usb: gadget: uvc: Fix string descriptor STALL issue when multiple uvc functions are added to a configuration

This patch solved the string descriptor STALL issue when we add multiple UVC
functions in a single configuration using a 'webcam.c' like composite driver.

Signed-off-by: Bhupesh Sharma <bhupesh.sharma@st.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

1 files changed, 22 insertions, 16 deletions

diff --git a/drivers/usb/gadget/f_uvc.c b/drivers/usb/gadget/f_uvc.c
index 2022fe492148..054c35a22fbf 100644
--- a/drivers/usb/gadget/f_uvc.c
+++ b/drivers/usb/gadget/f_uvc.c
@@ -619,22 +619,28 @@ uvc_bind_config(struct usb_configuration *c,
         uvc->desc.fs_streaming = fs_streaming;
         uvc->desc.hs_streaming = hs_streaming;
 
-        /* Allocate string descriptor numbers. */
-        if ((ret = usb_string_id(c->cdev)) < 0)
-                goto error;
-        uvc_en_us_strings[UVC_STRING_ASSOCIATION_IDX].id = ret;
-        uvc_iad.iFunction = ret;
-
-        if ((ret = usb_string_id(c->cdev)) < 0)
-                goto error;
-        uvc_en_us_strings[UVC_STRING_CONTROL_IDX].id = ret;
-        uvc_control_intf.iInterface = ret;
-
-        if ((ret = usb_string_id(c->cdev)) < 0)
-                goto error;
-        uvc_en_us_strings[UVC_STRING_STREAMING_IDX].id = ret;
-        uvc_streaming_intf_alt0.iInterface = ret;
-        uvc_streaming_intf_alt1.iInterface = ret;
+        /* maybe allocate device-global string IDs, and patch descriptors */
+        if (uvc_en_us_strings[UVC_STRING_ASSOCIATION_IDX].id == 0) {
+                /* Allocate string descriptor numbers. */
+                ret = usb_string_id(c->cdev);
+                if (ret < 0)
+                        goto error;
+                uvc_en_us_strings[UVC_STRING_ASSOCIATION_IDX].id = ret;
+                uvc_iad.iFunction = ret;
+
+                ret = usb_string_id(c->cdev);
+                if (ret < 0)
+                        goto error;
+                uvc_en_us_strings[UVC_STRING_CONTROL_IDX].id = ret;
+                uvc_control_intf.iInterface = ret;
+
+                ret = usb_string_id(c->cdev);
+                if (ret < 0)
+                        goto error;
+                uvc_en_us_strings[UVC_STRING_STREAMING_IDX].id = ret;
+                uvc_streaming_intf_alt0.iInterface = ret;
+                uvc_streaming_intf_alt1.iInterface = ret;
+        }
 
         /* Register the function. */
         uvc->func.name = "uvc";