From: Sean MacLennan <smaclennan@pikatech•com>
To: Benjamin Herrenschmidt <benh@kernel•crashing.org>
Cc: linuxppc-dev list <linuxppc-dev@ozlabs•org>
Subject: Re: powerpc: DMA coherent allocations broken for CONFIG_NOT_COHERENT_CACHE
Date: Wed, 27 May 2009 23:34:51 -0400 [thread overview]
Message-ID: <20090527233451.2d02343d@lappy.seanm.ca> (raw)
In-Reply-To: <1243226023.24376.23.camel@pasglop>
On Mon, 25 May 2009 14:33:43 +1000
Benjamin Herrenschmidt <benh@kernel•crashing.org> wrote:
> This is going to .30 if nobody hollers. I've done some testing here
> and it seems to be fine, but more eyes at this stage are much welcome.
Sigh, I didn't get a chance to look at this until tonight. I use
__dma_alloc_coherent in one of the warp drivers because I don't have a
device to pass to dma_alloc_coherent. I was hoping to put it off until
the summer.
I assume I am scuppered without a device:
[ 260.101751] coherent allocation too big (requested 0x5000 mask 0x0)
[ 260.108054] pikadma: Unable to allocate SGL
This is with a NULL passed as the device. And it looks
like if the device is null, it just defaults to ISA_DMA_THRESHOLD,
which is 0 as shown above.
Is there a global platform device or something similar that I can
piggyback off of? There is no bus associated with this driver, so no
device.
Maybe set ISA_DMA_THRESHOLD somewhere? Some platforms seem to set it:
./platforms/52xx/efika.c: ISA_DMA_THRESHOLD = ~0L;
./platforms/amigaone/setup.c: ISA_DMA_THRESHOLD = 0x00ffffff;
./platforms/chrp/setup.c: ISA_DMA_THRESHOLD = ~0L;
./platforms/powermac/setup.c: ISA_DMA_THRESHOLD = ~0L;
So if anybody knows another way around this? The driver is basically
allocating a scatter gather list that is passed to a DMA engine in the
FPGA.
This isn't a showstopper.... we are not planning to move to 2.6.30 in
the near future.
Cheers,
Sean
next prev parent reply other threads:[~2009-05-28 3:34 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-21 16:50 powerpc: DMA coherent allocations broken for CONFIG_NOT_COHERENT_CACHE Albert Herranz
2009-05-24 6:47 ` Grant Likely
2009-05-24 10:21 ` Benjamin Herrenschmidt
2009-05-25 0:21 ` Benjamin Herrenschmidt
2009-05-25 1:43 ` Arnd Bergmann
2009-05-25 4:19 ` Benjamin Herrenschmidt
2009-05-25 4:33 ` Benjamin Herrenschmidt
2009-05-25 5:50 ` Grant Likely
2009-05-25 6:49 ` Benjamin Herrenschmidt
2009-05-28 3:34 ` Sean MacLennan [this message]
2009-05-28 3:42 ` Grant Likely
2009-05-28 5:00 ` Sean MacLennan
2009-05-28 5:09 ` Grant Likely
2009-05-28 3:52 ` Benjamin Herrenschmidt
2009-05-28 4:11 ` Sean MacLennan
2009-05-28 4:19 ` Benjamin Herrenschmidt
-- strict thread matches above, loose matches on Subject: below --
2009-05-26 17:13 Albert Herranz
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=20090527233451.2d02343d@lappy.seanm.ca \
--to=smaclennan@pikatech$(echo .)com \
--cc=benh@kernel$(echo .)crashing.org \
--cc=linuxppc-dev@ozlabs$(echo .)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