src/patches/suse-2.6.27.25/patches.drivers/libata-ata_piix-clear-spurious-IRQ

   1 From: Tejun Heo <tj@kernel.org>
   2 Subject: ata_piix: detect and clear spurious IRQs
   3 References: bnc#445872
   4
   5 The DMA_IRQ bit in the bmdma status register is always set when IDEIRQ
   6 is asserted allowing spurious IRQ detection.  Detect spurious IRQs and
   7 clear them.  This protects ata_piix against nobody-cared which gets
   8 reported not so rarely.
   9
  10 Signed-off-by: Tejun Heo <tj@kernel.org>
  11 Signed-off-by: Tejun Heo <teheo@suse.de>
  12 ---
  13  drivers/ata/ata_piix.c |   54 ++++++++++++++++++++++++++++++++++++++++++++++++-
  14  1 file changed, 53 insertions(+), 1 deletion(-)
  15
  16 --- a/drivers/ata/ata_piix.c
  17 +++ b/drivers/ata/ata_piix.c
  18 @@ -923,6 +923,58 @@ static int piix_sidpr_scr_read(struct at
  19         return 0;
  20  }
  21
  22 +static irqreturn_t piix_interrupt(int irq, void *dev_instance)
  23 +{
  24 +       struct ata_host *host = dev_instance;
  25 +       unsigned int i;
  26 +       unsigned int handled = 0;
  27 +       unsigned long flags;
  28 +
  29 +       spin_lock_irqsave(&host->lock, flags);
  30 +
  31 +       for (i = 0; i < host->n_ports; i++) {
  32 +               struct ata_port *ap = host->ports[i];
  33 +               struct ata_queued_cmd *qc;
  34 +               u8 host_stat;
  35 +
  36 +               if (ata_port_is_dummy(ap))
  37 +                       continue;
  38 +
  39 +               qc = ata_qc_from_tag(ap, ap->link.active_tag);
  40 +               if (qc && !(qc->tf.flags & ATA_TFLAG_POLLING)) {
  41 +                       handled |= ata_sff_host_intr(ap, qc);
  42 +                       continue;
  43 +               }
  44 +
  45 +               /*
  46 +                * Control reaches here if HSM is not expecting IRQ.
  47 +                * If the controller is actually asserting IRQ line,
  48 +                * this will lead to nobody cared.  Fortuantely,
  49 +                * DMA_INTR of PIIX is set whenever IDEIRQ is set so
  50 +                * it can be used to detect spurious IRQs.  As the
  51 +                * driver is not expecting IRQ at all, clearing IRQ
  52 +                * here won't lead to loss of IRQ event.
  53 +                */
  54 +               if (unlikely(!ap->ioaddr.bmdma_addr))
  55 +                       continue;
  56 +
  57 +               host_stat = ap->ops->bmdma_status(ap);
  58 +               if (!(host_stat & ATA_DMA_INTR))
  59 +                       continue;
  60 +
  61 +               if (printk_ratelimit())
  62 +                       ata_port_printk(ap, KERN_INFO,
  63 +                                       "clearing spurious IRQ\n");
  64 +               ap->ops->sff_check_status(ap);
  65 +               ap->ops->sff_irq_clear(ap);
  66 +               handled |= 1;
  67 +       }
  68 +
  69 +       spin_unlock_irqrestore(&host->lock, flags);
  70 +
  71 +       return IRQ_RETVAL(handled);
  72 +}
  73 +
  74  static int piix_sidpr_scr_write(struct ata_link *link,
  75                                 unsigned int reg, u32 val)
  76  {
  77 @@ -1543,7 +1595,7 @@ static int __devinit piix_init_one(struc
  78         }
  79
  80         pci_set_master(pdev);
  81 -       return ata_pci_sff_activate_host(host, ata_sff_interrupt, &piix_sht);
  82 +       return ata_pci_sff_activate_host(host, piix_interrupt, &piix_sht);
  83  }
  84
  85  static int __init piix_init(void)