Date: Wed, 23 Apr 2008 15:05:56 -0600 From: Scott Long <scottl@samsco.org> To: Marius Strobl <marius@alchemy.franken.de> Cc: cvs-src@FreeBSD.org, Sam Leffler <sam@FreeBSD.org>, cvs-all@FreeBSD.org, src-committers@FreeBSD.org Subject: Re: cvs commit: src/sys/dev/usb ehci.c ohci.c Message-ID: <480FA4B4.50006@samsco.org> In-Reply-To: <20080423205943.GG99566@alchemy.franken.de> References: <200803201619.m2KGJQr7033985@repoman.freebsd.org> <20080412193358.GA44768@alchemy.franken.de> <20080423203622.GA66545@alchemy.franken.de> <480F9F8B.5050209@freebsd.org> <20080423205943.GG99566@alchemy.franken.de>
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Marius Strobl wrote: > 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. > > If there's a transfer without a DMA operation, then why is the DMA API being used? Scott
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