[linux-dvb] PATCH: Generic FE_DISHNETWORK_SEND_LEGACY_CMD support

Johannes Stezenbach js at linuxtv.org
Tue Sep 27 00:02:50 CEST 2005


On Mon, Sep 26, 2005 NooneImportant wrote:
> On 9/26/05, Johannes Stezenbach js-at-linuxtv.org
> > Could you please test if the SAA7146_I2C_SHORT_DELAY flag
> > fixes the dishnetwork emulation for you stv0299 budget card?
> > (Because I don't see why set_voltage() should be slower on
> > stv0299 than on other frontends.)
> 
> I don't have a budget card in my system right now, so I can't test it
> at the moment.
> As I recall the problem was these two commands at the top of
> stv0299_set_voltage:
>         reg0x08 = stv0299_readreg (state, 0x08);
>         reg0x0c = stv0299_readreg (state, 0x0c);
> 
> The time it took for them to return was often longer than 8ms on my
> Nova-S card (but not on my Nexus-S).  Is this something that
> SAA7146_I2C_SHORT_DELAY could fix?  I'll try it again when I get a
> chance though.

Yes, these two i2c messages whould take less than 8ms
with SAA7146_I2C_SHORT_DELAY.

> I should mention that even with the tuned code in stv0299.c, my budget
> card only manages to successfully control the switch 80% of the time. 
> The problem appears to be (from examining with an o-scope) that the
> voltage control is just not very precise on that card (lots of noise
> on the output as it switches compared to the Nexus-S, which is very
> clean).  I don't think  there is anything that can be done about that
> though.

Hm, the card should be able two switch the voltage fast enough to
generate a 22kHz signal...

Johannes



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