uwb: avoid radio controller reset loops

If a radio controller reset attempt occurs while a probe() or remove()
is in progress it fails and is retried endlessly, potentially preventing
the probe() or remove() from completing.

If a reset fails, sleep for a bit before retrying the reset.  This
allows the probe()/remove() to complete.
Signed-off-by: David Vrabel <david.vrabel@csr.com>

drivers/uwb/hwa-rc.c

@@ -887,8 +887,7 @@ static int hwarc_post_reset(struct usb_interface *iface)
 	struct hwarc *hwarc = usb_get_intfdata(iface);
 	struct uwb_rc *uwb_rc = hwarc->uwb_rc;
 
-	uwb_rc_post_reset(uwb_rc);
-	return 0;
+	return uwb_rc_post_reset(uwb_rc);
 }
 
 /** USB device ID's that we handle */

drivers/uwb/reset.c

@@ -30,6 +30,7 @@
  */
 #include <linux/kernel.h>
 #include <linux/err.h>
+#include <linux/delay.h>
 
 #include "uwb-internal.h"
 
@@ -323,13 +324,15 @@ int uwbd_msg_handle_reset(struct uwb_event *evt)
 
 	dev_info(&rc->uwb_dev.dev, "resetting radio controller\n");
 	ret = rc->reset(rc);
-	if (ret) {
+	if (ret < 0) {
 		dev_err(&rc->uwb_dev.dev, "failed to reset hardware: %d\n", ret);
 		goto error;
 	}
 	return 0;
 error:
-	/* Nothing can be done except try the reset again. */
+	/* Nothing can be done except try the reset again. Wait a bit
+	   to avoid reset loops during probe() or remove(). */
+	msleep(1000);
 	uwb_rc_reset_all(rc);
 	return ret;
 }
@@ -368,22 +371,20 @@ void uwb_rc_pre_reset(struct uwb_rc *rc)
 }
 EXPORT_SYMBOL_GPL(uwb_rc_pre_reset);
 
-void uwb_rc_post_reset(struct uwb_rc *rc)
+int uwb_rc_post_reset(struct uwb_rc *rc)
 {
 	int ret;
 
 	ret = rc->start(rc);
 	if (ret)
-		goto error;
+		goto out;
 	ret = uwb_rc_mac_addr_set(rc, &rc->uwb_dev.mac_addr);
 	if (ret)
-		goto error;
+		goto out;
 	ret = uwb_rc_dev_addr_set(rc, &rc->uwb_dev.dev_addr);
 	if (ret)
-		goto error;
-	return;
-error:
-	/* Nothing can be done except try the reset again. */
-	uwb_rc_reset_all(rc);
+		goto out;
+out:
+	return ret;
 }
 EXPORT_SYMBOL_GPL(uwb_rc_post_reset);

drivers/uwb/umc-bus.c

@@ -66,7 +66,7 @@ int umc_controller_reset(struct umc_dev *umc)
 		return -EAGAIN;
 	ret = device_for_each_child(parent, parent, umc_bus_pre_reset_helper);
 	if (ret >= 0)
-		device_for_each_child(parent, parent, umc_bus_post_reset_helper);
+		ret = device_for_each_child(parent, parent, umc_bus_post_reset_helper);
 	up(&parent->sem);
 
 	return ret;

drivers/uwb/whc-rc.c

@@ -443,8 +443,7 @@ static int whcrc_post_reset(struct umc_dev *umc)
 	struct whcrc *whcrc = umc_get_drvdata(umc);
 	struct uwb_rc *uwb_rc = whcrc->uwb_rc;
 
-	uwb_rc_post_reset(uwb_rc);
-	return 0;
+	return uwb_rc_post_reset(uwb_rc);
 }
 
 /* PCI device ID's that we handle [so it gets loaded] */

include/linux/uwb.h

@@ -597,7 +597,7 @@ void uwb_rc_neh_grok(struct uwb_rc *, void *, size_t);
 void uwb_rc_neh_error(struct uwb_rc *, int);
 void uwb_rc_reset_all(struct uwb_rc *rc);
 void uwb_rc_pre_reset(struct uwb_rc *rc);
-void uwb_rc_post_reset(struct uwb_rc *rc);
+int uwb_rc_post_reset(struct uwb_rc *rc);
 
 /**
  * uwb_rsv_is_owner - is the owner of this reservation the RC?