Re: Chapter 9 tool for linux

On Mon, 2 Aug 2010, Felipe Balbi wrote:

> Hi all,
> =

> I've been willing to write a chapter 9 tool for linux. The specification =
for it
> can be found when you install usbcv from usb-if on a windows machine.
> =

> It's currently rather complicated to implement it with libusb because
> we have a few missing "test features" on usbfs side and some features
> that cause problems on libusb.
> =

> First of all it's impossible to set an address to a device via libusb. We=
ll
> I cooked the control message by hand, but then when I try to talk to devi=
ce
> the address is not updated to the libusb_device_handle * so every other
> transfer to that device will fail if we set a different address.
> =

> Another one is that libusb caches the descriptors, so subsequent
> get descriptor requests will just return the cached version, but USBCV
> that's a no-no since we need to exercise a real GetDescriptor() request.
> I understand why libusb does that (to avoid waking up a sleeping device),
> but would there be a way to overcome that ?
> =

> The most critical part of the USBCV Spec that needs to be well supported
> is the device states you have to handle and run the tests, I'm quoting
> the spec below:
> =

> 3. Test Descriptions
> 3.1       Chapter 9 (Device) Tests
>     The Chapter 9 tests cover the device support of the commands set
> for the in Chapter 9 of the USB
>     specification. There are three different device states. Many of
> the tests are run with the device under
>     test in more than one of these states. Each of the states and
> procedure used to put the device into this
>     state are described here. This information is provided to help
> with debugging in cases where the
>     device under test is not even reaching the desired starting state
> for the test The individual tests
>     mention which device states they are run on =E2=80=93 but don=E2=80=
=99t repeat the
> setup procedure. The device states
>     are as follows:
>     Default State:
>     1.    Put the device in the configured state following the procedure =
below.
>     2.    Issue a valid Set Configuration command to the device with
> configuration value zero.
>     3.    Issue a valid Get Configuration command and verify that the
> device responds with zero.
>     4.    Issue a valid Set Address command to the device with address ze=
ro.
>     Address State:
>     1.    Put the device in the configured state following the procedure =
below.
>     2.    Issue a valid Set Configuration command to the device with
> configuration value zero.
>     3.    Issue a valid Get Configuration command to the device and
> verify that device responds with zero.
>     Configured State: The device is enumerated using the following proced=
ure.
>     1.    Reset the USB host controller.
>     2.    For each port on the USB host controller turn on port power.
>     3.    Sleep for 1 Second.
>     4.    Drive port reset on each host port. Sleep for 50
> milliseconds. Clear port reset.
>     5.    Check host port enable.
>     6.    If host port is enabled enumerate the device on the port.
>     7.    Issue a valid set configuration command for the
> configuration to be tested.
>     8.    Issue a valid get configuration command and verify that the
> correct configuration is returned.
>      Enumerate Device Routine:
>          Get device descriptor using a maximum packet size of 64.
> (This will cause a short packet for
>      1.
>          devices with maxpacketsize0 < 64)
>      2.  Issue a Set Address command with the next available USB address.
>      3.  Get the device descriptor again with the right maximum packet si=
ze.
>      4.  Get configuration descriptor asking for a number of bytes
> equal to configuration descriptor size
>          only.
>      5.  Issue a Set Configuration command for the first configuration
> supported by the device.
>      6.  Get the configuration descriptor again asking for a number of
> bytes equal to the configuration
>          descriptor size.
>      7.  Get the configuration descriptor using the total length of
> the entire descriptor.
> If the descriptors indicated the device is a hub continue with the steps =
below:
>      8.  Get the hub class descriptor.
>      9.  Issue a Set Port Feature command with power selector
> PORT_POWER for each port on the hub.
>      10. Sleep for 1 second.
>      11. Issue Get Port Status commands for each port.
>      12. If the connect bit is set in the port status issue a port
> reset and proceed to step 13. Otherwise stop.
>      13. Sleep for 50 milliseconds.
>      14. Check the port status to ensure the enable bit has been set.
> Then proceed to the enumerate device
>          routine.
> =

> If we support those operations, I believe a USBCV for linux could be
> written (well, it would actually
> work on Mac OSX and Windows too, I guess).
> =

> Any comments would be welcome.

I don't know about other operating systems, but Linux does not permit =

user programs to do many of these things -- especially changing device =

addresses.  So it doesn't matter what you put into libusb, this won't =

work.

Alan Stern


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