From: Christoph Hellwig <hch@lst.de>
To: Tony Luck <tony.luck@intel.com>,
Fenghua Yu <fenghua.yu@intel.com>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
iommu@lists.linux-foundation.org
Cc: linux-ia64@vger.kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org,
Robin Murphy <robin.murphy@arm.com>
Subject: [PATCH 12/12] dma-mapping: move the dma_declare_coherent_memory documentation
Date: Tue, 8 Sep 2020 18:47:58 +0200 [thread overview]
Message-ID: <20200908164758.3177341-13-hch@lst.de> (raw)
In-Reply-To: <20200908164758.3177341-1-hch@lst.de>
dma_declare_coherent_memory should not be in a DMA API guide aimed
at driver writers (that is consumers of the API). Move it to a comment
near the function instead.
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
Documentation/core-api/dma-api.rst | 24 ------------------------
kernel/dma/coherent.c | 17 +++++++++++++++++
2 files changed, 17 insertions(+), 24 deletions(-)
diff --git a/Documentation/core-api/dma-api.rst b/Documentation/core-api/dma-api.rst
index 3b3abbbb4b9a6f..90239348b30f6f 100644
--- a/Documentation/core-api/dma-api.rst
+++ b/Documentation/core-api/dma-api.rst
@@ -586,30 +586,6 @@ the DMA_ATTR_NON_CONSISTENT flag starting at virtual address vaddr and
continuing on for size. Again, you *must* observe the cache line
boundaries when doing this.
-::
-
- int
- dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
- dma_addr_t device_addr, size_t size);
-
-Declare region of memory to be handed out by dma_alloc_coherent() when
-it's asked for coherent memory for this device.
-
-phys_addr is the CPU physical address to which the memory is currently
-assigned (this will be ioremapped so the CPU can access the region).
-
-device_addr is the DMA address the device needs to be programmed
-with to actually address this memory (this will be handed out as the
-dma_addr_t in dma_alloc_coherent()).
-
-size is the size of the area (must be multiples of PAGE_SIZE).
-
-As a simplification for the platforms, only *one* such region of
-memory may be declared per device.
-
-For reasons of efficiency, most platforms choose to track the declared
-region only at the granularity of a page. For smaller allocations,
-you should use the dma_pool() API.
Part III - Debug drivers use of the DMA-API
-------------------------------------------
diff --git a/kernel/dma/coherent.c b/kernel/dma/coherent.c
index 2a0c4985f38e41..f85d14bbfcbe03 100644
--- a/kernel/dma/coherent.c
+++ b/kernel/dma/coherent.c
@@ -107,6 +107,23 @@ static int dma_assign_coherent_memory(struct device *dev,
return 0;
}
+/*
+ * Declare a region of memory to be handed out by dma_alloc_coherent() when it
+ * is asked for coherent memory for this device. This shall only be used
+ * from platform code, usually based on the device tree description.
+ *
+ * phys_addr is the CPU physical address to which the memory is currently
+ * assigned (this will be ioremapped so the CPU can access the region).
+ *
+ * device_addr is the DMA address the device needs to be programmed with to
+ * actually address this memory (this will be handed out as the dma_addr_t in
+ * dma_alloc_coherent()).
+ *
+ * size is the size of the area (must be a multiple of PAGE_SIZE).
+ *
+ * As a simplification for the platforms, only *one* such region of memory may
+ * be declared per device.
+ */
int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
dma_addr_t device_addr, size_t size)
{
--
2.28.0
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next prev parent reply other threads:[~2020-09-08 16:48 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-08 16:47 dma-mapping cleanups Christoph Hellwig
2020-09-08 16:47 ` [PATCH 01/12] MIPS: make dma_sync_*_for_cpu a little less overzealous Christoph Hellwig
2020-09-08 16:47 ` [PATCH 02/12] MIPS/jazzdma: remove the unused vdma_remap function Christoph Hellwig
2020-09-08 16:47 ` [PATCH 03/12] MIPS/jazzdma: decouple from dma-direct Christoph Hellwig
2020-09-08 16:47 ` [PATCH 04/12] dma-mapping: fix DMA_OPS dependencies Christoph Hellwig
2020-09-08 18:04 ` Sergei Shtylyov
2020-09-11 7:10 ` Christoph Hellwig
2020-09-10 12:55 ` Robin Murphy
2020-09-11 7:09 ` Christoph Hellwig
2020-09-08 16:47 ` [PATCH 05/12] dma-mapping: add (back) arch_dma_mark_clean for ia64 Christoph Hellwig
2020-09-08 16:47 ` [PATCH 06/12] dma-direct: remove dma_direct_{alloc,free}_pages Christoph Hellwig
2020-09-10 12:57 ` Robin Murphy
2020-09-08 16:47 ` [PATCH 07/12] dma-direct: lift gfp_t manipulation out of__dma_direct_alloc_pages Christoph Hellwig
2020-09-10 13:02 ` Robin Murphy
2020-09-08 16:47 ` [PATCH 08/12] dma-direct: use phys_to_dma_direct in dma_direct_alloc Christoph Hellwig
2020-09-10 13:03 ` Robin Murphy
2020-09-08 16:47 ` [PATCH 09/12] dma-direct: remove __dma_to_phys Christoph Hellwig
2020-09-10 13:26 ` Robin Murphy
2020-09-11 7:14 ` Christoph Hellwig
2020-09-08 16:47 ` [PATCH 10/12] dma-direct: rename and cleanup __phys_to_dma Christoph Hellwig
2020-09-10 13:30 ` Robin Murphy
2020-09-08 16:47 ` [PATCH 11/12] dma-mapping: move dma_common_{mmap, get_sgtable} out of mapping.c Christoph Hellwig
2020-09-10 13:34 ` Robin Murphy
2020-09-11 7:15 ` [PATCH 11/12] dma-mapping: move dma_common_{mmap,get_sgtable} " Christoph Hellwig
2020-09-08 16:47 ` Christoph Hellwig [this message]
2020-09-10 13:51 ` [PATCH 12/12] dma-mapping: move the dma_declare_coherent_memory documentation Robin Murphy
2020-09-11 7:17 ` Christoph Hellwig
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