Hi,
in
https://elixir.bootlin.com/linux/latest/source/drivers/usb/core/config.c#L409
the initial value of maxp is obtained using function usb_endpoint_maxp.
maxp = usb_endpoint_maxp(&endpoint->desc);
This function
https://elixir.bootlin.com/linux/latest/source/include/uapi/linux/usb/ch9.h#L647
returns only the bits 0 - 10 of the wMaxPacketSize field, i.e. dropping
the high-bandwidth bits 11 and 12. Yet the subsequent code extracts
these bits from maxp into variable i
https://elixir.bootlin.com/linux/latest/source/drivers/usb/core/config.c#L427
, clears them in maxp, and re-sets back in one of the further checks
https://elixir.bootlin.com/linux/latest/source/drivers/usb/core/config.c#L445
IMO that means the code requires that initial value of maxp contains the
additional-transactions bits. IMO the code should be fixed with this
trivial patch (tested on my build):
===================================================================
diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c
--- a/drivers/usb/core/config.c (revision
018dd9dd80ab5f3bd988911b1f10255029ffa52d)
+++ b/drivers/usb/core/config.c (date 1638972286064)
@@ -406,7 +406,7 @@
* the USB-2 spec requires such endpoints to have wMaxPacketSize = 0
* (see the end of section 5.6.3), so don't warn about them.
*/
- maxp = usb_endpoint_maxp(&endpoint->desc);
+ maxp = endpoint->desc.wMaxPacketSize;
if (maxp == 0 && !(usb_endpoint_xfer_isoc(d) && asnum == 0)) {
dev_warn(ddev, "config %d interface %d altsetting %d endpoint 0x%X
has invalid wMaxPacketSize 0\n",
cfgno, inum, asnum, d->bEndpointAddress);
=========================
I can send a proper patch should the change be approved.
Thanks a lot,
Pavel.
