diff options
| -rw-r--r-- | Documentation/DMA-attributes.txt | 17 | ||||
| -rw-r--r-- | include/linux/dma-mapping.h | 5 |
2 files changed, 22 insertions, 0 deletions
diff --git a/Documentation/DMA-attributes.txt b/Documentation/DMA-attributes.txt index 2d455a5cf671..98bf7ac29aad 100644 --- a/Documentation/DMA-attributes.txt +++ b/Documentation/DMA-attributes.txt @@ -126,3 +126,20 @@ means that we won't try quite as hard to get them. NOTE: At the moment DMA_ATTR_ALLOC_SINGLE_PAGES is only implemented on ARM, though ARM64 patches will likely be posted soon. + +DMA_ATTR_NO_WARN +---------------- + +This tells the DMA-mapping subsystem to suppress allocation failure reports +(similarly to __GFP_NOWARN). + +On some architectures allocation failures are reported with error messages +to the system logs. Although this can help to identify and debug problems, +drivers which handle failures (eg, retry later) have no problems with them, +and can actually flood the system logs with error messages that aren't any +problem at all, depending on the implementation of the retry mechanism. + +So, this provides a way for drivers to avoid those error messages on calls +where allocation failures are not a problem, and shouldn't bother the logs. + +NOTE: At the moment DMA_ATTR_NO_WARN is only implemented on PowerPC. diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index 0f90eb5e3c6b..08528afdf58b 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -56,6 +56,11 @@ * that gives better TLB efficiency. */ #define DMA_ATTR_ALLOC_SINGLE_PAGES (1UL << 7) +/* + * DMA_ATTR_NO_WARN: This tells the DMA-mapping subsystem to suppress + * allocation failure reports (similarly to __GFP_NOWARN). + */ +#define DMA_ATTR_NO_WARN (1UL << 8) /* * A dma_addr_t can hold any valid DMA or bus address for the platform. |