[RESEND, PATCHv6 1/1] Add support for GMT G762/G763 PWM fan controllers

Hi Simon,

Simon Guinot [off-list ref] writes:

I have tested this patch on my 2Big Network v2 board.

Sometimes I get a weird "No such device" error while reading or writing
the hwmon sysfs attributes. For example:

# cat pwm1
cat: read error: No such device
# cat pwm1
0

Weird, I cannot reproduce that at all on my ReadyNAS Duo v2.

Note, that if the same command is executed again (just after the faulty
one), then it will succeed most of the time. The errors seems to happen
quite randomly and not very often. I'd say one time over ten tries.
I suppose this error is now visible due to the enhanced error path in
g762_update_client. It looks like we learn something by checking the
return value for i2c_smbus_read_byte_data :)

Except that, all is working as expected. This new version fixes
effectively open-loop driving when the set_cnt register is set to 0xff.

Also I am planning (hopefully this Wednesday) to test your patch on my
5Big Network v2 board. This last also embed a g762 controller but with a
three wires fan instead. Then, I should be able to test the closed-loop
mode behaviour.

Thanks for your tests, Simon.

Cheers,

a+