Re: [Qemu-devel] [PATCH 14/14] usb-host: add timeout handler

[Johannes Stezenbach]

Hi,

On Tue, Apr 24, 2012 at 05:51:31PM +0200, Gerd Hoffmann wrote:
> Add a timeout handler.  In case bulk transfers take too long to finish
> the request will be canceled.  The timeout is tunable via property, by
> default it is 5 seconds.

This patch causes an issue for my firmware download.  The
protocol used is very simple and uses a single bulk out endpoint:
- send start packet
- send firmware image
- send end packet

When the "end" packet is received the actual flashing starts,
which can take minutes.  The device will not ACK the packet
until flashing completes.  Thus I now get an error from the
flash tool (while flashing completes on the device).
Qemu says:

  husb: urb timeout (5 secs, #1)

I think 5 seconds default timeout may also cause issues
with slow devices (hard disk spinning up, CDROM reading
disc TOC etc.).  It seems unneccessary since the guest OS
handles timeouts specified by drivers/applications
on URB submission, and will cancel transfers on timeout.
Has this been added to fix an actual problem?


Thanks,
Johannes