Re: [PATCH 1/2] hid2hci: iterate libusb devices twice

[Mario Limonciello <mario_limonciello@dell.com>]

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Hi Kay:

Kay Sievers wrote:
> On Mon, Jul 27, 2009 at 23:32, Marcel Holtmann<marcel@holtmann.org> wrote:
>   
>
> Now it's getting funny. We need to call the nonsense two times to make
> it work? We need to fix the real issue here instead of doing guesswork
> and adding hacks like this. Any idea what's going on with the first
> scan? The device node is guaranteed to exist when we call stuff from
> RUN+= instructions.
>
>   
I'm not sure what's going on here, but I think i'll just go down that
road of pulling the necessary code out of libusb's find_devices to just
craft a usb_device object with the information we already have so there
is no necessary scanning in the first place.  There will still  be a
dependency on libusb to be able to send a usb_control_msg, claim, etc,
but at least the time consuming, unnecessary scan will be gone.
>
> Well, libusb might be ok for stuff that just searches things which are
> always there, it's definitely not suitable to be used in conjunction
> with udev. The entire coldplug with 500 devices takes ~0.5 seconds
> here, while a single call to libusb takes ~0.15 just to find the
> device we already have. That alone is not acceptable, and now we
> should call the useless scan twice? Tsss ... :)
>   
Yeah I understand.  I'll follow up after I get something else together.

-- 
Mario Limonciello
*Dell | Linux Engineering*
mario_limonciello@dell.com


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