On Saturday 18 November 2006 10:07, e9hack wrote: > Andrew de Quincey wrote: > > On Sunday 08 October 2006 08:43, e9hack wrote: > >> Hi, > >> > >> I've problems with the TT-C2300 DVB-C card and qam256 modulated > >> channels. After switching to a qam256 channel, the card needs between > >> 0.5 and 1 hour to get the lock. Possible it is a problem of the reduced > >> i2c bus speed. If the stv0297 is accessed with a higher i2c bus speed, > >> the card gets the lock within a few seconds like qam64. I've attach a > >> patch, which does reduce the i2c bus speed for the tuner only. I've > >> measured the time between 'after tuning' and 'start waiting for the agc > >> lock' in stv0297_set_frontend(). Without the patch it needs 470ms and > >> with the patch 60ms. This is a little bit strange, because the factor of > >> the speed changing is two. Possible, there is a bug in the spec of the > >> saa7146. > > > > Looks sensible to me; no point slowing the demod access just for the > > tuner. Will commit once you send me a signed off by line for it... > > The i2c-bus speed problem is already fixed by > http://linuxtv.org/hg/v4l-dvb?cs=4a4213dbb9b8;style=gitweb. It was a > problem of the max loop count in saa7146_i2c_writeout(). The saa7146 can > transfer three bytes over the i2c-bus with one upload. The TT-C2300 uses > a reduced i2c speed of 137.5kHz. This is necessary, because the pll chip > (tda6405) has a max i2c-speed of 150kHz. The time for a transfer of > three bytes is ca. 200us. With the old max loop count of 20, I got an > additional delay of 1ms for the half of the transfers. This has > increased the initialization time of the stv0297. > > I think. it isn't necessary to commit this patch. Cool! Sorry - I was away for a bit and missed that. No need to commit as you say.. _______________________________________________ linux-dvb mailing list linux-dvb@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
