usb: gadget: f_fs: pull out f->disable() from ffs_func_set_alt()

The ``alt`` parameter was used as a way to differentiate between
f->disable() and f->set_alt(). As the code paths diverge quite a bit,
pull out the f->disable() code from ffs_func_set_alt(), everything will
become clearer and less error prone. No change in functionality
intended.
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Link: https://lore.kernel.org/r/20240802140428.2000312-3-tudor.ambarus@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/function/f_fs.c

@@ -3731,14 +3731,12 @@ static int ffs_func_set_alt(struct usb_function *f,
 	struct ffs_data *ffs = func->ffs;
 	int ret = 0, intf;
 
-	if (alt != (unsigned)-1) {
-		if (alt > MAX_ALT_SETTINGS)
-			return -EINVAL;
+	if (alt > MAX_ALT_SETTINGS)
+		return -EINVAL;
 
-		intf = ffs_func_revmap_intf(func, interface);
-		if (intf < 0)
-			return intf;
-	}
+	intf = ffs_func_revmap_intf(func, interface);
+	if (intf < 0)
+		return intf;
 
 	if (ffs->func)
 		ffs_func_eps_disable(ffs->func);
@@ -3753,12 +3751,6 @@ static int ffs_func_set_alt(struct usb_function *f,
 	if (ffs->state != FFS_ACTIVE)
 		return -ENODEV;
 
-	if (alt == (unsigned)-1) {
-		ffs->func = NULL;
-		ffs_event_add(ffs, FUNCTIONFS_DISABLE);
-		return 0;
-	}
-
 	ffs->func = func;
 	ret = ffs_func_eps_enable(func);
 	if (ret >= 0) {
@@ -3770,7 +3762,23 @@ static int ffs_func_set_alt(struct usb_function *f,
 
 static void ffs_func_disable(struct usb_function *f)
 {
-	ffs_func_set_alt(f, 0, (unsigned)-1);
+	struct ffs_function *func = ffs_func_from_usb(f);
+	struct ffs_data *ffs = func->ffs;
+
+	if (ffs->func)
+		ffs_func_eps_disable(ffs->func);
+
+	if (ffs->state == FFS_DEACTIVATED) {
+		ffs->state = FFS_CLOSING;
+		INIT_WORK(&ffs->reset_work, ffs_reset_work);
+		schedule_work(&ffs->reset_work);
+		return;
+	}
+
+	if (ffs->state == FFS_ACTIVE) {
+		ffs->func = NULL;
+		ffs_event_add(ffs, FUNCTIONFS_DISABLE);
+	}
 }
 
 static int ffs_func_setup(struct usb_function *f,