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>

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,

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 */

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;

drivers/ide/pci/piix.c

@@ -410,17 +410,14 @@ static int piix_config_drive_xfer_rate (ide_drive_t *drive)
 }
 
 /**
- *	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:
@@ -438,18 +435,50 @@ 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:
-		{
+			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);
 	}
-		default:
-			break;
-	}
 
 	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;

include/linux/ide.h

@@ -738,6 +738,7 @@ typedef struct hwif_s {
 	int (*ide_dma_on)(ide_drive_t *drive);
 	int (*ide_dma_off_quietly)(ide_drive_t *drive);
 	int (*ide_dma_test_irq)(ide_drive_t *drive);
+	void (*ide_dma_clear_irq)(ide_drive_t *drive);
 	int (*ide_dma_host_on)(ide_drive_t *drive);
 	int (*ide_dma_host_off)(ide_drive_t *drive);
 	int (*ide_dma_lostirq)(ide_drive_t *drive);