[PATCH] usb: Add 1ms delay after first Get Descriptor request

[Janne Grunau]

On 2022-10-31 21:57:39 +0100, Marek Vasut wrote:
> On 10/31/22 20:27, Simon Glass wrote:
> > Hi Marek,
> 
> Hi,
> 
> > On Sun, 30 Oct 2022 at 16:38, Marek Vasut <marex at denx.de> wrote:
> > > 
> > > Logitech Unifying Receiver 046d:c52b bcdDevice 12.10 seems
> > > sensitive about the first Get Descriptor request. If there
> > > are any other requests in the same microframe, the device
> > > reports bogus data, first of the descriptor parts is not
> > > sent to the host. Wait over one microframe duration before
> > > issuing subsequent requests to avoid probe failure with
> > > this device, since it can be used to connect USB keyboards.
> > > 
> > > Signed-off-by: Marek Vasut <marex at denx.de>
> > > ---
> > > Cc: Janne Grunau <j at jannau.net>
> > > Cc: Mark Kettenis <kettenis at openbsd.org>
> > > ---
> > >   common/usb.c | 11 +++++++++++
> > >   1 file changed, 11 insertions(+)
> > 
> > Is this device complying with the spec or is it broken?

This is not just this device. We have seen this reported with a few 
keyboards on apple silicon devices. Keychron devices are one group I can 
remember.

> > 
> > In any case we need a way to enable/disable this as it will slow down
> > unaffected platforms.
> 
> This makes little difference, since anyone can plug such device into a port
> and suddenly the platform is affected. We cannot really predict what users
> have on their desks.

Would it make sense to limit it to dwc3 host controllers or do you fear 
the same problem could happen with other controllers on fast boards?

In any case patch fixes the problem here as well.

Tested-by: Janne Grunau <j at jannau.net>

Thanks,

Janne