package/kernel/mac80211/patches/600-0034-rt2x00-rt2800mmio-add-a-workaround-for-spurious-TX_F.patch

   1 From 5e67d4f8a46d19748b501c2ef86de3f50d3cfd51 Mon Sep 17 00:00:00 2001
   2 From: Gabor Juhos <juhosg@openwrt.org>
   3 Date: Sun, 24 Mar 2013 19:26:27 +0100
   4 Subject: [PATCH] rt2x00: rt2800mmio: add a workaround for spurious
   5  TX_FIFO_STATUS interrupts
   6
   7 Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
   8 ---
   9  drivers/net/wireless/ralink/rt2x00/rt2800mmio.c |   72 +++++++++++++++++++++++++-----
  10  drivers/net/wireless/ralink/rt2x00/rt2x00.h     |    5 +++
  11  2 files changed, 65 insertions(+), 12 deletions(-)
  12
  13 --- a/drivers/net/wireless/ralink/rt2x00/rt2800mmio.c
  14 +++ b/drivers/net/wireless/ralink/rt2x00/rt2800mmio.c
  15 @@ -415,9 +415,9 @@ void rt2800mmio_autowake_tasklet(unsigne
  16  }
  17  EXPORT_SYMBOL_GPL(rt2800mmio_autowake_tasklet);
  18
  19 -static void rt2800mmio_txstatus_interrupt(struct rt2x00_dev *rt2x00dev)
  20 +static void rt2800mmio_txstatus_interrupt(struct rt2x00_dev *rt2x00dev,
  21 +                                         u32 status)
  22  {
  23 -       u32 status;
  24         int i;
  25
  26         /*
  27 @@ -438,29 +438,77 @@ static void rt2800mmio_txstatus_interrup
  28          * Since we have only one producer and one consumer we don't
  29          * need to lock the kfifo.
  30          */
  31 -       for (i = 0; i < rt2x00dev->tx->limit; i++) {
  32 -               rt2x00mmio_register_read(rt2x00dev, TX_STA_FIFO, &status);
  33 -
  34 -               if (!rt2x00_get_field32(status, TX_STA_FIFO_VALID))
  35 -                       break;
  36 -
  37 +       i = 0;
  38 +       do {
  39                 if (!kfifo_put(&rt2x00dev->txstatus_fifo, status)) {
  40 -                       rt2x00_warn(rt2x00dev, "TX status FIFO overrun, drop tx status report\n");
  41 +                       rt2x00_warn(rt2x00dev,
  42 +                                   "TX status FIFO overrun, drop TX status report\n");
  43                         break;
  44                 }
  45 -       }
  46 +
  47 +               if (++i >= rt2x00dev->tx->limit)
  48 +                       break;
  49 +
  50 +               rt2x00mmio_register_read(rt2x00dev, TX_STA_FIFO, &status);
  51 +       } while (rt2x00_get_field32(status, TX_STA_FIFO_VALID));
  52
  53         /* Schedule the tasklet for processing the tx status. */
  54         tasklet_schedule(&rt2x00dev->txstatus_tasklet);
  55  }
  56
  57 +#define RT2800MMIO_TXSTATUS_IRQ_MAX_RETRIES    4
  58 +
  59 +static bool rt2800mmio_txstatus_is_spurious(struct rt2x00_dev *rt2x00dev,
  60 +                                          u32 txstatus)
  61 +{
  62 +       if (likely(rt2x00_get_field32(txstatus, TX_STA_FIFO_VALID))) {
  63 +               rt2x00dev->txstatus_irq_retries = 0;
  64 +               return false;
  65 +       }
  66 +
  67 +       rt2x00dev->txstatus_irq_retries++;
  68 +
  69 +       /* Ensure that we don't go into an infinite IRQ loop. */
  70 +       if (rt2x00dev->txstatus_irq_retries >=
  71 +           RT2800MMIO_TXSTATUS_IRQ_MAX_RETRIES) {
  72 +               rt2x00_warn(rt2x00dev,
  73 +                           "%u spurious TX_FIFO_STATUS interrupt(s)\n",
  74 +                           rt2x00dev->txstatus_irq_retries);
  75 +               rt2x00dev->txstatus_irq_retries = 0;
  76 +               return false;
  77 +       }
  78 +
  79 +       return true;
  80 +}
  81 +
  82  irqreturn_t rt2800mmio_interrupt(int irq, void *dev_instance)
  83  {
  84         struct rt2x00_dev *rt2x00dev = dev_instance;
  85         u32 reg, mask;
  86 +       u32 txstatus = 0;
  87
  88 -       /* Read status and ACK all interrupts */
  89 +       /* Read status */
  90         rt2x00mmio_register_read(rt2x00dev, INT_SOURCE_CSR, &reg);
  91 +
  92 +       if (rt2x00_get_field32(reg, INT_SOURCE_CSR_TX_FIFO_STATUS)) {
  93 +               /* Due to unknown reason the hardware generates a
  94 +                * TX_FIFO_STATUS interrupt before the TX_STA_FIFO
  95 +                * register contain valid data. Read the TX status
  96 +                * here to see if we have to process the actual
  97 +                * request.
  98 +                */
  99 +               rt2x00mmio_register_read(rt2x00dev, TX_STA_FIFO, &txstatus);
 100 +               if (rt2800mmio_txstatus_is_spurious(rt2x00dev, txstatus)) {
 101 +                       /* Remove the TX_FIFO_STATUS bit so it won't be
 102 +                        * processed in this turn. The hardware will
 103 +                        * generate another IRQ for us.
 104 +                        */
 105 +                       rt2x00_set_field32(&reg,
 106 +                                          INT_SOURCE_CSR_TX_FIFO_STATUS, 0);
 107 +               }
 108 +       }
 109 +
 110 +       /* ACK interrupts */
 111         rt2x00mmio_register_write(rt2x00dev, INT_SOURCE_CSR, reg);
 112
 113         if (!reg)
 114 @@ -477,7 +525,7 @@ irqreturn_t rt2800mmio_interrupt(int irq
 115         mask = ~reg;
 116
 117         if (rt2x00_get_field32(reg, INT_SOURCE_CSR_TX_FIFO_STATUS)) {
 118 -               rt2800mmio_txstatus_interrupt(rt2x00dev);
 119 +               rt2800mmio_txstatus_interrupt(rt2x00dev, txstatus);
 120                 /*
 121                  * Never disable the TX_FIFO_STATUS interrupt.
 122                  */
 123 --- a/drivers/net/wireless/ralink/rt2x00/rt2x00.h
 124 +++ b/drivers/net/wireless/ralink/rt2x00/rt2x00.h
 125 @@ -991,6 +991,11 @@ struct rt2x00_dev {
 126         int rf_channel;
 127
 128         /*
 129 +        * Counter for tx status irq retries (rt2800pci).
 130 +        */
 131 +       unsigned int txstatus_irq_retries;
 132 +
 133 +       /*
 134          * Protect the interrupt mask register.
 135          */
 136         spinlock_t irqmask_lock;