Re: [PATCH] USB: output an error message when the pipe type doesn'tmatch the endpoint type

[Xiaofan Chen]

On Tue, Aug 31, 2010 at 9:52 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
> On Tue, 31 Aug 2010, Clemens Ladisch wrote:
>
>> Simon Arlott wrote:
>> > Commit f661c6f8c67bd55e93348f160d590ff9edf08904 adds a check of the pipe type if
>> > CONFIG_USB_DEBUG is enabled,
>>
>> I didn't see that commit last year, but wouldn't it break devices like
>> the ESI MIDI Mate whose descriptors want to have low-speed bulk transfers
>> and where the driver has to submit interrupt transfers instead to get it
>> to work at all?
>
> When the kernel sees those invalid low-speed bulk endpoint descriptors,
> it changes its internal copy of the descriptor to interrupt.  Hence
> when the driver submits interrupt URBs, they work correctly.
>

Interesting.

FYI: even though XP/Win2k allow low-speed bulk endpoints, Vista
and Win7 do not allow that.

There are hacks to get around that.
http://www.recursion.jp/avrcdc/lowbulk.html

I took a look at the libusb-win32 source and indeed the author
is using the same trick of submit interrupt URBs.


-- 
Xiaofan
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