* [Qemu-devel] About usb passthru and speed mismatch
@ 2015-06-11 15:47 Lin Ma
2015-06-16 13:21 ` Gerd Hoffmann
0 siblings, 1 reply; 2+ messages in thread
From: Lin Ma @ 2015-06-11 15:47 UTC (permalink / raw)
To: kraxel; +Cc: qemu-devel
Hi Gerd,
Based on the current implementation of 'usb_host_open' in
hw/usb/host-libusb.c,
When user performs usb_add, The usb device will be detached from kernel
first, Then be checked for speed mismatch second.
If it found speed mismatch, The usb device isn't attached to guest, But
the usb device can't be reattached to kernel either.
I'd like to write patch to add 'usb_check_attach' before detaching the
device from kernel _or_ add 'usb_host_attach_kernel' under 'fail:' of
usb_host_open, (the latter doesn't make sense I think).
May I have your thoughts?
BTW, Have you missed a patch: "usb: Use usb_bus_find(-1) instead of
usb_enabled() in usb_device_add/usb_device_del" which sending on June
4th ? May I have your thoughts about that patch as well?
Thanks,
Lin
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [Qemu-devel] About usb passthru and speed mismatch
2015-06-11 15:47 [Qemu-devel] About usb passthru and speed mismatch Lin Ma
@ 2015-06-16 13:21 ` Gerd Hoffmann
0 siblings, 0 replies; 2+ messages in thread
From: Gerd Hoffmann @ 2015-06-16 13:21 UTC (permalink / raw)
To: lma; +Cc: qemu-devel
On Do, 2015-06-11 at 23:47 +0800, Lin Ma wrote:
> Hi Gerd,
>
> Based on the current implementation of 'usb_host_open' in
> hw/usb/host-libusb.c,
>
> When user performs usb_add, The usb device will be detached from kernel
> first, Then be checked for speed mismatch second.
> If it found speed mismatch, The usb device isn't attached to guest, But
> the usb device can't be reattached to kernel either.
>
> I'd like to write patch to add 'usb_check_attach' before detaching the
> device from kernel _or_ add 'usb_host_attach_kernel' under 'fail:' of
> usb_host_open, (the latter doesn't make sense I think).
Re-attach to the kernel when open fails (for whatever reasons) makes
perfect sense to me.
cheers,
Gerd
^ permalink raw reply [flat|nested] 2+ messages in thread
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2015-06-11 15:47 [Qemu-devel] About usb passthru and speed mismatch Lin Ma
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