From: Arnd Bergmann <arnd@arndb•de>
To: linuxppc-dev@ozlabs•org
Cc: Albert Herranz <albert_herranz@yahoo•es>, Ilya Yanok <yanok@emcraft•com>
Subject: Re: powerpc: DMA coherent allocations broken for CONFIG_NOT_COHERENT_CACHE
Date: Mon, 25 May 2009 02:43:14 +0100 [thread overview]
Message-ID: <200905250243.15436.arnd@arndb.de> (raw)
In-Reply-To: <1243210914.24376.11.camel@pasglop>
On Monday 25 May 2009, Benjamin Herrenschmidt wrote:
> Note that I still think the right approach in the long run is to ban the
> consistent allocs from atomic contexts generically in linux, though that
> will be a hard nut to crack.
I might be missing too much context here, but can't we make drivers that
need this allocate an uncached memory range at setup time and call
dma_declare_coherent_memory() on that to make a later dma_alloc_coherent()
succeed without GFP_KERNEL?
If that is not enough, dma_alloc_coherent could be changed to
try dma_alloc_from_coherent() on the bridge device (PCI HB,
PLB4, ...), if we reserve a reasonably sized amount of uncached
memory for each bridge that has noncoherent devices.
Arnd <><
next prev parent reply other threads:[~2009-05-25 1:44 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 [this message]
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
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
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