From 96a420d2d37cc019d0fbb95c9f0e965fa1080e1f Mon Sep 17 00:00:00 2001 From: Vincent Pelletier Date: Thu, 15 Dec 2016 12:47:41 +0000 Subject: [PATCH] usb: gadget: f_fs: Document eventfd effect on descriptor format. When FUNCTIONFS_EVENTFD flag is set, __ffs_data_got_descs reads a 32bits, little-endian value right after the fixed structure header, and passes it to eventfd_ctx_fdget. Document this. Also, rephrase a comment to be affirmative about the role of string descriptor at index 0. Ref: USB 2.0 spec paragraph "9.6.7 String", and also checked to still be current in USB 3.0 spec paragraph "9.6.9 String". Signed-off-by: Vincent Pelletier Signed-off-by: Felipe Balbi --- drivers/usb/gadget/function/f_fs.c | 4 ++-- include/uapi/linux/usb/functionfs.h | 1 + 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c index aab3fc1dbb94..818f4997c1ac 100644 --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -2091,8 +2091,8 @@ static int __ffs_data_do_entity(enum ffs_entity_type type, case FFS_STRING: /* - * Strings are indexed from 1 (0 is magic ;) reserved - * for languages list or some such) + * Strings are indexed from 1 (0 is reserved + * for languages list) */ if (*valuep > helper->ffs->strings_count) helper->ffs->strings_count = *valuep; diff --git a/include/uapi/linux/usb/functionfs.h b/include/uapi/linux/usb/functionfs.h index acc63697a0cc..b2a31a55a612 100644 --- a/include/uapi/linux/usb/functionfs.h +++ b/include/uapi/linux/usb/functionfs.h @@ -93,6 +93,7 @@ struct usb_ext_prop_desc { * | 0 | magic | LE32 | FUNCTIONFS_DESCRIPTORS_MAGIC_V2 | * | 4 | length | LE32 | length of the whole data chunk | * | 8 | flags | LE32 | combination of functionfs_flags | + * | | eventfd | LE32 | eventfd file descriptor | * | | fs_count | LE32 | number of full-speed descriptors | * | | hs_count | LE32 | number of high-speed descriptors | * | | ss_count | LE32 | number of super-speed descriptors | -- 2.39.5