Re: [PATCH v4 1/2] hw: canokey: Remove HS support as not compliant to the spec

[Hongren Zheng]

On Sat, Jun 25, 2022 at 10:21:37PM +0800, MkfsSion wrote:
> Canokey core currently using 16 bytes as maximum packet size for
> control endpoint, but to run the device in high-speed a 64 bytes
> maximum packet size is required according to USB 2.0 specification.
> Since we don't acutally need to run the device in high-speed, simply
> don't assign high member in USBDesc.
> 
> When canokey-qemu is used with xhci, xhci would drive canokey
> in high speed mode, since the bcdUSB in canokey-core is 2.1,
> yet canokey-core set bMaxPacketSize0 to be 16, this is out
> of the spec as the spec said that ``The allowable maximum
> control transfer data payload sizes...for high-speed devices,
> it is 64 bytes''.
> 
> In this case, usb device validation in Windows 10 LTSC 2021
> as the guest would fail. It would complain
> USB\DEVICE_DESCRIPTOR_VALIDATION_FAILURE.
> 
> Note that bcdUSB only identifies the spec version the device
> complies, but it has no indication of its speed. So it is
> allowed for the device to run in FS but comply the 2.1 spec.
> 
> To solve the issue we decided to just drop the high
> speed support. This only affects usb-ehci as usb-ehci would
> complain speed mismatch when FS device is attached to a HS port.
> That's why the .high member was initialized in the first place.
> Meanwhile, xhci is not affected as it works well with FS device.
> Since everyone is now using xhci, it does no harm to most users.
> 
> Suggested-by: Hongren (Zenithal) Zheng <i@zenithal.me>
> Signed-off-by: YuanYang Meng <mkfssion@mkfssion.com>
> ---
>  hw/usb/canokey.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/hw/usb/canokey.c b/hw/usb/canokey.c
> index 4a08b1cbd7..6a7ab965a5 100644
> --- a/hw/usb/canokey.c
> +++ b/hw/usb/canokey.c
> @@ -56,7 +56,6 @@ static const USBDesc desc_canokey = {
>          .iSerialNumber     = STR_SERIALNUMBER,
>      },
>      .full = &desc_device_canokey,
> -    .high = &desc_device_canokey,
>      .str  = desc_strings,
>  };
>  
> -- 
> 2.36.1
>

Reviewed-by: Hongren (Zenithal) Zheng <i@zenithal.me>

kraxel could you please pick this patch and queue
this up for PULL, thanks!