Re: stv0903bab i2c-repeater question
2010/3/31 Andreas Regel andreas.re...@gmx.de: Hi Sergey, Am 31.03.2010 12:14, schrieb Sergey Mironov: Hello maillist! I am integrating frontend with dvb-demux driver of one device called mdemux. The frontend includes following parts: - stv0903bab demodulator - stv6110a tuner - lnbp21 power supply controller stv6110a is connected to i2c bus via stv0903's repeater. My question is about setting up i2c repeater frequency divider (I2CRPT register). stv0903 datasheet says that the speed of the i2c repeater obtained by dividing the internal chip frequency (that is, 135 MHz) budget.c driver uses value STV090x_RPTLEVEL_16 for this divider. But 135*10^6/16 is still too high to be valid i2c freq. Please explain where I'm wrong. Does the base frequency really equals to 135 Mhz? Thanks. The frequency divider in I2CRPT controls the speed of the I2C repeater HW unit inside the STV0903. The I2C clock itself has the same speed as the one that is used to access the STV0903. The repeater basically just routes the signals from one bus to the other and needs a higher internal frequency to do that properly. That is the frequency you set up with I2CRPT. Regards Andreas Thanks, Andreas! Of cause, different i2c bus frequencies would require some buffer inside repeater. But there is no information about such things. I've checked carefully and it seems that ENARPT_LEVEL actually defines repeater delay. -- Sergey -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
stv0903bab i2c-repeater question
Hello maillist! I am integrating frontend with dvb-demux driver of one device called mdemux. The frontend includes following parts: - stv0903bab demodulator - stv6110a tuner - lnbp21 power supply controller stv6110a is connected to i2c bus via stv0903's repeater. My question is about setting up i2c repeater frequency divider (I2CRPT register). stv0903 datasheet says that the speed of the i2c repeater obtained by dividing the internal chip frequency (that is, 135 MHz) budget.c driver uses value STV090x_RPTLEVEL_16 for this divider. But 135*10^6/16 is still too high to be valid i2c freq. Please explain where I'm wrong. Does the base frequency really equals to 135 Mhz? Thanks. -- Sergey -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: stv0903bab i2c-repeater question
Hi Sergey, Am 31.03.2010 12:14, schrieb Sergey Mironov: Hello maillist! I am integrating frontend with dvb-demux driver of one device called mdemux. The frontend includes following parts: - stv0903bab demodulator - stv6110a tuner - lnbp21 power supply controller stv6110a is connected to i2c bus via stv0903's repeater. My question is about setting up i2c repeater frequency divider (I2CRPT register). stv0903 datasheet says that the speed of the i2c repeater obtained by dividing the internal chip frequency (that is, 135 MHz) budget.c driver uses value STV090x_RPTLEVEL_16 for this divider. But 135*10^6/16 is still too high to be valid i2c freq. Please explain where I'm wrong. Does the base frequency really equals to 135 Mhz? Thanks. The frequency divider in I2CRPT controls the speed of the I2C repeater HW unit inside the STV0903. The I2C clock itself has the same speed as the one that is used to access the STV0903. The repeater basically just routes the signals from one bus to the other and needs a higher internal frequency to do that properly. That is the frequency you set up with I2CRPT. Regards Andreas -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html