Messages in this thread | | | Date | Tue, 23 Dec 2008 13:40:28 +0900 | From | Tejun Heo <> | Subject | Re: [PATCH] sata_sil: add Large Block Transfer support |
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Hello, Robert.
Robert Hancock wrote: > Tejun Heo wrote: >> >> ioread/iowrite? > > We know the register's always MMIO on this controller, so it's slightly > more optimal to avoid the conditional in there.
Yeah, by a small margin but I think the consensus was to use ioread/write no matter what if it's mapped using iomap. I don't think we guarantee iomapped address == mmio address after all.
>> I know it's not specific to this change but does mb() really make >> sense here? I don't think we need any barrier here. > > Not sure. Documentation/memory-barriers.txt seems rather unfortunately > vague on whether MMIO writes are strongly ordered with respect to memory > writes. I seem to recall some debate on this a while ago, did it ever > get resolved?
I remember that thread too but don't really any definite conclusion. Eh... I hate barriers lying around without exact explanation. :-(
Thanks.
-- tejun
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