[PATCH v4 14/43] usb: gadget: composite: introduce clear_alt() operation

[Robert Baldyga <r.baldyga@samsung.com>]

Introduce clear_alt() callback, which is called when prevoiusly set
altsetting is cleared. This can take place in two situations:
- when another altsetting is selected,
- during function disable.

Thanks to symetry to set_alt(), clear_alt() simplifies managing of
resources allocated in set_alt(). It also takes over the function of
disable() opetarion, so it can be removed after converting all USB
functions to new API.

Signed-off-by: Robert Baldyga <r.baldyga@samsung.com>
---
 drivers/usb/gadget/composite.c | 12 ++++++++----
 include/linux/usb/composite.h  |  4 ++++
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 0c962d4..1c26443 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -981,6 +981,9 @@ static void disable_interface(struct usb_function *f, unsigned i)
 	for (e = 0; e < alt->eps_num; ++e)
 		usb_ep_disable(alt->eps[e]->ep);
 
+	if (f->clear_alt)
+		f->clear_alt(f, i, intf->cur_altset);
+
 	intf->cur_altset = -1;
 }
 
@@ -992,12 +995,13 @@ static void disable_function(struct usb_function *f)
 {
 	int i;
 
-	if (usb_function_is_new_api(f))
+	if (usb_function_is_new_api(f)) {
 		for (i = 0; i < f->descs->intfs_num; ++i)
 			disable_interface(f, i);
-
-	if (f->disable)
-		f->disable(f);
+	} else {
+		if (f->disable)
+			f->disable(f);
+	}
 
 	bitmap_zero(f->endpoints, 32);
 }
diff --git a/include/linux/usb/composite.h b/include/linux/usb/composite.h
index e985f3a..aa55377 100644
--- a/include/linux/usb/composite.h
+++ b/include/linux/usb/composite.h
@@ -308,6 +308,8 @@ struct usb_os_desc_table {
  *	initialize usb_ep.driver data at this time (when it is used).
  *	Note that setting an interface to its current altsetting resets
  *	interface state, and that all interfaces have a disabled state.
+ * @clear_alt: (REQUIRED) Clears altsetting, frees all ep requiests and other
+ *	resources allocated by set_alt.
  * @get_alt: Returns the active altsetting.  If this is not provided,
  *	then only altsetting zero is supported.
  * @disable: (REQUIRED) Indicates the function should be disabled.  Reasons
@@ -380,6 +382,8 @@ struct usb_function {
 	/* runtime state management */
 	int			(*set_alt)(struct usb_function *,
 					unsigned interface, unsigned alt);
+	void			(*clear_alt)(struct usb_function *,
+					unsigned interface, unsigned alt);
 	int			(*get_alt)(struct usb_function *,
 					unsigned interface);
 	void			(*disable)(struct usb_function *);
-- 
1.9.1