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From: akepner@sgi.com
To: Grant Grundler <grundler@parisc-linux.org>
Cc: Tony Luck <tony.luck@intel.com>,
	Jesse Barnes <jbarnes@virtuousgeek.org>,
	Jes Sorensen <jes@sgi.com>,
	Randy Dunlap <randy.dunlap@oracle.com>,
	Roland Dreier <rdreier@cisco.com>,
	James Bottomley <James.Bottomley@HansenPartnership.com>,
	David Miller <davem@davemloft.net>,
	Muli Ben-Yehuda <muli@il.ibm.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/4] dma: document dma_{un}map_{single|sg}_attrs() interface
Date: Thu, 31 Jan 2008 19:07:51 -0800	[thread overview]
Message-ID: <20080201030751.GB28899@sgi.com> (raw)
In-Reply-To: <20080131223847.GA11872@colo.lackof.org>

On Thu, Jan 31, 2008 at 03:38:48PM -0700, Grant Grundler wrote:

Thanks for looking through this.

I'll send an updated patchset that addresses your comments 
as soon as I can - probably around Monday.

> ...
> > +struct dma_attrs encapsulates a set of "dma attributes". For the 
> > +definition of struct dma_attrs see linux/dma-attrs.h. 
> 
> Because all architectures will share the set of attrs definitions,
> would it be reasonable to document the intent of each attr?
> 
> Two reasons for doing this:
> 1) people reading the driver code should understand WHY the dma attr was added.
> 2) other arch maintainers need to know in order to implement the same attr
>    for their shiny new toys.
> 
> 
> > +The interpretation of dma attributes is architecture-specific. 
> 
> This statement is really important....but:
> Could we add a reference to arch documentation for each attr?
> 
> ie something public (doesn't have to be in linux source tree)
> which explains the subtlies of how that DMA attr actually works.
> 
> Having worked on HP chipsets for 10+ years, I know releasing
> original HW docs is often not possible. I'm not asking for the
> impossible. Please don't flame me for that. But if the company
> is willing to publish the existance of a feature, a paragraph or
> two would be good marketing too. Maybe just include comments in
> the arch/ code that implements the feature and reference those
> comments in DMA-API.txt.
> ....

OK, I can certainly add an explanation of the attribute that
I'm worried about. 

I think there's a reference to this behavior in our driver 
porting guide - I can add a pointer to that, too. 

This might also address your point above about documenting 
each attribute - let me know once the next patch is out.

-- 
Arthur


      reply	other threads:[~2008-02-01  3:09 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-30  5:50 akepner
2008-01-31 22:38 ` Grant Grundler
2008-02-01  3:07   ` akepner [this message]

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