Re: kern/54070: urtwn(4) does not work on OHCI

[Andreas Gustafsson <gson%gson.org@localhost>]

The following reply was made to PR kern/54070; it has been noted by GNATS.

From: Andreas Gustafsson <gson%gson.org@localhost>
To: Nick Hudson <nick.hudson%gmx.co.uk@localhost>
Cc: gnats-bugs%netbsd.org@localhost
Subject: Re: kern/54070: urtwn(4) does not work on OHCI
Date: Wed, 27 Nov 2019 22:53:30 +0200

 Nick Hudson wrote:
 >  Ok, I see that you're trying to implement the recommendation in the PDF.
 
 That's not quite how I would put it; I actually devised the patch
 before I found the PDF.  I am just trying to address the specific bug
 that is preventing urtwn from working on ohci.
 
 >  I think it's best to remove OHCI_TD_R completely for bulk/interrupt
 >  transfers.
 >  
 >    http://src.illumos.org/source/xref/netbsd-src/sys/dev/usb/ohci.c#666
 
 Line of the beast :) That line is setting OHCI_TD_R on the last TD
 only, which is probably safe since there is no next TD to continue to,
 but leaving it cleared should also work, and I have no opinion on
 which option is better.  Leaving it cleared should make the need for
 my patch more obvious as the bug would then also hit drivers that
 request transfers of 8k or less, not just those that request more
 than 8k so that multiple TDs are required.
 
 >  I haven't thought about control transfers though.
 
 Neither have I.
 -- 
 Andreas Gustafsson, gson%gson.org@localhost