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authorAndrzej Pietrasiewicz <andrzej.p@samsung.com>2015-01-19 15:52:58 +0300
committerFelipe Balbi <balbi@ti.com>2015-01-27 19:00:27 +0300
commit578d0b6b6171e7a7afa49e74f87c683297e9cae9 (patch)
treea9e3cadb28568118e0a592ff73232bd1898d54f0 /drivers/usb/gadget/function/uvc_configfs.c
parent727968357eb84497ac8e2514cf06be3d8779d24f (diff)
downloadlinux-578d0b6b6171e7a7afa49e74f87c683297e9cae9.tar.xz
usb: gadget: uvc: comments for iterating over streaming hierarchy
The purpose of the functions and their parametrs might not be obvious to the reader, so explain it. Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com> Signed-off-by: Felipe Balbi <balbi@ti.com>
Diffstat (limited to 'drivers/usb/gadget/function/uvc_configfs.c')
-rw-r--r--drivers/usb/gadget/function/uvc_configfs.c34
1 files changed, 34 insertions, 0 deletions
diff --git a/drivers/usb/gadget/function/uvc_configfs.c b/drivers/usb/gadget/function/uvc_configfs.c
index 51d8e9ee5323..3c0467bcb14f 100644
--- a/drivers/usb/gadget/function/uvc_configfs.c
+++ b/drivers/usb/gadget/function/uvc_configfs.c
@@ -1918,6 +1918,25 @@ enum uvcg_strm_type {
UVCG_FRAME
};
+/*
+ * Iterate over a hierarchy of streaming descriptors' config items.
+ * The items are created by the user with configfs.
+ *
+ * It "processes" the header pointed to by @priv1, then for each format
+ * that follows the header "processes" the format itself and then for
+ * each frame inside a format "processes" the frame.
+ *
+ * As a "processing" function the @fun is used.
+ *
+ * __uvcg_iter_strm_cls() is used in two context: first, to calculate
+ * the amount of memory needed for an array of streaming descriptors
+ * and second, to actually fill the array.
+ *
+ * @h: streaming header pointer
+ * @priv2: an "inout" parameter (the caller might want to see the changes to it)
+ * @priv3: an "inout" parameter (the caller might want to see the changes to it)
+ * @fun: callback function for processing each level of the hierarchy
+ */
static int __uvcg_iter_strm_cls(struct uvcg_streaming_header *h,
void *priv2, void *priv3,
int (*fun)(void *, void *, void *, int, enum uvcg_strm_type type))
@@ -1951,6 +1970,14 @@ static int __uvcg_iter_strm_cls(struct uvcg_streaming_header *h,
return ret;
}
+/*
+ * Count how many bytes are needed for an array of streaming descriptors.
+ *
+ * @priv1: pointer to a header, format or frame
+ * @priv2: inout parameter, accumulated size of the array
+ * @priv3: inout parameter, accumulated number of the array elements
+ * @n: unused, this function's prototype must match @fun in __uvcg_iter_strm_cls
+ */
static int __uvcg_cnt_strm(void *priv1, void *priv2, void *priv3, int n,
enum uvcg_strm_type type)
{
@@ -2000,6 +2027,13 @@ static int __uvcg_cnt_strm(void *priv1, void *priv2, void *priv3, int n,
return 0;
}
+/*
+ * Fill an array of streaming descriptors.
+ *
+ * @priv1: pointer to a header, format or frame
+ * @priv2: inout parameter, pointer into a block of memory
+ * @priv3: inout parameter, pointer to a 2-dimensional array
+ */
static int __uvcg_fill_strm(void *priv1, void *priv2, void *priv3, int n,
enum uvcg_strm_type type)
{