On Wed, 4 Jan 2023 14:39:51 -0500
Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
> On Wed, Jan 04, 2023 at 06:27:50PM +0100, Petr Tesařík wrote:
> > On Wed, 4 Jan 2023 12:04:22 -0500
> > Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
> > > At this point the host sends a Get-Device-Status request to the device
> > > (not shown in the log).
> > >
> > > [...]
> > >
> > > The fact that the host is retrying means that the status request got an
> > > error. Unfortunately the log message doesn't say sort of error
> > > occurred.
> >
> > OK, I see. The URB indicates success, but there is no data:
> >
> > 45 0.432232 host 1.50.0 USB 64 GET STATUS Request
> > 46 0.432659 1.50.0 host USB 64 GET STATUS Response
> >
> > Frame 46: 64 bytes on wire (512 bits), 64 bytes captured (512 bits) on interface usbmon1, id 0
> > USB URB
> > [Source: 1.50.0]
> > [Destination: host]
> > URB id: 0xffff98b4383c8d80
> > URB type: URB_COMPLETE ('C')
> > URB transfer type: URB_CONTROL (0x02)
> > Endpoint: 0x80, Direction: IN
> > Device: 50
> > URB bus id: 1
> > Device setup request: not relevant ('-')
> > Data: present ('\0')
> > URB sec: 1672851450
> > URB usec: 569060
> > URB status: Success (0)
> > URB length [bytes]: 0
> > Data length [bytes]: 0
> > -------------------------^
> > This should be 2, and the device should send a 16-bit status word. Hm.
> >
> > [Request in: 45]
> > [Time from request: 0.000427000 seconds]
> > Unused Setup Header
> > Interval: 0
> > Start frame: 0
> > Copy of Transfer Flags: 0x00000200, Dir IN
> > Number of ISO descriptors: 0
> >
> > While I do agree that the Samsung phone download mode USB stack
> > implementation is crappy, multiple models and many users are affected. I
> > wonder what would be a sensible workaround in heimdall and/or libusb...
> >
> > Setting a global module parameter does not sound great.
>
> Another option would be to create a short udev script that would write
> "on" to the power/control attribute file (thereby turning autosuspend
> off) whenever it sees a new USB device with the vendor and product IDs
> of your phone. That seems like a very practical solution.
Yes, that sounds good, because autosuspend is usually not set to zero.
Thank you! FWIW it works for me, and I have also proposed this solution
in the heimdall GitHub issue. They install their own udev rules file
already, so the patch is a one-liner.
BTW manufacturing broken USB devices in large quantities should become
a crime and a federal felony... ;-)
Petr T
