Re: libata NCQ implementation questions

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Tejun Heo wrote:
Mikael Pettersson wrote:
Mark Lord writes:
 > Mikael Pettersson wrote:
 > > I've started working on NCQ support for sata_promise,
 > > and I have a few questions regarding NCQ and libata:
 > >  > > 1. Can I rely not seeing any non-NCQ commands while there
 > >    are uncompleted NCQ commands on a port?
 > ..
 >  > No, you cannot.  So you'll have to code a .qc_defer() method
 > to hold them off in that case.  For a *really* good example,
 > see my recently deployed mv_qc_defer() function in sata_mv.c
 > as of linux-2.6.26-rc2.

Hmm, so I misinterpreted ata_std_qc_defer()? Ok, I'll look
at sata_mv's version.

ata_std_qc_defer() which is inherited from sata_port_ops does guarantee that NCQ and non-NCQ commands don't mix on a single device. Mark, you're talking about PMP, right?
..

Ahh.. probably, yes.  I just saw it mixing PIO with NCQ and then
turfed it in favour of a more comprehensive mv_qc_defer().

But that was with a PM connected at the time, and I don't remember if
I also saw it without a PM.

Cheers
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