From: Armin <akuster@pacbell•net>
To: David Gibson <david@gibson•dropbear.id.au>
Cc: linuxppc-embedded@lists•linuxppc.org
Subject: Re: Workaround for USB DMA bugs
Date: Wed, 03 Apr 2002 08:17:52 +0000 [thread overview]
Message-ID: <3CAABAB0.5030000@pacbell.net> (raw)
In-Reply-To: 20020403024321.GN1026@zax
David Gibson wrote:
> Well, I'm not sure I'd want to pollute the tree with this sort of
> hack, but on the other hand it makes things work that wouldn't
> otherwise.
>
> Does anyone think it's a good idea to commit the following patch:
>
> diff -urN /home/dgibson/kernel/linuxppc_2_4_devel/arch/ppc/mm/cachemap.c linux-grinch/arch/ppc/mm/cachemap.c
> --- /home/dgibson/kernel/linuxppc_2_4_devel/arch/ppc/mm/cachemap.c Thu Mar 14 13:49:01 2002
> +++ linux-grinch/arch/ppc/mm/cachemap.c Wed Apr 3 11:51:30 2002
> @@ -137,7 +137,18 @@
> case PCI_DMA_NONE:
> BUG();
> case PCI_DMA_FROMDEVICE: /* invalidate only */
> +#ifdef CONFIG_USB
> + /* The USB stack is broken in that it uses DMA buffers
> + on the stack which are on the stack and not
> + cacheline aligned. That means cache invalidates
> + before DMA transfers corrupt the stack on machines
> + without DMA-consistent cache. This is a nasty
> + workaround until the USB layer is fixed (apparently
> + done in 2.5). */
> + flush_dcache_range(start, end);
> +#else
> invalidate_dcache_range(start, end);
> +#endif
> break;
> case PCI_DMA_TODEVICE: /* writeback only */
> clean_dcache_range(start, end);
>
>
> --
> David Gibson | For every complex problem there is a
> david@gibson•dropbear.id.au | solution which is simple, neat and
> | wrong. -- H.L. Mencken
> http://www.ozlabs.org/people/dgibson
>
>
>
>
>
Ah yes, We have done something simular (internally) and had the same
reservations. This will help me with the ocp usb drivers i am working
on. I would like to see some way of reminding us that this was done.
let say a config option for 4xx_usb_dma_workarround.
.
-armin
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
next prev parent reply other threads:[~2002-04-03 8:17 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-04-03 2:43 Workaround for USB DMA bugs David Gibson
2002-04-03 8:17 ` Armin [this message]
2002-04-03 17:39 ` Frank Rowand
2002-04-03 17:49 ` Dan Malek
2002-04-03 20:43 ` David Blythe
2002-04-03 23:34 ` David Gibson
2002-04-03 9:45 ` "David Müller (ELSOFT AG)"
2002-04-03 23:35 ` David Gibson
2002-04-03 17:42 ` Dan Malek
2002-04-03 23:40 ` David Gibson
2002-04-04 2:54 ` Dan Malek
2002-04-04 3:48 ` David Gibson
2002-04-04 4:09 ` Dan Malek
2002-04-04 5:23 ` David Gibson
2002-04-04 6:08 ` Dan Malek
2002-04-04 6:30 ` David Gibson
2002-04-04 20:21 ` David Blythe
2002-04-04 12:35 ` Brad Parker
2002-04-04 14:12 ` Dan Malek
-- strict thread matches above, loose matches on Subject: below --
2002-04-04 4:19 Jeremy Rosen
2002-04-04 6:16 ` Dan Malek
2002-04-04 6:32 ` David Gibson
2002-04-04 6:40 Rosen Jeremy
2002-04-04 6:52 ` David Gibson
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=3CAABAB0.5030000@pacbell.net \
--to=akuster@pacbell$(echo .)net \
--cc=david@gibson$(echo .)dropbear.id.au \
--cc=linuxppc-embedded@lists$(echo .)linuxppc.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox