[linux-dvb] Re: timing in dvb-kernel

[Jeremy Hall <jhall@maoz.com>]

Hi,

yes this fixed my problems.  Will this be more reliable than the DVB tree 
or the same? (the DVB code sometimes misfires and the wrong LNB is 
selected)

What must be done to get this change into the dvb-kernel tree? What are 
the consequences of changing [2] why has it been ignored?

If people want to support echostar switches in their applications need to 
be able to switch voltage in under 8ms, and they're not going to want to 
apply this patch to the tree.

_J

In the new year, Oliver Endriss wrote:
> On Monday 24 November 2003 15:28, Jeremy Hall wrote:
> > Per some suggestions, I opted to try the dvb-kernel tree, but found that 
> > timing is worse in the dvb-kernel.
> > 
> > I have requirements to be able to change voltage from h to v in under 8ms 
> > consistently, and can successfully achieve this with the DVB code, but 
> > dvb-kernel seems not able to do this.  Do you have suggestions on what I 
> > might try to improve the latency?
> 
> This requires two modifications:
> [1] I committed a change to 'dvb-kernel' which increases speed of the
>     I2C bus for *full-featured* cards to 275 kHz (same value as in DVB).
>     Please update file av7110.c from dvb-kernel CVS.
> 
> [2] Apply the following patch to saa7146_i2c.c:
> 
> -----------------  snip  ----------------------------
> diff -p -u -r1.26 saa7146_i2c.c
> --- saa7146_i2c.c	14 Nov 2003 11:42:04 -0000	1.26
> +++ saa7146_i2c.c	25 Nov 2003 03:29:29 -0000
> @@ -301,7 +301,7 @@ int saa7146_i2c_transfer(struct saa7146_
>  		goto out;
>  	}
>  
> -        if (count > 3) short_delay = 1;
> +        short_delay = 1; // OE test
>    
>  	do {
>  		/* reset the i2c-device if necessary */
> -----------------  snip  ----------------------------
> 
> Note that without [2] modification [1] is almost useless,
> because each I2C access causes a delay of 10..20ms.
> I suggested several times to improve this but I was ignored...
> 
> Oliver
> 
> 
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