Mike Isely wrote:
On Sun, 7 Jun 2009, Roger wrote:
>From looking at "linux/drivers/media/dvb/frontends/s5h1411.c", The
s5h1411_readreg wants to see "2" but is getting "-5" from the i2c bus.
--- Snip ---
s5h1411_readreg: readreg error (ret == -5)
pvrusb2: unregistering DVB devices
device: 'dvb0.net0': device_unregister
--- Snip ---
What exactly does this mean?
Roger:
It means that the module attempted an I2C transfer and the transfer
failed. The I2C adapter within the pvrusb2 driver will return either
the number of bytes that it transferred or a failure code. The failure
code, as is normal convention in the kernel, will be a negated errno
value. Thus the expected value of 2 would be the fact that it probably
tried a 2 byte transfer, while the actual value returned of -5 indicate
an EIO error, which is what the pvrusb2 driver will return when the
underlying I2C transaction has failed.
Of course the real question is not that it failed but why it failed.
And for that I unfortunately do not have an answer. It's possible that
the s5h1411 driver did something that the chip didn't like and the chip
responded by going deaf on the I2C bus. More than a few I2C-driven
parts can behave this way. It's also possible that the part might have
been busy and unable to respond - but usually in that case the driver
for such a part will be written with this in mind and will know how /
when to communicate with the hardware.
Roger:
Another possibility, although I don't know the PVRUSB2 driver too well, the
s5h1411 is being held in reset when the driver unloads _AFTER_ the last active
use was analog video (assuming the s5h1411 is floated in reset as the FX2 input
port might be shared with the analog encoder)
I don't have all the details so your failure case could be complete different.
--
Steven Toth - Kernel Labs
http://www.kernellabs.com
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