[PATCH] OF device tree update (2.5)

Hollis Blanchard hollisb at us.ibm.com
Tue Oct 14 22:41:06 EST 2003

On Tuesday, Oct 14, 2003, at 01:35 US/Central, Paul Mackerras wrote:
>> The device tree and global list are protected by a read-write
>> spinlock.
>>       The device_node structure has gained a reference count, a flags
>> field, and a few fields for keeping track of procfs entries.  There is
>> no per-node lock at this time.
> This part sounds OK.  Does anything in the ppc64 world use the addrs,
> n_addrs, intrs or n_intrs fields of the device node?  Maybe you can
> leave out the initialization of those fields when you add a node.
> (Ben H has suggested getting rid of them.)

It's funny, I was just stepping through code that does yesterday with
Linda. pci_read_irq_line() (in pSeries_pci.c) overwrites the PCI
device's PCI_INTERRUPT_LINE config byte with OF_node->intrs[0].

A related question: how can we have interrupt lines like 0x146 when the
line value is just a byte? Is that the point of this code -- OF knows
the real value, but the field in PCI config space is too small?

Hollis Blanchard
IBM Linux Technology Center

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