cvs commit: src/sys/dev/usb ehci.c ohci.c

[Marius Strobl]

On Wed, Apr 23, 2008 at 01:43:55PM -0700, Sam Leffler wrote:
> Marius Strobl wrote:
> >On Sat, Apr 12, 2008 at 09:33:58PM +0200, Marius Strobl wrote:
> >  
> >>On Thu, Mar 20, 2008 at 04:19:26PM +0000, Sam Leffler wrote:
> >>    
> >>>sam         2008-03-20 16:19:25 UTC
> >>>
> >>>  FreeBSD src repository
> >>>
> >>>  Modified files:
> >>>    sys/dev/usb          ehci.c ohci.c 
> >>>  Log:
> >>>  Workaround design botch in usb: blindly mixing bus_dma with PIO does 
> >>>  not
> >>>  work on architectures with a write-back cache as the PIO writes end up
> >>>  in the cache which the sync(BUS_DMASYNC_POSTREAD) in 
> >>>  usb_transfer_complete
> >>>  then discards; compensate in the xfer methods that do PIO by pushing 
> >>>  the
> >>>  writes out of the cache before usb_transfer_complete is called.
> >>>  
> >>>  This fixes USB on xscale and likely other places.
> >>>  
> >>>  Sponsored by:   hobnob
> >>>  Reviewed by:    cognet, imp
> >>>  MFC after:      1 month
> >>>  
> >>>  Revision  Changes    Path
> >>>  1.62      +16 -0     src/sys/dev/usb/ehci.c
> >>>  1.171     +16 -0     src/sys/dev/usb/ohci.c
> >>>      
> >>This causes a crash during boot on sparc64. Looks like map is still
> >>NULL at that point.
> >>
> >>    
> >
> >Are you ok with the change below or would that also prevent
> >your kludge from taking effect?
> >
> >Marius
> >
> >Index: ehci.c
> >===================================================================
> >RCS file: /usr/data/bsd/cvs/fbsd/src/sys/dev/usb/ehci.c,v
> >retrieving revision 1.62
> >diff -u -r1.62 ehci.c
> >--- ehci.c	20 Mar 2008 16:19:25 -0000	1.62
> >+++ ehci.c	23 Apr 2008 20:23:58 -0000
> >@@ -664,6 +664,8 @@
> > 	usbd_pipe_handle pipe = xfer->pipe;
> > 	bus_dma_tag_t tag = pipe->device->bus->buffer_dmatag;
> > 	struct usb_dma_mapping *dmap = &xfer->dmamap;
> >+	if (dmap->map == NULL)
> >+		return;
> > 	bus_dmamap_sync(tag, dmap->map, BUS_DMASYNC_PREWRITE);
> > }
> > 
> >Index: ohci.c
> >===================================================================
> >RCS file: /usr/data/bsd/cvs/fbsd/src/sys/dev/usb/ohci.c,v
> >retrieving revision 1.171
> >diff -u -r1.171 ohci.c
> >--- ohci.c	20 Mar 2008 16:19:25 -0000	1.171
> >+++ ohci.c	21 Apr 2008 19:13:54 -0000
> >@@ -1571,6 +1571,8 @@
> > 	usbd_pipe_handle pipe = xfer->pipe;
> > 	bus_dma_tag_t tag = pipe->device->bus->buffer_dmatag;
> > 	struct usb_dma_mapping *dmap = &xfer->dmamap;
> >+	if (dmap->map == NULL)
> >+		return;
> > 	bus_dmamap_sync(tag, dmap->map, BUS_DMASYNC_PREWRITE);
> > }
> > 
> >
> >
> >  
> You have not identified why you don't have a dma map.  I don't have a 
> way to diagnose your problem and so far as I know no other platform had 
> an issue w/ the change.  I suggest you figure out why your map is not 
> setup instead of adding a hack.
> 

It's because the usb(4) code doesn't create DMA maps for
zero-length transfers, see usbd_transfer(). In the case of
the backtrace I posted not for usbd_set_address(), which
does USETW(req.wLength, 0) so later on size is 0 in
usbd_transfer() hence no DMA map. I don't know why your
hack doesn't also crash other platforms.

Marius