ide: clear bmdma status in ide_intr() for ICHx controllers (revised #4)

patch 1/2 (revised):
- Fix drive->waiting_for_dma to work with CDB-intr devices.
- Do the dma status clearing in ide_intr() and add a new
  hwif->ide_dma_clear_irq for Intel ICHx controllers.

Revised per Alan, Sergei and Bart's advice.

Patch against 2.6.20-rc6. Tested ok on my ICH4 and pdc20275 adapters.
Please review/apply, thanks.

Signed-off-by: Albert Lee <albertcc@tw.ibm.com>
Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: "Adam W. Hawks" <awhawks@us.ibm.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

4 files changed, 68 insertions, 15 deletions

diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c
index 5969cec58dc1..21f4ae2b7176 100644
--- a/drivers/ide/ide-cd.c
+++ b/drivers/ide/ide-cd.c
@@ -930,6 +930,10 @@ static ide_startstop_t cdrom_start_packet_command(ide_drive_t *drive,
                 HWIF(drive)->OUTB(drive->ctl, IDE_CONTROL_REG);
  
         if (CDROM_CONFIG_FLAGS (drive)->drq_interrupt) {
+                /* waiting for CDB interrupt, not DMA yet. */
+                if (info->dma)
+                        drive->waiting_for_dma = 0;
+
                 /* packet command */
                 ide_execute_command(drive, WIN_PACKETCMD, handler, ATAPI_WAIT_PC, cdrom_timer_expiry);
                 return ide_started;
@@ -972,6 +976,10 @@ static ide_startstop_t cdrom_transfer_packet_command (ide_drive_t *drive,
                 /* Check for errors. */
                 if (cdrom_decode_status(drive, DRQ_STAT, NULL))
                         return ide_stopped;
+
+                /* Ok, next interrupt will be DMA interrupt. */
+                if (info->dma)
+                        drive->waiting_for_dma = 1;
         } else {
                 /* Otherwise, we must wait for DRQ to get set. */
                 if (ide_wait_stat(&startstop, drive, DRQ_STAT,
diff --git a/drivers/ide/ide-io.c b/drivers/ide/ide-io.c
index 2614f41b5074..99d1c43f433e 100644
--- a/drivers/ide/ide-io.c
+++ b/drivers/ide/ide-io.c
@@ -1646,6 +1646,17 @@ irqreturn_t ide_intr (int irq, void *dev_id)
         del_timer(&hwgroup->timer);
         spin_unlock(&ide_lock);
 
+        /* Some controllers might set DMA INTR no matter DMA or PIO;
+         * bmdma status might need to be cleared even for
+         * PIO interrupts to prevent spurious/lost irq.
+         */
+        if (hwif->ide_dma_clear_irq && !(drive->waiting_for_dma))
+                /* ide_dma_end() needs bmdma status for error checking.
+                 * So, skip clearing bmdma status here and leave it
+                 * to ide_dma_end() if this is dma interrupt.
+                 */
+                hwif->ide_dma_clear_irq(drive);
+
         if (drive->unmask)
                 local_irq_enable_in_hardirq();
         /* service this interrupt, may set handler for next interrupt */
diff --git a/drivers/ide/ide.c b/drivers/ide/ide.c
index c750f6ce770a..65eb095469b5 100644
--- a/drivers/ide/ide.c
+++ b/drivers/ide/ide.c
@@ -509,6 +509,7 @@ static void ide_hwif_restore(ide_hwif_t *hwif, ide_hwif_t *tmp_hwif)
         hwif->ide_dma_on                = tmp_hwif->ide_dma_on;
         hwif->ide_dma_off_quietly       = tmp_hwif->ide_dma_off_quietly;
         hwif->ide_dma_test_irq          = tmp_hwif->ide_dma_test_irq;
+        hwif->ide_dma_clear_irq         = tmp_hwif->ide_dma_clear_irq;
         hwif->ide_dma_host_on           = tmp_hwif->ide_dma_host_on;
         hwif->ide_dma_host_off          = tmp_hwif->ide_dma_host_off;
         hwif->ide_dma_lostirq           = tmp_hwif->ide_dma_lostirq;
diff --git a/drivers/ide/pci/piix.c b/drivers/ide/pci/piix.c
index 52cfc2ac22c1..af65b0888bbb 100644
--- a/drivers/ide/pci/piix.c
+++ b/drivers/ide/pci/piix.c
@@ -410,17 +410,14 @@ fast_ata_pio:
 }
 
