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From 5e67d4f8a46d19748b501c2ef86de3f50d3cfd51 Mon Sep 17 00:00:00 2001
From: Gabor Juhos <juhosg@openwrt.org>
Date: Sun, 24 Mar 2013 19:26:27 +0100
Subject: [PATCH] rt2x00: rt2800mmio: add a workaround for spurious
TX_FIFO_STATUS interrupts
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
---
drivers/net/wireless/ralink/rt2x00/rt2800mmio.c | 72 +++++++++++++++++++++++++-----
drivers/net/wireless/ralink/rt2x00/rt2x00.h | 5 +++
2 files changed, 65 insertions(+), 12 deletions(-)
--- a/drivers/net/wireless/ralink/rt2x00/rt2800mmio.c
+++ b/drivers/net/wireless/ralink/rt2x00/rt2800mmio.c
@@ -415,9 +415,9 @@ void rt2800mmio_autowake_tasklet(unsigne
}
EXPORT_SYMBOL_GPL(rt2800mmio_autowake_tasklet);
-static void rt2800mmio_txstatus_interrupt(struct rt2x00_dev *rt2x00dev)
+static void rt2800mmio_txstatus_interrupt(struct rt2x00_dev *rt2x00dev,
+ u32 status)
{
- u32 status;
int i;
/*
@@ -438,29 +438,77 @@ static void rt2800mmio_txstatus_interrup
* Since we have only one producer and one consumer we don't
* need to lock the kfifo.
*/
- for (i = 0; i < rt2x00dev->tx->limit; i++) {
- rt2x00mmio_register_read(rt2x00dev, TX_STA_FIFO, &status);
-
- if (!rt2x00_get_field32(status, TX_STA_FIFO_VALID))
- break;
-
+ i = 0;
+ do {
if (!kfifo_put(&rt2x00dev->txstatus_fifo, status)) {
- rt2x00_warn(rt2x00dev, "TX status FIFO overrun, drop tx status report\n");
+ rt2x00_warn(rt2x00dev,
+ "TX status FIFO overrun, drop TX status report\n");
break;
}
- }
+
+ if (++i >= rt2x00dev->tx->limit)
+ break;
+
+ rt2x00mmio_register_read(rt2x00dev, TX_STA_FIFO, &status);
+ } while (rt2x00_get_field32(status, TX_STA_FIFO_VALID));
/* Schedule the tasklet for processing the tx status. */
tasklet_schedule(&rt2x00dev->txstatus_tasklet);
}
+#define RT2800MMIO_TXSTATUS_IRQ_MAX_RETRIES 4
+
+static bool rt2800mmio_txstatus_is_spurious(struct rt2x00_dev *rt2x00dev,
+ u32 txstatus)
+{
+ if (likely(rt2x00_get_field32(txstatus, TX_STA_FIFO_VALID))) {
+ rt2x00dev->txstatus_irq_retries = 0;
+ return false;
+ }
+
+ rt2x00dev->txstatus_irq_retries++;
+
+ /* Ensure that we don't go into an infinite IRQ loop. */
+ if (rt2x00dev->txstatus_irq_retries >=
+ RT2800MMIO_TXSTATUS_IRQ_MAX_RETRIES) {
+ rt2x00_warn(rt2x00dev,
+ "%u spurious TX_FIFO_STATUS interrupt(s)\n",
+ rt2x00dev->txstatus_irq_retries);
+ rt2x00dev->txstatus_irq_retries = 0;
+ return false;
+ }
+
+ return true;
+}
+
irqreturn_t rt2800mmio_interrupt(int irq, void *dev_instance)
{
struct rt2x00_dev *rt2x00dev = dev_instance;
u32 reg, mask;
+ u32 txstatus = 0;
- /* Read status and ACK all interrupts */
+ /* Read status */
rt2x00mmio_register_read(rt2x00dev, INT_SOURCE_CSR, ®);
+
+ if (rt2x00_get_field32(reg, INT_SOURCE_CSR_TX_FIFO_STATUS)) {
+ /* Due to unknown reason the hardware generates a
+ * TX_FIFO_STATUS interrupt before the TX_STA_FIFO
+ * register contain valid data. Read the TX status
+ * here to see if we have to process the actual
+ * request.
+ */
+ rt2x00mmio_register_read(rt2x00dev, TX_STA_FIFO, &txstatus);
+ if (rt2800mmio_txstatus_is_spurious(rt2x00dev, txstatus)) {
+ /* Remove the TX_FIFO_STATUS bit so it won't be
+ * processed in this turn. The hardware will
+ * generate another IRQ for us.
+ */
+ rt2x00_set_field32(®,
+ INT_SOURCE_CSR_TX_FIFO_STATUS, 0);
+ }
+ }
+
+ /* ACK interrupts */
rt2x00mmio_register_write(rt2x00dev, INT_SOURCE_CSR, reg);
if (!reg)
@@ -477,7 +525,7 @@ irqreturn_t rt2800mmio_interrupt(int irq
mask = ~reg;
if (rt2x00_get_field32(reg, INT_SOURCE_CSR_TX_FIFO_STATUS)) {
- rt2800mmio_txstatus_interrupt(rt2x00dev);
+ rt2800mmio_txstatus_interrupt(rt2x00dev, txstatus);
/*
* Never disable the TX_FIFO_STATUS interrupt.
*/
--- a/drivers/net/wireless/ralink/rt2x00/rt2x00.h
+++ b/drivers/net/wireless/ralink/rt2x00/rt2x00.h
@@ -991,6 +991,11 @@ struct rt2x00_dev {
int rf_channel;
/*
+ * Counter for tx status irq retries (rt2800pci).
+ */
+ unsigned int txstatus_irq_retries;
+
+ /*
* Protect the interrupt mask register.
*/
spinlock_t irqmask_lock;
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