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Re: [PATCH 3/3] MIPS: DMA: Add plat_extra_sync_for_cpu()

To: Kevin Cernekee <cernekee@gmail.com>
Subject: Re: [PATCH 3/3] MIPS: DMA: Add plat_extra_sync_for_cpu()
From: David Daney <ddaney@caviumnetworks.com>
Date: Thu, 09 Sep 2010 10:10:00 -0700
Cc: Ralf Baechle <ralf@linux-mips.org>, linux-mips@linux-mips.org, linux-kernel@vger.kernel.org
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On 09/08/2010 04:02 PM, Kevin Cernekee wrote:
On noncoherent processors with a readahead cache, an extra platform-
specific invalidation is required during the dma_sync_*_for_cpu()
operations to keep drivers from seeing stale prefetched data.

Signed-off-by: Kevin Cernekee<cernekee@gmail.com>
---
  .../include/asm/mach-cavium-octeon/dma-coherence.h |   13 +++++++++++++
  arch/mips/include/asm/mach-generic/dma-coherence.h |   13 +++++++++++++
  arch/mips/include/asm/mach-ip27/dma-coherence.h    |   13 +++++++++++++
  arch/mips/include/asm/mach-ip32/dma-coherence.h    |   13 +++++++++++++
  arch/mips/include/asm/mach-jazz/dma-coherence.h    |   13 +++++++++++++
  .../mips/include/asm/mach-loongson/dma-coherence.h |   13 +++++++++++++
  arch/mips/include/asm/mach-powertv/dma-coherence.h |   13 +++++++++++++
  arch/mips/mm/dma-default.c                         |    3 +++
  8 files changed, 94 insertions(+), 0 deletions(-)

[...]

But as far as I can see, none of your plat_extra_sync_for_cpu() do anything.

Perhaps adding this hook should be deferred until there is actually a user.

David Daney

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