Merge tag 'kconfig-v4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy...

[linux.git] / Documentation / DMA-API.txt

diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index ac66ae2509a91c50174f4e21091d025529cfe7fd..e133ccd60228044ac1bce9026082bd5b3eb2411d 100644 (file)
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -58,15 +58,6 @@ specify the ``GFP_`` flags (see kmalloc()) for the allocation (the
 implementation may choose to ignore flags that affect the location of
 the returned memory, like GFP_DMA).
 
-::
-
-       void *
-       dma_zalloc_coherent(struct device *dev, size_t size,
-                           dma_addr_t *dma_handle, gfp_t flag)
-
-Wraps dma_alloc_coherent() and also zeroes the returned memory if the
-allocation attempt succeeded.
-
 ::
 
        void
@@ -717,12 +708,15 @@ dma-api/num_errors                The number in this file shows how many
 dma-api/min_free_entries       This read-only file can be read to get the
                                minimum number of free dma_debug_entries the
                                allocator has ever seen. If this value goes
-                               down to zero the code will disable itself
-                               because it is not longer reliable.
+                               down to zero the code will attempt to increase
+                               nr_total_entries to compensate.
 
 dma-api/num_free_entries       The current number of free dma_debug_entries
                                in the allocator.
 
+dma-api/nr_total_entries       The total number of dma_debug_entries in the
+                               allocator, both free and used.
+
 dma-api/driver-filter          You can write a name of a driver into this file
                                to limit the debug output to requests from that
                                particular driver. Write an empty string to
@@ -742,10 +736,15 @@ driver filter at boot time. The debug code will only print errors for that
 driver afterwards. This filter can be disabled or changed later using debugfs.
 
 When the code disables itself at runtime this is most likely because it ran
-out of dma_debug_entries. These entries are preallocated at boot. The number
-of preallocated entries is defined per architecture. If it is too low for you
-boot with 'dma_debug_entries=<your_desired_number>' to overwrite the
-architectural default.
+out of dma_debug_entries and was unable to allocate more on-demand. 65536
+entries are preallocated at boot - if this is too low for you boot with
+'dma_debug_entries=<your_desired_number>' to overwrite the default. Note
+that the code allocates entries in batches, so the exact number of
+preallocated entries may be greater than the actual number requested. The
+code will print to the kernel log each time it has dynamically allocated
+as many entries as were initially preallocated. This is to indicate that a
+larger preallocation size may be appropriate, or if it happens continually
+that a driver may be leaking mappings.
 
 ::