releases/3.2.2/rt2800pci-fix-spurious-interrupts-generation.patch

From dfd00c4c8f3dfa1fd7cec45f83d98b2a49743dcd Mon Sep 17 00:00:00 2001
From: Stanislaw Gruszka <sgruszka@redhat.com>
Date: Fri, 13 Jan 2012 12:59:32 +0100
Subject: rt2800pci: fix spurious interrupts generation

From: Stanislaw Gruszka <sgruszka@redhat.com>

commit dfd00c4c8f3dfa1fd7cec45f83d98b2a49743dcd upstream.

Same devices can generate interrupt without properly setting bit in
INT_SOURCE_CSR register (spurious interrupt), what will cause IRQ line
will be disabled by interrupts controller driver.

We discovered that clearing INT_MASK_CSR stops such behaviour. We
previously first read that register, and then clear all know interrupt
sources bits and do not touch reserved bits. After this patch, we write
to all register content (I believe writing to reserved bits on that
register will not cause any problems, I tested that on my rt2800pci
device).

This fix very bad performance problem, practically making device
unusable (since worked without interrupts), reported in:
https://bugzilla.redhat.com/show_bug.cgi?id=658451

We previously tried to workaround that issue in commit
4ba7d9997869d25bd223dea7536fc1ce9fab3b3b "rt2800pci: handle spurious
interrupts", but it was reverted in commit
82e5fc2a34fa9ffea38f00c4066b7e600a0ca5e6
as thing, that will prevent to detect real spurious interrupts.

Reported-and-tested-by: Amir Hedayaty <hedayaty@gmail.com>
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Gertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 drivers/net/wireless/rt2x00/rt2800pci.c |   28 ++++++++--------------------
 1 file changed, 8 insertions(+), 20 deletions(-)

--- a/drivers/net/wireless/rt2x00/rt2800pci.c
+++ b/drivers/net/wireless/rt2x00/rt2800pci.c
@@ -422,7 +422,6 @@ static int rt2800pci_init_queues(struct
 static void rt2800pci_toggle_irq(struct rt2x00_dev *rt2x00dev,
 				 enum dev_state state)
 {
-	int mask = (state == STATE_RADIO_IRQ_ON);
 	u32 reg;
 	unsigned long flags;
 
@@ -436,25 +435,14 @@ static void rt2800pci_toggle_irq(struct
 	}
 
 	spin_lock_irqsave(&rt2x00dev->irqmask_lock, flags);
-	rt2x00pci_register_read(rt2x00dev, INT_MASK_CSR, &reg);
-	rt2x00_set_field32(&reg, INT_MASK_CSR_RXDELAYINT, 0);
-	rt2x00_set_field32(&reg, INT_MASK_CSR_TXDELAYINT, 0);
-	rt2x00_set_field32(&reg, INT_MASK_CSR_RX_DONE, mask);
-	rt2x00_set_field32(&reg, INT_MASK_CSR_AC0_DMA_DONE, 0);
-	rt2x00_set_field32(&reg, INT_MASK_CSR_AC1_DMA_DONE, 0);
-	rt2x00_set_field32(&reg, INT_MASK_CSR_AC2_DMA_DONE, 0);
-	rt2x00_set_field32(&reg, INT_MASK_CSR_AC3_DMA_DONE, 0);
-	rt2x00_set_field32(&reg, INT_MASK_CSR_HCCA_DMA_DONE, 0);
-	rt2x00_set_field32(&reg, INT_MASK_CSR_MGMT_DMA_DONE, 0);
-	rt2x00_set_field32(&reg, INT_MASK_CSR_MCU_COMMAND, 0);
-	rt2x00_set_field32(&reg, INT_MASK_CSR_RXTX_COHERENT, 0);
-	rt2x00_set_field32(&reg, INT_MASK_CSR_TBTT, mask);
-	rt2x00_set_field32(&reg, INT_MASK_CSR_PRE_TBTT, mask);
-	rt2x00_set_field32(&reg, INT_MASK_CSR_TX_FIFO_STATUS, mask);
-	rt2x00_set_field32(&reg, INT_MASK_CSR_AUTO_WAKEUP, mask);
-	rt2x00_set_field32(&reg, INT_MASK_CSR_GPTIMER, 0);
-	rt2x00_set_field32(&reg, INT_MASK_CSR_RX_COHERENT, 0);
-	rt2x00_set_field32(&reg, INT_MASK_CSR_TX_COHERENT, 0);
+	reg = 0;
+	if (state == STATE_RADIO_IRQ_ON) {
+		rt2x00_set_field32(&reg, INT_MASK_CSR_RX_DONE, 1);
+		rt2x00_set_field32(&reg, INT_MASK_CSR_TBTT, 1);
+		rt2x00_set_field32(&reg, INT_MASK_CSR_PRE_TBTT, 1);
+		rt2x00_set_field32(&reg, INT_MASK_CSR_TX_FIFO_STATUS, 1);
+		rt2x00_set_field32(&reg, INT_MASK_CSR_AUTO_WAKEUP, 1);
+	}
 	rt2x00pci_register_write(rt2x00dev, INT_MASK_CSR, reg);
 	spin_unlock_irqrestore(&rt2x00dev->irqmask_lock, flags);