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From: Bandan Das <bsd@redhat.com>
To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Isaac Lozano <109lozanoi@gmail.com>,
	qemu-devel@nongnu.org, kraxel@redhat.com
Subject: Re: [Qemu-devel] [PATCH] usb-mtp: fix usb_mtp_get_device_info so that libmtp on the guest doesn't complain
Date: Tue, 26 Apr 2016 17:28:37 -0400	[thread overview]
Message-ID: <jpgshy8giuy.fsf@linux.bootlegged.copy> (raw)
In-Reply-To: <20160426091156.GA10650@stefanha-x1.localdomain> (Stefan Hajnoczi's message of "Tue, 26 Apr 2016 10:11:56 +0100")

Stefan Hajnoczi <stefanha@gmail.com> writes:

> On Sun, Apr 17, 2016 at 04:29:53AM -0700, Isaac Lozano wrote:
>> If an application uses libmtp on the guest system,
>> it will complain with the warning message:
>> LIBMTP WARNING: VendorExtensionID: ffffffff
>> LIBMTP WARNING: VendorExtensionDesc: (null)
>> LIBMTP WARNING: this typically means the device is PTP (i.e. a camera) but
>> not a MTP device at all. Trying to continue anyway.
>> 
>> This is because libmtp expects a MTP Vendor Extension ID of 0x00000006 and a
>> MTP Version of 0x0064. These numbers are taken from Microsoft's MTP Vendor
>> Extension Identification Message page and are what most physical devices
>> show.
>> 
>> Signed-off-by: Isaac Lozano <109lozanoi@gmail.com>
>> ---
>>  hw/usb/dev-mtp.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> Welcome to QEMU!
>
> Link to MTP Vendor Extension Identification Message page for other
> reviewers:
> https://msdn.microsoft.com/en-us/library/ff632482.aspx

I am confused why the MTP spec on usb.org specifies in 5.1.1.2 that
this value should be 0xffffffff for MTP devices. Is it just not updated
or there are similar MS specific differences to watch out for ? Either
way, it seems libmtp will always be a good reference when we are stuck
with such discrepencies.

> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

  reply	other threads:[~2016-04-26 21:28 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-17 11:29 [Qemu-devel] [PATCH] usb-mtp: fix usb_mtp_get_device_info so that libmtp on the guest doesn't complain Isaac Lozano
2016-04-26  9:11 ` Stefan Hajnoczi
2016-04-26 21:28   ` Bandan Das [this message]
2016-05-11  8:34 ` Gerd Hoffmann

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