scsi: cxlflash: Support up to 4 ports

[mirror_ubuntu-zesty-kernel.git] / Documentation / sync_file.txt

diff --git a/Documentation/sync_file.txt b/Documentation/sync_file.txt
index e8e2ebafe5fa0ea350af12b5103788e3d04de268..269681a6faec818ddf839c4f1c573ef9415478d4 100644 (file)
--- a/Documentation/sync_file.txt
+++ b/Documentation/sync_file.txt
@@ -6,7 +6,7 @@
 
 This document serves as a guide for device drivers writers on what the
 sync_file API is, and how drivers can support it. Sync file is the carrier of
-the fences(struct fence) that are needed to synchronize between drivers or
+the fences(struct dma_fence) that are needed to synchronize between drivers or
 across process boundaries.
 
 The sync_file API is meant to be used to send and receive fence information
@@ -32,9 +32,9 @@ in-fences and out-fences
 Sync files can go either to or from userspace. When a sync_file is sent from
 the driver to userspace we call the fences it contains 'out-fences'. They are
 related to a buffer that the driver is processing or is going to process, so
-the driver creates an out-fence to be able to notify, through fence_signal(),
-when it has finished using (or processing) that buffer. Out-fences are fences
-that the driver creates.
+the driver creates an out-fence to be able to notify, through
+dma_fence_signal(), when it has finished using (or processing) that buffer.
+Out-fences are fences that the driver creates.
 
 On the other hand if the driver receives fence(s) through a sync_file from
 userspace we call these fence(s) 'in-fences'. Receiveing in-fences means that
@@ -47,7 +47,7 @@ Creating Sync Files
 When a driver needs to send an out-fence userspace it creates a sync_file.
 
 Interface:
-       struct sync_file *sync_file_create(struct fence *fence);
+       struct sync_file *sync_file_create(struct dma_fence *fence);
 
 The caller pass the out-fence and gets back the sync_file. That is just the
 first step, next it needs to install an fd on sync_file->file. So it gets an
@@ -64,6 +64,20 @@ The sync_file fd now can be sent to userspace.
 If the creation process fail, or the sync_file needs to be released by any
 other reason fput(sync_file->file) should be used.
 
+Receiving Sync Files from Userspace
+-----------------------------------
+
+When userspace needs to send an in-fence to the driver it passes file descriptor
+of the Sync File to the kernel. The kernel can then retrieve the fences
+from it.
+
+Interface:
+       struct dma_fence *sync_file_get_fence(int fd);
+
+
+The returned reference is owned by the caller and must be disposed of
+afterwards using dma_fence_put(). In case of error, a NULL is returned instead.
+
 References:
 [1] struct sync_file in include/linux/sync_file.h
 [2] All interfaces mentioned above defined in include/linux/sync_file.h