wusbcore: add sysfs attribute for retry count

This patch adds a sysfs attribute for the wireless host controller
transaction retry count.  It also changes the default value from 15
retries to infinite retries because the driver currently does not handle
retry errors gracefully.
Signed-off-by: Thomas Pugliese <thomas.pugliese@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/wusbcore/wa-rpipe.c

@@ -367,8 +367,7 @@ static int rpipe_aim(struct wa_rpipe *rpipe, struct wahc *wa,
 	rpipe->descr.bmAttribute = (ep->desc.bmAttributes &
 					USB_ENDPOINT_XFERTYPE_MASK);
 	/* rpipe->descr.bmCharacteristics RO */
-	/* FIXME: bmRetryOptions */
-	rpipe->descr.bmRetryOptions = 15;
+	rpipe->descr.bmRetryOptions = (wa->wusb->retry_count & 0xF);
 	/* FIXME: use for assessing link quality? */
 	rpipe->descr.wNumTransactionErrors = 0;
 	result = __rpipe_set_descr(wa, &rpipe->descr,

drivers/usb/wusbcore/wusbhc.c

@@ -205,12 +205,42 @@ static ssize_t wusb_dnts_store(struct device *dev,
 }
 static DEVICE_ATTR(wusb_dnts, 0644, wusb_dnts_show, wusb_dnts_store);
 
+static ssize_t wusb_retry_count_show(struct device *dev,
+				  struct device_attribute *attr,
+				  char *buf)
+{
+	struct wusbhc *wusbhc = usbhc_dev_to_wusbhc(dev);
+
+	return sprintf(buf, "%d\n", wusbhc->retry_count);
+}
+
+static ssize_t wusb_retry_count_store(struct device *dev,
+				   struct device_attribute *attr,
+				   const char *buf, size_t size)
+{
+	struct wusbhc *wusbhc = usbhc_dev_to_wusbhc(dev);
+	uint8_t retry_count;
+	ssize_t result;
+
+	result = sscanf(buf, "%hhu", &retry_count);
+
+	if (result != 1)
+		return -EINVAL;
+
+	wusbhc->retry_count = max_t(uint8_t, retry_count, WUSB_RETRY_COUNT_MAX);
+
+	return size;
+}
+static DEVICE_ATTR(wusb_retry_count, 0644, wusb_retry_count_show,
+	wusb_retry_count_store);
+
 /* Group all the WUSBHC attributes */
 static struct attribute *wusbhc_attrs[] = {
 		&dev_attr_wusb_trust_timeout.attr,
 		&dev_attr_wusb_chid.attr,
 		&dev_attr_wusb_phy_rate.attr,
 		&dev_attr_wusb_dnts.attr,
+		&dev_attr_wusb_retry_count.attr,
 		NULL,
 };
 
@@ -241,6 +271,7 @@ int wusbhc_create(struct wusbhc *wusbhc)
 	wusbhc->phy_rate = UWB_PHY_RATE_INVALID - 1;
 	wusbhc->dnts_num_slots = 4;
 	wusbhc->dnts_interval = 2;
+	wusbhc->retry_count = WUSB_RETRY_COUNT_INFINITE;
 
 	mutex_init(&wusbhc->mutex);
 	result = wusbhc_mmcie_create(wusbhc);

drivers/usb/wusbcore/wusbhc.h

@@ -69,6 +69,8 @@
  * zone 0.
  */
 #define WUSB_CHANNEL_STOP_DELAY_MS 8
+#define WUSB_RETRY_COUNT_MAX 15
+#define WUSB_RETRY_COUNT_INFINITE 0
 
 /**
  * Wireless USB device
@@ -254,6 +256,7 @@ struct wusbhc {
 	uint8_t phy_rate;
 	uint8_t dnts_num_slots;
 	uint8_t dnts_interval;
+	uint8_t retry_count;
 	struct wuie_host_info *wuie_host_info;
 
 	struct mutex mutex;			/* locks everything else */