linux-kernel - Re: [PATCH] of: reduce the number of PROBE

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Date:	Thu, 22 Aug 2013 10:00:08 +0200
From:	Jean-Francois Moine <moinejf@...e.fr>
To:	Grant Likely <grant.likely@...aro.org>
Cc:	Rob Herring <rob.herring@...xeda.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] of: reduce the number of PROBE_DEFERs

On Tue, 20 Aug 2013 11:13:24 +0100
Grant Likely <grant.likely@...aro.org> wrote:

> On Tue, Aug 20, 2013 at 11:01 AM, Jean-Francois Moine <moinejf@...e.fr> wrote:
> > This patch populates the platform from the device tree into two steps:
> > the first step creates the nodes that are referenced by a phandle,
> > the second step creates the other nodes.
> >
> > This permits to reduce the number of PROBE_DEFERs.
> >
> > Signed-off-by: Jean-Francois Moine <moinejf@...e.fr>
> > ---
> > A better way to reduce probe deferral could be sorting the nodes
> > according to their phandle level in the DT blob at compilation time ...  
> 
> Have you got measurements or statistics that show this making a
> difference? I suspect you'll find for boot time it will have little to
> no affect since the device driver probe order is more closely related
> to the kernel link order than the order that devices were registered.

With the device tree and most drivers as modules, the kernel link order
does not matter.

I admit that the gain may be small: I just get none or just one probe
deferral instead of 3 on my cubox with this patch.

-- 
Ken ar c'hentañ	|	      ** Breizh ha Linux atav! **
Jef		|		http://moinejf.free.fr/
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