Hi,
Panagiotis Issaris <panagiotis <at> gmail.com> writes:
> When booting Linux 2.6.19-rc3 (or 2.6.8-16sarge5 so it is not specific
> to the current kernels) on a friends laptop, I'm getting a lot of
> errormessages from the IDE controller related to DMA problems. When
> disabling all DMA related options, the kernel boots fine (and fast).
> With DMA enabled, it takes about 1 minute to stumble over the DMA
> problems. The laptop is Dell Latitude XPi CD P150ST.
Debian developer Frederik Schueler noted that as far as he knows the laptop does
not support DMA.
It seems that in drivers/ide/setup-pci.c, DMA is being forced on:
177 static unsigned long ide_get_or_set_dma_base (ide_hwif_t *hwif)
...
225 switch(dev->device) {
...
22x case PCI_DEVICE_ID_CMD_643:
...
234 if (simplex_stat & 0x80) {
235 printk(KERN_INFO "%s: simplex device: "
236 "DMA forced\n",
...
240 default:
241 /*
242 * If the device claims "simplex" DMA,
243 * this means only one of the two interfaces
244 * can be trusted with DMA at any point in time.
245 * So we should enable DMA only on one of the
246 * two interfaces.
247 */
...
259 printk(KERN_INFO "%s: simplex device: "
260 "DMA disabled\n",
...
I would guess it would be enough to remove the PCI_DEVICE_ID_CMD_643 and let it
be handled by the default case, thus disabling DMA. I will try the attached
patch on my friends laptop as soon as he brings it along.
With friendly regards,
Takis
diff --git a/drivers/ide/setup-pci.c b/drivers/ide/setup-pci.c
index 0719b64..5a7b6f6 100644
--- a/drivers/ide/setup-pci.c
+++ b/drivers/ide/setup-pci.c
@@ -226,7 +226,6 @@ #endif /* CONFIG_BLK_DEV_IDEDMA_FORCED *
case PCI_DEVICE_ID_AL_M5219:
case PCI_DEVICE_ID_AL_M5229:
case PCI_DEVICE_ID_AMD_VIPER_7409:
- case PCI_DEVICE_ID_CMD_643:
case PCI_DEVICE_ID_SERVERWORKS_CSB5IDE:
case PCI_DEVICE_ID_REVOLUTION:
simplex_stat = hwif->INB(dma_base + 2);
-
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