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SubjectRe: [patch 15/15] PNP: convert resource options to single linked list
On 04-06-08 01:03, Bjorn Helgaas wrote:

> That's definitely backwards. I reversed the sizes, so we'll have
> 8 bits for the priority byte (including compatibility/performance/
> robustness) and 16 bits for the dependent set number. Actually,
> I made the priority field 12 bits so we'd have space to keep
> PNP_RES_PRIORITY_INVALID as a truly out-of-band value.

Sounds perfect.

>>> + for (i = 0; i == 0 || i < dev->num_dependent_sets; i++) {
>>> + ret = pnp_assign_resources(dev, i);
>>> + if (ret == 0)
>>> return 0;
>> Eeeew. Perhaps:
>>
>> i = 0;
>> do {
>> ret = pnp_assign_resources(dev, i);
>> if (ret == 0)
>> return 0;
>> } while (++i < dev->num_dependent_sets);
>
> Heh :-) I vacillated on that one because I have a personal aversion
> to "do { ... } while ()", especially with a pre-increment. How would
> you feel about this alternative?
>
> ret = pnp_assign_resources(dev, 0);
> if (ret == 0)
> return 0;
>
> for (i = 1; i < dev->num_dependent_sets; i++) {
> ret = pnp_assign_resources(dev, i);
> if (ret == 0)
> return 0;
> }

You could fix the pre-increment by sticking a i++ inside the loop body
but there's no arguing with personal aversions...

Yes, I think the latter is better. Straight-forward and clear.

>> Why do you do 0x800, 0x400 in that order? Shouldn't it just be 0x400,
>> 0x800 to mimick the old order?
>
> I think they do end up in the correct order because I'm passing the
> same list_head to both list_add() calls, e.g., we'll have something
> like this:
>
> io -> ...
> io -> (io + 0x800) -> ...
> io -> (io + 0x400) -> (io + 0x800) -> ...

Yep. Just needed to see it happen once in the quirk testing I just now did.

> I need to go back over all your comments and make sure I've addressed
> them all, then I'll post the revised patches, hopefully tomorrow.
>
> Thanks again for all your work reviewing and testing these. It's
> been incredibly useful.

I've been impressed by this work. This is a good redesign of PnP with a
fully bisectable way to get there. And PnP was in need of some work...

Rene.


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