Re: [PATCH] base: Change power/wakeup output from "" to "unsupported" if wakeup feature isn't supported by a device

On Monday, 7 of January 2008, Yi Yang wrote:

On Fri, 2008-01-04 at 08:09 -0800, David Brownell wrote:

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This patch changes empty output to "unsupported" in order that a user knows
wakeup feature isn't supported by this device when he/she
'cat /sys/devices/.../power/wakeup', please consider to apply,
thanks.

What about simply removing "wakuep" file if wakeup is not supported?

It may not *stay* unsupported, so I think changing it in either
of those permanent ways would be confusing/misleading.

For example, USB devices have multiple states ... minimally, an
unconfigured state, and a configured state.  Some have multiple
configurations.  Only configured states can be wakeup-capable.
So a given device might have three states, but support wakeup
except in one of them...

If so, we can change "unsupported" to "unconfigurable" or "inoperable"
which can cover the states "unconfigured", "unsupported" and other
unknown states. :-).

The main problem with your patch is that is changes a documented behavior
visible by the user space.  That should be done very cautiously.

Thanks,
Rafael