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. - Hartmut _______________________________________________ linux-dvb mailing list linux-dvb@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
