Am 23.11.2012 18:20, schrieb Antti Palosaari: > On 11/23/2012 07:01 PM, Frank Schäfer wrote: >> Hi, >> >> I've got a Hauppauge HVR-900 (65008/A1C0) today. First, the device >> showed up as USB device 7640:edc1 (even after several unplug - replug >> cycles), so I decided to add this VID:PID to the em28xx driver to see >> what happens. >> That worked fine, em2882/em2883, tuner xc2028/3028 etc. were detected >> properly. >> Later I noticed, that the device now shows up as 2040:6500, which is the >> expected ID for this device. >> Since then, the device maintains this ID. I also checked if Windows is >> involved, but it shows up with the same ID there. >> >> Does anyone have an idea what could have happened ??? >> I wonder if we should add this ID to the em28xx driver... > > em28xx chip reads USB ID from the external eeprom using I2C just after > it was powered. After USB ID is got it connects to the USB bus using > that ID. If there is no external eeprom it uses chipset default USB > ID, which is 0xeb1a as vendor ID and some other number defined for > chip model as device ID. In that case those wrong IDs seems to be > total garbage, which indicates there is some hardware problems when > communicating towards eeprom. > Yeah, hardware problems, sure... but I wonder why the USB ID was/is persistent ? Communication problems caused by circuit defect should lead to a rather random behavior... On power loss, the everything except (ee)prom(s) contents should be reset to a default state. And if the eeprom was corrupted, how could it magically recover ? Also: the USB id is read from the eeprom even without a OS driver beeing involved, but the first usage of the driver seems to have "fixed" the ID... Regards, Frank > That method is not only Empia USB interface chips but almost all > chipset uses just similar method. > > > regard > Antti > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
