can: gs_usb: gs_usb_set_phys_id(): return with error if identify is not supported

Until commit 409c188c57cd ("can: tree-wide: advertise software
timestamping capabilities") the ethtool_ops was only assigned for
devices which support the GS_CAN_FEATURE_IDENTIFY feature. That commit
assigns ethtool_ops unconditionally.

This results on controllers without GS_CAN_FEATURE_IDENTIFY support
for the following ethtool error:

| $ ethtool -p can0 1
| Cannot identify NIC: Broken pipe

Restore the correct error value by checking for
GS_CAN_FEATURE_IDENTIFY in the gs_usb_set_phys_id() function.

| $ ethtool -p can0 1
| Cannot identify NIC: Operation not supported

While there use the variable "netdev" for the "struct net_device"
pointer and "dev" for the "struct gs_can" pointer as in the rest of
the driver.

Fixes: 409c188c57cd ("can: tree-wide: advertise software timestamping capabilities")
Link: http://lore.kernel.org/all/20220818143853.2671854-1-mkl@pengutronix.de
Cc: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
index 553e2c7..c1ff3c0 100644 (file)
--- a/drivers/net/can/usb/gs_usb.c
+++ b/drivers/net/can/usb/gs_usb.c
@@ -925,17 +925,21 @@ static int gs_usb_set_identify(struct net_device *netdev, bool do_identify)
 }
 
 /* blink LED's for finding the this interface */
-static int gs_usb_set_phys_id(struct net_device *dev,
+static int gs_usb_set_phys_id(struct net_device *netdev,
                              enum ethtool_phys_id_state state)
 {
+       const struct gs_can *dev = netdev_priv(netdev);
        int rc = 0;
 
+       if (!(dev->feature & GS_CAN_FEATURE_IDENTIFY))
+               return -EOPNOTSUPP;
+
        switch (state) {
        case ETHTOOL_ID_ACTIVE:
-               rc = gs_usb_set_identify(dev, GS_CAN_IDENTIFY_ON);
+               rc = gs_usb_set_identify(netdev, GS_CAN_IDENTIFY_ON);
                break;
        case ETHTOOL_ID_INACTIVE:
-               rc = gs_usb_set_identify(dev, GS_CAN_IDENTIFY_OFF);
+               rc = gs_usb_set_identify(netdev, GS_CAN_IDENTIFY_OFF);
                break;
        default:
                break;
@@ -1072,9 +1076,10 @@ static struct gs_can *gs_make_candev(unsigned int channel,
                dev->feature |= GS_CAN_FEATURE_REQ_USB_QUIRK_LPC546XX |
                        GS_CAN_FEATURE_QUIRK_BREQ_CANTACT_PRO;
 
-       if (le32_to_cpu(dconf->sw_version) > 1)
-               if (feature & GS_CAN_FEATURE_IDENTIFY)
-                       netdev->ethtool_ops = &gs_usb_ethtool_ops;
+       /* GS_CAN_FEATURE_IDENTIFY is only supported for sw_version > 1 */
+       if (!(le32_to_cpu(dconf->sw_version) > 1 &&
+             feature & GS_CAN_FEATURE_IDENTIFY))
+               dev->feature &= ~GS_CAN_FEATURE_IDENTIFY;
 
        kfree(bt_const);