 /**
- *      init_chipset_piix       -       set up the PIIX chipset
- *      @dev: PCI device to set up
- *      @name: Name of the device
+ *      piix_is_ichx    -       check if ICHx
+ *      @dev: PCI device to check
  *
- *      Initialize the PCI device as required. For the PIIX this turns
- *      out to be nice and simple
+ *      returns 1 if ICHx, 0 otherwise.
  */
- 
-static unsigned int __devinit init_chipset_piix (struct pci_dev *dev, const char *name)
+static int piix_is_ichx(struct pci_dev *dev)
 {
-        switch(dev->device) {
+        switch (dev->device) {
                 case PCI_DEVICE_ID_INTEL_82801EB_1:
                 case PCI_DEVICE_ID_INTEL_82801AA_1:
                 case PCI_DEVICE_ID_INTEL_82801AB_1:
@@ -438,19 +435,51 @@ static unsigned int __devinit init_chipset_piix (struct pci_dev *dev, const char
                 case PCI_DEVICE_ID_INTEL_ICH7_21:
                 case PCI_DEVICE_ID_INTEL_ESB2_18:
                 case PCI_DEVICE_ID_INTEL_ICH8_6:
-                {
-                        unsigned int extra = 0;
-                        pci_read_config_dword(dev, 0x54, &extra);
-                        pci_write_config_dword(dev, 0x54, extra|0x400);
-                }
-                default:
-                        break;
+                        return 1;
         }
 
         return 0;
 }
 
 /**
+ *      init_chipset_piix       -       set up the PIIX chipset
+ *      @dev: PCI device to set up
+ *      @name: Name of the device
+ *
+ *      Initialize the PCI device as required. For the PIIX this turns
+ *      out to be nice and simple
+ */
+
+static unsigned int __devinit init_chipset_piix (struct pci_dev *dev, const char *name)
+{
+        if (piix_is_ichx(dev)) {
+                unsigned int extra = 0;
+                pci_read_config_dword(dev, 0x54, &extra);
+                pci_write_config_dword(dev, 0x54, extra|0x400);
+        }
+
+        return 0;
+}
+
+/**
+ *      piix_dma_clear_irq      -       clear BMDMA status
+ *      @drive: IDE drive to clear
+ *
+ *      Called from ide_intr() for PIO interrupts
+ *      to clear BMDMA status as needed by ICHx
+ */
+static void piix_dma_clear_irq(ide_drive_t *drive)
+{
+        ide_hwif_t *hwif = HWIF(drive);
+        u8 dma_stat;
+
+        /* clear the INTR & ERROR bits */
+        dma_stat = hwif->INB(hwif->dma_status);
+        /* Should we force the bit as well ? */
+        hwif->OUTB(dma_stat, hwif->dma_status);
+}
+
+/**
  *      init_hwif_piix          -       fill in the hwif for the PIIX
  *      @hwif: IDE interface
  *
@@ -486,6 +515,10 @@ static void __devinit init_hwif_piix(ide_hwif_t *hwif)
         if (!hwif->dma_base)
                 return;
 
+        /* ICHx need to clear the bmdma status for all interrupts */
+        if (piix_is_ichx(hwif->pci_dev))
+                hwif->ide_dma_clear_irq = &piix_dma_clear_irq;
+
         hwif->atapi_dma = 1;
         hwif->ultra_mask = 0x3f;
         hwif->mwdma_mask = 0x06;