Re: [linux-usb-devel] detecting when keys are being pressed on a keyboard

On 9/24/07, Oliver Neukum [off-list ref] wrote:

Am Montag 24 September 2007 schrieb Dmitry Torokhov:

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Hi Oliver,

On 9/24/07, Oliver Neukum [off-list ref] wrote:

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Am Freitag 21 September 2007 schrieb Jiri Kosina:

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Hi Oliver,

HID doesn't keep any permanent state by itself. If you want to know
whether a given key is currently pressed or not, you'd have to inspect the
bitfields inside input_dev*, I am afraid.

I see no way to do this without a race condition. The field isn't locked
as far as I can tell.

You can take input_dev->event_lock to stop event from propagating
through input core while you are evaluating the bits. Input lcoking
changes are im -mm and will be merged into 2.6.24.

Hi Dmitry,

I was thinking about a second approach. As all keypresses run through
the interrupt handlers of the hid driver, how about checking the bit field
in the interrupt handler after calling hid_input_report() ?

That should work as well I think.

-- 
Dmitry