Re: Patch to fix/shorten "wi" freezes

In message: <[email protected]>
            Ian Dowse <[email protected]> writes:
: In message <[email protected]>, "M. Warner Losh" writes:
: >
: >For the removal, it would be better to use the bus_child_present() api
: >for the eject case.
: 
: Does the pccard system implement bus_child_present()? I just did a
: quick grep for *_child_present there without finding anything, but
: maybe I'm looking for the wrong thing. Is the idea to use something
: like
: 
: 	if (sc->wi_gone)
: 		return;
: 	<hardware operation>
: 	if (timeout) {
: 		if (!bus_child_present(sc->dev)) {
: 			sc->wi_gone = 1;
: 			return;
: 		}
: 		device_printf(sc->dev, "device timeout\n");
: 	}
: 
: so that further slow timeouts can be avoided if the device has
: really been removed? I presume it is too much overhead to just call
: bus_child_present() everywhere instead of testing `gone'.

Well, I think I have them in my tree, but haven't committed them to
the tree yet.

The reason that I'd not call it all the time is because once a device
is gone, it should stay gone until it is reattached.  At least that's
been my experience with debouncing the pccard stuff.  Also, once it is
gone, it is a lot cheaper to check a flag, than to go to hardware,
which may take several microseconds.

Warner

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