[linux-dvb] Typhoon (KNC1 ?) COLD BOOT problem

Johannes Stezenbach js at linuxtv.org
Sat Dec 10 21:14:05 CET 2005

On Mon, Dec 05, 2005, Michael Rickmann wrote:
> I have an old Typhoon DVB-S card which has the same cold boot problem as the 
> KNC1 which Chris Dietrich reported about in November  
> ( http://www.linuxtv.org/pipermail/linux-dvb/2005-November/005804.html ).
> The explanation for my problem seems relatively straightforward. After a cold 
> boot as defined above the stv0299 does not respond at the 
> SAA7146_I2C_BUS_BIT_RATE_120 used by the current driver.
> When I use SAA7146_I2C_BUS_BIT_RATE_3200 as the Metzler driver does the 
> frontend loads correctly but szap does not get a lock. I have also tried 
> SAA7146_I2C_BUS_BIT_RATE_240 and SAA7146_I2C_BUS_BIT_RATE_480.
> With these the Typhoon cold boots correctly and works properly.
> It would be valuable to know wether this is a general problem of KNC1-S and 
> old Typhoon-S cards or wether Chris and I have some odd problems.
> To find out wether my measure works replace SAA7146_I2C_BUS_BIT_RATE_120 in
> ../linux/drivers/media/dvb/ttpci/budget-core.c, line 384 by e.g. 
> SAA7146_I2C_BUS_BIT_RATE_480 or apply attached patch.

The stv0299 data sheet says that while the device is in standby mode,
the I2C bus speed has to be limited to F_CLK_IN/10, which usually is
400kHz. SAA7146_I2C_BUS_BIT_RATE_120 is PCI_CLK/120 = 275kHz. So it
should work.
The stv0299 normally starts up in normal mode, but can
be made to start up in standby by a strap pin.

Can you try if it is sufficient to lower the I2C bus speed
just for probing, and increase it later?

e.g. in budget_av_attach():
	saa7146_i2c_adapter_prepare(dev, NULL, SAA7146_I2C_BUS_BIT_RATE_480);
	saa7146_i2c_adapter_prepare(dev, NULL, SAA7146_I2C_BUS_BIT_RATE_120);

(slightly hackish, but OK for testing; if it works we should add a
saa7146_i2c_set_speed() API; maybe need also handle wakeup after

But I'm not sure if this kind of optimization is worth it, maybe I
should just merge your patch. Opinions?


More information about the linux-dvb mailing list