diff options
Diffstat (limited to 'Documentation/DMA-API.txt')
-rw-r--r-- | Documentation/DMA-API.txt | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt index b462bb149543..52441694fe03 100644 --- a/Documentation/DMA-API.txt +++ b/Documentation/DMA-API.txt | |||
@@ -170,16 +170,15 @@ Returns: 0 if successful and a negative error if not. | |||
170 | u64 | 170 | u64 |
171 | dma_get_required_mask(struct device *dev) | 171 | dma_get_required_mask(struct device *dev) |
172 | 172 | ||
173 | After setting the mask with dma_set_mask(), this API returns the | 173 | This API returns the mask that the platform requires to |
174 | actual mask (within that already set) that the platform actually | 174 | operate efficiently. Usually this means the returned mask |
175 | requires to operate efficiently. Usually this means the returned mask | ||
176 | is the minimum required to cover all of memory. Examining the | 175 | is the minimum required to cover all of memory. Examining the |
177 | required mask gives drivers with variable descriptor sizes the | 176 | required mask gives drivers with variable descriptor sizes the |
178 | opportunity to use smaller descriptors as necessary. | 177 | opportunity to use smaller descriptors as necessary. |
179 | 178 | ||
180 | Requesting the required mask does not alter the current mask. If you | 179 | Requesting the required mask does not alter the current mask. If you |
181 | wish to take advantage of it, you should issue another dma_set_mask() | 180 | wish to take advantage of it, you should issue a dma_set_mask() |
182 | call to lower the mask again. | 181 | call to set the mask to the value returned. |
183 | 182 | ||
184 | 183 | ||
185 | Part Id - Streaming DMA mappings | 184 | Part Id - Streaming DMA mappings |