Re: libata oops 2.6.11-rc4 yesterdays BK

[Andy Warner <andyw@pobox.com>]

Jeff Garzik wrote:
> [...]
> AHCI is the first scenario where PIO-via-DMA could be utilized in an 
> efficient manner.  The upcoming SiI 3124 is another.  A few others 
> (ADMA, Marvell) are PIO-via-DMA controllers as well.  I agree this is a 
> good thing.

I _think_ the SATA-II stuff from Promise (20579) does this too.

> Anyway, getting back to the thread of "problems with PIO polling", I am 
> wondering if -- due to SATA's nature -- PIO polling should be avoided, 
> and interrupt-driven methodology used instead.
> 
> One reason why PIO polling was chosen (for controllers that support it; 
> AHCI does not) is that the entire command submission/processing code can 
> be written inline:  just submit-command, wait-for-busy-clear, etc. 
> Makes the code less complex.

I think going interrupt driven would be a good idea. Of course
when I tried it one chip didn't serve up the interrupt as expected
(can't remember is it was the 3114 or the 20319 - would have to
check my notes.) I don't think it is massively more complex than
what we currently have, and quite possibly might be simpler.
-- 
andyw@pobox.com

Andy Warner		Voice: (612) 801-8549	Fax: (208) 575-5634