Subject: Re: IDE driver in polling mode

From: Mark Lord <[email-masked]>
Date: Thu, 12 Apr 2007 09:39:03 -0400

Michael,

Here is a patch to have drivers/ide use polling
for all operations, in addition to IRQs.

Patch is against 2.6.21, but should apply and work equally well
on earlier kernels (including 2.6.14).

This quick hack is *not* for general kernel inclusion.
It works for me.  I tested it using a CF card in a PC-CARD adapter.

Signed-off-by:  Mark Lord <[email-masked]>

--- 2.6.21/drivers/ide/ide-probe.c	2007-04-11 00:18:51.000000000 -0400
+++ new/drivers/ide/ide-probe.c	2007-04-12 09:26:14.000000000 -0400
@@ -1014,6 +1014,27 @@
  * but anything else has led to problems on some machines.  We re-enable
  * interrupts as much as we can safely do in most places.
  */
+struct timer_list polling_timer;
+static void ide_polling (unsigned long data)
+{
+	ide_hwgroup_t *hwgroup = (void *)data;
+	ide_hwif_t *hwif;
+	int irq = 0;
+
+	if (hwgroup) {
+		hwif = hwgroup->hwif;
+		if (hwif)
+			irq = hwif->irq;
+	}
+
+	ide_intr(irq, hwgroup);
+	init_timer(&polling_timer);
+	polling_timer.expires = jiffies + 1;
+	polling_timer.function = &ide_polling;
+	polling_timer.data = (unsigned long) hwgroup;
+	add_timer(&polling_timer);
+}
+
 static int init_irq (ide_hwif_t *hwif)
 {
 	unsigned int index;
@@ -1110,9 +1131,12 @@
 		if (hwif->io_ports[IDE_CONTROL_OFFSET])
 			/* clear nIEN */
 			hwif->OUTB(0x08, hwif->io_ports[IDE_CONTROL_OFFSET]);
-
+#if 0
 		if (request_irq(hwif->irq,&ide_intr,sa,hwif->name,hwgroup))
 	       		goto out_unlink;
+#else
+		ide_polling((unsigned long)hwgroup);
+#endif
 	}
 
 	/*
@@ -1156,6 +1180,7 @@
 	printk("\n");
 	up(&ide_cfg_sem);
 	return 0;
+#if 0
 out_unlink:
 	spin_lock_irq(&ide_lock);
 	if (hwif->next == hwif) {
@@ -1176,6 +1201,7 @@
 		BUG_ON(hwgroup->hwif == hwif);
 	}
 	spin_unlock_irq(&ide_lock);
+#endif
 out_up:
 	up(&ide_cfg_sem);
 	return 1;
--- 2.6.21/drivers/ide/ide.c	2007-04-11 00:18:51.000000000 -0400
+++ new/drivers/ide/ide.c	2007-04-12 09:31:59.000000000 -0400
@@ -569,6 +569,8 @@
  *	This is raving bonkers.
  */
 
+extern struct timer_list polling_timer;
+
 void ide_unregister(unsigned int index)
 {
 	ide_drive_t *drive;
@@ -612,7 +614,11 @@
 		g = g->next;
 	} while (g != hwgroup->hwif);
 	if (irq_count == 1)
+#if 0
 		free_irq(hwif->irq, hwgroup);
+#else
+		del_timer(&polling_timer);
+#endif
 
 	spin_lock_irq(&ide_lock);
 	/*