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SubjectRe: linux-2.6.23 - acting funny
Date
Hi!

I had similar behavior in the kernel releases since I can think of.
(You may find some reports about at
http://marc.info/?a=113508574400006&r=1&w=2)

Maybe your problem is similar.

Here's what have been found out:
Plugin of ehci devices causes some strange DMA thing
which causes delays because of the CPU HLT instruction.
(DMA are handled with delays on HLT)

Possible fixes:
1) Kernel parameter: idle=poll
Disables HLT and causes heat up and noise from the cpu

2) Don't insert EHCI-USB devices

3) Patch: attached, try out at your own risk.
you need to add a kernel-boot parameter "disableviahlt"
(You've got a via-chipset, right?)

Please report back to me if 1/2 works or to linux-ide if the patch works.
Thanks

Helmut
--- kernel/drivers/ide/ide-dma.c 2006-08-20 11:31:53.000000000 +0200
+++ kernel/drivers/ide/ide-dma.c 2006-08-20 11:40:43.000000000 +0200
@@ -89,6 +89,57 @@
#include <asm/io.h>
#include <asm/irq.h>

+
+/* Some VIA boards show strange slowdown when HLT is eanbled */
+/* So we disable the HLT during a IDE-DMA transfer. */
+/* You need to pass disableviahlt at boottime to enable this */
+/* workaround. */
+#if defined(HAVE_DISABLE_HLT)
+
+static DEFINE_SPINLOCK(ide_hlt_lock);
+static int hlt_disabled;
+static int disableviahlt;
+static void ide_disable_hlt(void)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&ide_hlt_lock, flags);
+ if(disableviahlt) {
+ hlt_disabled++ ;
+ disable_hlt();
+ }
+ spin_unlock_irqrestore(&ide_hlt_lock, flags);
+}
+
+static void ide_enable_hlt(void)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&ide_hlt_lock, flags);
+ if(hlt_disabled && disableviahlt){
+ hlt_disabled--;
+ enable_hlt();
+ }
+ spin_unlock_irqrestore(&ide_hlt_lock, flags);
+}
+
+static int __init disable_via_hlt(char *str)
+{
+ printk(KERN_WARNING "DISABLE VIA HLT activated\n");
+ disableviahlt = 1;
+ return 1;
+}
+
+__setup("disableviahlt", disable_via_hlt);
+
+
+#else /* HAVE_DISABLE_HLT */
+inline static void ide_disable_hlt(void)
+{}
+inline static void ide_enable_hlt(void)
+{}
+#endif /* HAVE_DISABLE_HLT */
+
static const struct drive_list_entry drive_whitelist [] = {

{ "Micropolis 2112A" , "ALL" },
@@ -301,6 +352,7 @@
if (count) {
if (!is_trm290)
*--table |= cpu_to_le32(0x80000000);
+ ide_disable_hlt();
return count;
}
printk(KERN_ERR "%s: empty DMA table?\n", drive->name);
@@ -332,6 +384,7 @@
int nents = HWIF(drive)->sg_nents;

pci_unmap_sg(dev, sg, nents, HWIF(drive)->sg_dma_direction);
+ ide_enable_hlt();
}

EXPORT_SYMBOL_GPL(ide_destroy_dmatable);
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