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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>
This commit is contained in:
Andrzej Pietrasiewicz 2015-01-19 13:52:58 +01:00 committed by Felipe Balbi
parent 727968357e
commit 578d0b6b61
1 changed files with 34 additions and 0 deletions
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34
drivers/usb/gadget/function/uvc_configfs.c
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@ -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)
{