* [PATCH 1/2] Documentation: DMA API: Be more explicit that nents is always the same
2015-09-23 11:41 [PATCH 0/2] Improve DMA API sg_sync function documentation Sakari Ailus
@ 2015-09-23 11:41 ` Sakari Ailus
2015-09-24 21:51 ` Jonathan Corbet
2015-09-23 11:41 ` [PATCH 2/2] arm: mm: Fix comments in sg_sync functions Sakari Ailus
1 sibling, 1 reply; 5+ messages in thread
From: Sakari Ailus @ 2015-09-23 11:41 UTC (permalink / raw)
To: linux-doc; +Cc: bhelgaas, corbet, linux-kernel, djkurtz, Sakari Ailus
From: Sakari Ailus <sakari.ailus@iki.fi>
The nents argument to the DMA API functions operating on scatterlists is
always the same. The documentation used different argument names and the
matter was not mentioned in Documentation/DMA-API-HOWTO.txt at all. Fix
these.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
Documentation/DMA-API-HOWTO.txt | 5 +++++
Documentation/DMA-API.txt | 6 +++---
2 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/Documentation/DMA-API-HOWTO.txt b/Documentation/DMA-API-HOWTO.txt
index 55b70b9..d69b3fc 100644
--- a/Documentation/DMA-API-HOWTO.txt
+++ b/Documentation/DMA-API-HOWTO.txt
@@ -681,6 +681,11 @@ or:
as appropriate.
+PLEASE NOTE: The 'nents' argument to dma_sync_sg_for_cpu() and
+ dma_sync_sg_for_device() must be the same passed to
+ dma_map_sg(). It is _NOT_ the count returned by
+ dma_map_sg().
+
After the last DMA transfer call one of the DMA unmap routines
dma_unmap_{single,sg}(). If you don't touch the data from the first
dma_map_*() call till dma_unmap_*(), then you don't have to call the
diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index edccacd..8d065d6 100644
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -340,7 +340,7 @@ accessed sg->address and sg->length as shown above.
void
dma_unmap_sg(struct device *dev, struct scatterlist *sg,
- int nhwentries, enum dma_data_direction direction)
+ int nents, enum dma_data_direction direction)
Unmap the previously mapped scatter/gather list. All the parameters
must be the same as those and passed in to the scatter/gather mapping
@@ -356,10 +356,10 @@ void
dma_sync_single_for_device(struct device *dev, dma_addr_t dma_handle, size_t size,
enum dma_data_direction direction)
void
-dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, int nelems,
+dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, int nents,
enum dma_data_direction direction)
void
-dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nelems,
+dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nents,
enum dma_data_direction direction)
Synchronise a single contiguous or scatter/gather mapping for the CPU
--
2.1.0.231.g7484e3b
^ permalink raw reply [flat|nested] 5+ messages in thread* [PATCH 2/2] arm: mm: Fix comments in sg_sync functions
2015-09-23 11:41 [PATCH 0/2] Improve DMA API sg_sync function documentation Sakari Ailus
2015-09-23 11:41 ` [PATCH 1/2] Documentation: DMA API: Be more explicit that nents is always the same Sakari Ailus
@ 2015-09-23 11:41 ` Sakari Ailus
1 sibling, 0 replies; 5+ messages in thread
From: Sakari Ailus @ 2015-09-23 11:41 UTC (permalink / raw)
To: linux-doc; +Cc: bhelgaas, corbet, linux-kernel, djkurtz
The comment on the usage of arm_dma_sync_sg_for_cpu(),
arm_dma_sync_sg_for_device(), arm_iommu_sync_sg_for_cpu() and
arm_iommu_sync_sg_for_device() functions wrongly noted that the "nelems"
parameter is the number of sglist entries returned by dma_map_sg(), while
this must be the number of entiries passed to dma_map_sg() instead.
Suggested-by: Daniel Kurtz <djkurtz@chromium.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
arch/arm/mm/dma-mapping.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index e626043..1c0154a 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -958,7 +958,7 @@ void arm_dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
* arm_dma_sync_sg_for_cpu
* @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
* @sg: list of buffers
- * @nents: number of buffers to map (returned from dma_map_sg)
+ * @nents: number of buffers to sync (same as was passed to dma_map_sg)
* @dir: DMA transfer direction (same as was passed to dma_map_sg)
*/
void arm_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
@@ -977,7 +977,7 @@ void arm_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
* arm_dma_sync_sg_for_device
* @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
* @sg: list of buffers
- * @nents: number of buffers to map (returned from dma_map_sg)
+ * @nents: number of buffers to sync (same as was passed to dma_map_sg)
* @dir: DMA transfer direction (same as was passed to dma_map_sg)
*/
void arm_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
@@ -1672,7 +1672,7 @@ void arm_iommu_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
* arm_iommu_sync_sg_for_cpu
* @dev: valid struct device pointer
* @sg: list of buffers
- * @nents: number of buffers to map (returned from dma_map_sg)
+ * @nents: number of buffers to sync (same as was passed to dma_map_sg)
* @dir: DMA transfer direction (same as was passed to dma_map_sg)
*/
void arm_iommu_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
@@ -1690,7 +1690,7 @@ void arm_iommu_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
* arm_iommu_sync_sg_for_device
* @dev: valid struct device pointer
* @sg: list of buffers
- * @nents: number of buffers to map (returned from dma_map_sg)
+ * @nents: number of buffers to sync (same as was passed to dma_map_sg)
* @dir: DMA transfer direction (same as was passed to dma_map_sg)
*/
void arm_iommu_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
--
2.1.0.231.g7484e3b
^ permalink raw reply [flat|nested] 5+ messages in thread