re: [PATCH] video4linux: Push down the BKL, Mauro Carvalho Chehab, (Mon May 26, 2:10 pm)

Re: [PATCH] video4linux: Push down the BKL, Mauro Carvalho Chehab, (Mon May 26, 2:14 pm)

Re: [PATCH] video4linux: Push down the BKL, Alan Cox, (Mon May 26, 3:01 pm)

Re: [PATCH] video4linux: Push down the BKL, Mauro Carvalho Chehab, (Tue May 27, 6:10 am)

Re: [PATCH] video4linux: Push down the BKL, Jonathan Corbet, (Tue May 27, 8:41 am)

Re: [PATCH] video4linux: Push down the BKL, Mauro Carvalho Chehab, (Tue May 27, 9:31 am)

Re: [PATCH] video4linux: Push down the BKL, Jonathan Corbet, (Tue May 27, 9:37 am)

Re: [PATCH] video4linux: Push down the BKL, Alan Cox, (Tue May 27, 11:14 am)

Re: [PATCH] video4linux: Push down the BKL, Mauro Carvalho Chehab, (Tue May 27, 11:59 am)

Re: [PATCH] video4linux: Push down the BKL, Devin Heitmueller, (Tue May 27, 12:26 pm)

Re: [PATCH] video4linux: Push down the BKL, Arjan van de Ven, (Tue May 27, 12:50 pm)

Re: [PATCH] video4linux: Push down the BKL, Mauro Carvalho Chehab, (Tue May 27, 1:24 pm)

Re: [PATCH] video4linux: Push down the BKL, Mauro Carvalho Chehab, (Tue May 27, 2:00 pm)

Re: [PATCH] video4linux: Push down the BKL, Devin Heitmueller, (Tue May 27, 2:22 pm)

Re: [PATCH] video4linux: Push down the BKL, Andy Walls, (Tue May 27, 4:48 pm)

Re: [PATCH] video4linux: Push down the BKL, Devin Heitmueller, (Tue May 27, 5:46 pm)

Re: [PATCH] video4linux: Push down the BKL, Andy Walls, (Tue May 27, 7:37 pm)

Re: [PATCH] video4linux: Push down the BKL, Devin Heitmueller, (Tue May 27, 7:47 pm)

Re: [PATCH] video4linux: Push down the BKL, Hans Verkuil, (Tue May 27, 11:13 pm)

Re: [PATCH] video4linux: Push down the BKL, Alan Cox, (Wed May 28, 1:34 am)