@@ -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.
@@ -19,6 +19,7 @@ enum dma_attr {
DMA_ATTR_SKIP_CPU_SYNC,
DMA_ATTR_FORCE_CONTIGUOUS,
DMA_ATTR_ALLOC_SINGLE_PAGES,
+ DMA_ATTR_NO_WARN,
DMA_ATTR_MAX,
};
Introduce the DMA_ATTR_NO_WARN attribute, and document it. Signed-off-by: Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com> --- Changelog: v3: - dma: none. v2: - all: address warnings from checkpatch.pl (line wrapping and typos) Documentation/DMA-attributes.txt | 17 +++++++++++++++++ include/linux/dma-attrs.h | 1 + 2 files changed, 18 insertions(+)