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SubjectRe: BUG: 2.4.18 & ALI15X3 DMA hang on boot
Jeff Garzik wrote:
> Martin Dalecki wrote:
>> John Langford wrote:
>>> I went nuts with printk statements and managed to isolate the hang to
>>> one particular line of code. The final printk in this code fragment
>>> never gets executed. } else if (m5229_revision >=
>>> 0xC3) {
>>> /*
>>> * 1553/1535 (m1533, 0x79, bit 1)
>>> */
>>> printk("ata66_ali15x3 } else if
>>> (m5229_revisi\on >= 0xC3) {\n");
>>> pci_write_config_byte(isa_dev, 0x79, tmpbyte
>>> | 0x02);
>> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>> pci_write_config to isa_dev???? This looks at least suspicious.
>> You may very well check whatever isa_dev is trully a PCI device
>> handle or just some random IO base for ISA bus!
> Nope, look at the code and comments around "isa_dev" :)

OK OK - this was just a blind guess without looking at the actual
code :-).

> isa_dev is the PCI device structure for the ALi ISA bridge... very
> definitely a PCI device.

Sure i know.

> some background:
> It is normal in some situations that you need to examine or set PCI
> config registers for the ISA bridge, when dealing with some IDE
> motherboards. The southbridge is typically the chip that actually
> implements IDE on your motherboard. Even though IDE is normally
> exported as a separate PCI device, you still have to deal with the ATA
> register blocks at hardcoded legacy ISA addresses 0x1f0 and 0x170. So,
> when you write the ATA registers for channel 0 or channel 1, you are
> writing to 0x1f? or 0x17?, the ISA bridge is most likely the portion of
> the southbridge chip actually decoding those addresses for you.

Thank you for elaborating on this, but I did already know this...

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