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From: Tejun Heo <htejun@gmail.com>
To: Mikael Pettersson <mikpe@it.uu.se>
Cc: Mark Lord <liml@rtr.ca>, jgarzik@pobox.com, linux-ide@vger.kernel.org
Subject: Re: libata NCQ implementation questions
Date: Tue, 13 May 2008 17:32:15 +0900	[thread overview]
Message-ID: <4829520F.6020304@gmail.com> (raw)
In-Reply-To: <18472.38839.647001.510236@alkaid.it.uu.se>

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?

Thanks.

-- 
tejun

  reply	other threads:[~2008-05-13  8:32 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-05-11 23:19 libata NCQ implementation questions Mikael Pettersson
2008-05-12  4:05 ` Grant Grundler
2008-05-12 12:22   ` Mikael Pettersson
2008-05-12 15:58 ` Mark Lord
2008-05-12 19:17   ` Mikael Pettersson
2008-05-13  8:32     ` Tejun Heo [this message]
2008-05-13 21:01       ` Mark Lord
2008-05-13  8:40 ` Tejun Heo
2008-05-13  9:25   ` Mikael Pettersson

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