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 <plr.vincent@xxxxxxxxx>
---
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 17989b72cdae..2654c4f3c243 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 |
--
2.11.0
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