From: Clemens Ladisch <clemens@ladisch.de>
To: shal@free.fr
Cc: alsa-devel@alsa-project.org
Subject: Re: Some information about UsbPre2 UAC2 support
Date: Sat, 26 Jan 2013 21:29:10 +0100 [thread overview]
Message-ID: <51043C96.40508@ladisch.de> (raw)
In-Reply-To: <199306935.463022264.1359222606997.JavaMail.root@spooler2-g27.priv.proxad.net>
shal@free.fr wrote:
> For some compatibility raison, Sound device developer want only send a UAC1 configuration when the Operating system is Windows.
> The used method is based on the length of the setup packet during the device get_descriptor function.
> If the length is 64, the OS is considered as Windows.
> Linux have choosen also this value.
Because there are buggy devices that haven been tested only with Windows
and will blow up if other values are chosen.
I guess somebody has to add a quirk for this device to the driver.
> Now, the USB device descriptor has two configuration descriptors :the first is a UAC1 and the second is a UAC2.
>
> As UAC1 is a valid configuration descriptor, the usb stack choose this configuration.
>
> I have patched the usb_choose_configuration() function in file driver/usb/core/generic.c for overwrite the value with the good one.
This can be changed later in the driver with usb_driver_set_configuration().
Regards,
Clemens
next prev parent reply other threads:[~2013-01-26 20:30 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1897855798.462977802.1359220888088.JavaMail.root@spooler2-g27.priv.proxad.net>
2013-01-26 17:50 ` Some information about UsbPre2 UAC2 support shal
2013-01-26 20:29 ` Clemens Ladisch [this message]
2013-01-28 12:43 ` shal
2013-01-28 13:10 ` Clemens Ladisch
2013-01-28 13:48 ` shal
2013-01-28 14:17 ` Clemens Ladisch
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