Re: [PATCH] dell-wmi Switch support and Tablet switch definition

[Rafi Rubin <rafi@seas.upenn.edu>]

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Matthew Garrett wrote:
> On Fri, Jun 19, 2009 at 03:28:48PM -0400, Rafi Rubin wrote:
> 
>> I agree polling the tablet state would be a good thing.  But that does not mean we should not
>> support the signals until we are ready to support polling.
>>
>> If you are suggesting that we should not use an EV_SW because we will eventually poll the hardware
>> instead of keeping the state in software, then I have no problem with sending keys or other events.
> 
> No, my point is that there's little benefit in providing EV_SW if the 
> initial value is going to be wrong. Software simply can't depend on it. 
> The code's absolutely fine, but there's a risk that it'll break 
> otherwise working desktops until we know how to set the initial value.


The signal is not a toggle.  Its an explicit "going to tablet" and "coming from tablet".  And the
initial value is "non-tablet" mode, which is what must be assumed without this support.

So the only new case where a wrong assumption may be made is if the screen is flipped out of tablet
mode during suspend or hibernate.  But we _don't_ have the potential of a toggle being inverted and
it rotating the screen to something silly every time you flip it.

I think the benefits of the partial support far outweight the potential hazards.


That being said, if you have any clue how to probe the state, I would be very happy to help you.
And I'd agree that signals can wait.


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