USB: cdc-acm: clean up no-union-descriptor handling

For interfaces that lack a union descriptor, probe for a
"combined-interface" before falling back to the call-management
descriptor instead of the other way round.

This allows for the removal of the NO_DATA_INTERFACE quirk and makes the
probe algorithm somewhat easier to follow.

Acked-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20200921135951.24045-5-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index cd738fbbe59b7e1836da19c14c6b4268ad1c965b..1d301b92de2ddf3f26c60fe83950db39f806f10d 100644 (file)
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -1219,26 +1219,19 @@ static int acm_probe(struct usb_interface *intf,
                call_intf_num = cmgmd->bDataInterface;
 
        if (!union_header) {
-               if (call_intf_num > 0) {
+               if (intf->cur_altsetting->desc.bNumEndpoints == 3) {
+                       dev_dbg(&intf->dev, "No union descriptor, assuming single interface\n");
+                       combined_interfaces = 1;
+                       control_interface = data_interface = intf;
+                       goto look_for_collapsed_interface;
+               } else if (call_intf_num > 0) {
                        dev_dbg(&intf->dev, "No union descriptor, using call management descriptor\n");
-                       /* quirks for Droids MuIn LCD */
-                       if (quirks & NO_DATA_INTERFACE) {
-                               data_interface = usb_ifnum_to_if(usb_dev, 0);
-                       } else {
-                               data_intf_num = call_intf_num;
-                               data_interface = usb_ifnum_to_if(usb_dev, data_intf_num);
-                       }
+                       data_intf_num = call_intf_num;
+                       data_interface = usb_ifnum_to_if(usb_dev, data_intf_num);
                        control_interface = intf;
                } else {
-                       if (intf->cur_altsetting->desc.bNumEndpoints != 3) {
-                               dev_dbg(&intf->dev,"No union descriptor, giving up\n");
-                               return -ENODEV;
-                       } else {
-                               dev_warn(&intf->dev,"No union descriptor, testing for castrated device\n");
-                               combined_interfaces = 1;
-                               control_interface = data_interface = intf;
-                               goto look_for_collapsed_interface;
-                       }
+                       dev_dbg(&intf->dev, "No union descriptor, giving up\n");
+                       return -ENODEV;
                }
        } else {
                int class = -1;
@@ -1882,11 +1875,6 @@ static const struct usb_device_id acm_ids[] = {
 
        /* NOTE: non-Nokia COMM/ACM/0xff is likely MSFT RNDIS... NOT a modem! */
 
-       /* Support for Droids MuIn LCD */
-       { USB_DEVICE(0x04d8, 0x000b),
-       .driver_info = NO_DATA_INTERFACE,
-       },
-
 #if IS_ENABLED(CONFIG_INPUT_IMS_PCU)
        { USB_DEVICE(0x04d8, 0x0082),   /* Application mode */
        .driver_info = IGNORE_DEVICE,

diff --git a/drivers/usb/class/cdc-acm.h b/drivers/usb/class/cdc-acm.h
index 96331c81550ed77dd3185c76d8ed3be3d5760f02..9dce179d031bb0d7e455c44aea13dedab112d8d3 100644 (file)
--- a/drivers/usb/class/cdc-acm.h
+++ b/drivers/usb/class/cdc-acm.h
@@ -135,9 +135,8 @@ struct acm {
 #define NO_UNION_NORMAL                        BIT(0)
 #define SINGLE_RX_URB                  BIT(1)
 #define NO_CAP_LINE                    BIT(2)
-#define NO_DATA_INTERFACE              BIT(4)
-#define IGNORE_DEVICE                  BIT(5)
-#define QUIRK_CONTROL_LINE_STATE       BIT(6)
-#define CLEAR_HALT_CONDITIONS          BIT(7)
-#define SEND_ZERO_PACKET               BIT(8)
-#define DISABLE_ECHO                   BIT(9)
+#define IGNORE_DEVICE                  BIT(3)
+#define QUIRK_CONTROL_LINE_STATE       BIT(4)
+#define CLEAR_HALT_CONDITIONS          BIT(5)
+#define SEND_ZERO_PACKET               BIT(6)
+#define DISABLE_ECHO                   BIT(7)