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Re: [PATCH 5/9] MIPS: Convert DMA to use dma-mapping-common.h

To: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Subject: Re: [PATCH 5/9] MIPS: Convert DMA to use dma-mapping-common.h
From: David Daney <ddaney@caviumnetworks.com>
Date: Mon, 27 Sep 2010 10:35:15 -0700
Cc: linux-mips@linux-mips.org, ralf@linux-mips.org, linux-kernel@vger.kernel.org
In-reply-to: <20100927142628X.fujita.tomonori@lab.ntt.co.jp>
References: <1285281496-24696-1-git-send-email-ddaney@caviumnetworks.com> <1285281496-24696-6-git-send-email-ddaney@caviumnetworks.com> <20100927142628X.fujita.tomonori@lab.ntt.co.jp>
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On 09/26/2010 10:30 PM, FUJITA Tomonori wrote:
On Thu, 23 Sep 2010 15:38:12 -0700
David Daney<ddaney@caviumnetworks.com>  wrote:

Use asm-generic/dma-mapping-common.h to handle all DMA mapping
operations and establish a default get_dma_ops() that forwards all
operations to the existing code.

Augment dev_archdata to carry a pointer to the struct dma_map_ops,
allowing DMA operations to be overridden on a per device basis.
Currently this is never filled in, so the default dma_map_ops are
used.  A follow-on patch sets this for Octeon PCI devices.

Also initialize the dma_debug system as it is now used if it is
configured.

Signed-off-by: David Daney<ddaney@caviumnetworks.com>
---
  arch/mips/Kconfig                   |    2 +
  arch/mips/include/asm/device.h      |   15 +++-
  arch/mips/include/asm/dma-mapping.h |  125 +++++++++++++++++--------
  arch/mips/mm/dma-default.c          |  179 +++++++++++++---------------------
  4 files changed, 172 insertions(+), 149 deletions(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 6c33709..e68b89f 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -14,6 +14,8 @@ config MIPS
        select HAVE_KRETPROBES
        select RTC_LIB if !MACH_LOONGSON
        select GENERIC_ATOMIC64 if !64BIT
+       select HAVE_DMA_ATTRS
+       select HAVE_DMA_API_DEBUG

  mainmenu "Linux/MIPS Kernel Configuration"

diff --git a/arch/mips/include/asm/device.h b/arch/mips/include/asm/device.h
index 06746c5..65bf274 100644
--- a/arch/mips/include/asm/device.h
+++ b/arch/mips/include/asm/device.h
@@ -3,4 +3,17 @@
   *
   * This file is released under the GPLv2
   */
-#include<asm-generic/device.h>
+#ifndef _ASM_MIPS_DEVICE_H
+#define _ASM_MIPS_DEVICE_H
+
+struct mips_dma_map_ops;
+
+struct dev_archdata {
+       /* DMA operations on that device */
+       struct mips_dma_map_ops *dma_ops;
+};
+
+struct pdev_archdata {
+};
+
+#endif /* _ASM_MIPS_DEVICE_H*/
diff --git a/arch/mips/include/asm/dma-mapping.h 
b/arch/mips/include/asm/dma-mapping.h
index 18fbf7a..9a4c307 100644
--- a/arch/mips/include/asm/dma-mapping.h
+++ b/arch/mips/include/asm/dma-mapping.h
@@ -5,51 +5,67 @@
  #include<asm/cache.h>
  #include<asm-generic/dma-coherent.h>

-void *dma_alloc_noncoherent(struct device *dev, size_t size,
-                          dma_addr_t *dma_handle, gfp_t flag);
+struct mips_dma_map_ops {
+       struct dma_map_ops dma_map_ops;
+       dma_addr_t (*phys_to_dma)(struct device *dev, phys_addr_t paddr);
+       phys_addr_t (*dma_to_phys)(struct device *dev, dma_addr_t daddr);
+};

The above code doesn't look great but we don't want to add phys_to_dma
and dma_to_phys to dma_map_ops struct, and these functions on MIPS
looks too complicated for ifdef. So I guess that we need to live with
the above code.


I think you have a point here. I will attempt to move these two into a chip specific operations vector, and leave the more generic MIPS version with the simplified static definition.

Thanks,
David Daney

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