I think 0x34 is the HDMI framer.
On Thu, Jan 2, 2014 at 10:58 AM, Robert Nelson <[email protected]>wrote: > On Thu, Jan 2, 2014 at 10:27 AM, Robert Nelson <[email protected]> > wrote: > > On Thu, Jan 2, 2014 at 10:11 AM, Robert Ianovich <[email protected]> > wrote: > >> The question is why can't be accessed regularly from user space by > reading > >> /dev/i2c-0 bus? > >> The I2C buses and devices can't be owned exclusively even by kernel due > to > >> I2C architecture, so as far as the bus is free, anyone should > read/write to > >> any address. > >> > >> I have worked on many industrial boards considerably bigger than BBB > >> (WindRiver kernel) and all devices with I2C for maintenance (RapidIO, > DSP, > >> MAC/PHY, etc) are accessible. > >> > >> Why on BeagleBone the addresses of HDMI framer, PMIC and onboard EE are > >> intentionally blocked by driver ? > >> Or why the DRM driver is written that way? > > > > Well the hdmi/edid is the easly one.. As the beaglebone dose not have > > direct access to that bus, take look at page 10: > > > > https://github.com/CircuitCo/BeagleBone-Black/blob/master/BBB_SCH.pdf > > > > Thus we need to query the TDA19988 device thru drm for the edid... > > > > As far as PMIC/EE are registered by the dts in i2c0: > > > > tps: tps@24 { > > reg = <0x24>; }; > > > > baseboard_eeprom: baseboard_eeprom@50 { > > compatible = "at,24c256"; > > reg = <0x50>; }; > > > > Thus if that blocks access thru /dev/i2c-0, i guess it blocks it... > > btw the "UU" from i2cdetect in 0x24/0x50 give you a hint that the > normal i2cXYZ can't access them as they are currently busy (with the > kernel).. > > root@beaglebone:~# i2cdetect -y -r 0 > 0 1 2 3 4 5 6 7 8 9 a b c d e f > 00: -- -- -- -- -- -- -- -- -- -- -- -- -- > 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- > 20: -- -- -- -- UU -- -- -- -- -- -- -- -- -- -- -- > 30: -- -- -- -- 34 -- -- -- -- -- -- -- -- -- -- -- > 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- > 50: UU -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- > 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- > 70: 70 -- -- -- -- -- -- -- > > (no idea where 0x34/0x70 are coming from at the moment..) > > Regards, > > -- > Robert Nelson > http://www.rcn-ee.com/ > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/groups/opt_out. > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
