linux-kernel - Re: [PATCH] DVB Satellite Channel Routing support for DVB-S

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Date:	Mon, 10 Jan 2011 18:28:39 +0100
From:	Oliver Endriss <o.endriss@....de>
To:	Andreas Oberritter <obi@...uxtv.org>
Cc:	Thomas Schlöter <thomas.schloeter@....net>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] DVB Satellite Channel Routing support for DVB-S

On Monday 10 January 2011 16:54:14 Andreas Oberritter wrote:
> On 01/10/2011 04:07 PM, Thomas Schlöter wrote:
> >>> I decided this should be supported by the kernel frontend code as it is impossible to send that special DiSEqC / voltage sequence from userspace.
> >>
> >> Why do you think that's impossible? There's a userspace implementation
> >> in Enigma2.
> > 
> > I think the kernel implementation would be superior for two reasons:
> > - There are some timing requirements regarding the 14/18V transitions and the DiSEqC message which could perform better directly from the frontend code,
> 
> Unless there's proof, I won't believe that. We're not talking about
> nanoseconds, but milliseconds, and it's about setting registers of slow
> I2C devices. The same timing requirements are valid for each and every
> backwards compatible DiSEqC sequence, which is the most common setting.
> 
> > - In many TV recording applications there is no support for SCR and it would be harder to implement in these. For VDR, there is a patch which is difficult to configure and has some technical limitations. In MythTV and XMBC I could not find any support for SCR. Their Wiki pages or forums say, that there are no plans for Unicable support as it would take huge changes.
> 
> Many of these applications didn't or don't support DiSEqC 1.1
> (uncommittted switches) or DiSEqC 1.2 (rotor commands) or USALS. Still,
> we don't put this logic into the kernel to make their life easier. Don't
> add unneeded complexity to the kernel.
> 
> Of course, one could decide to start a reusable library to take care of
> that stuff. Honestly, I don't know whether such a library exists today.
> 
> If you find the patch was simple enough to be applied to the kernel, it
> must be as simple to patch your favourite application, even in a
> platform independent way (not taking into account the required changes
> to the UI, which have to be done anyway).

Ack, this stuff should be implemented as a userspace library.
(Btw, there is an experimental unicable patch for VDR.)

CU
Oliver

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