[PATCH] of: reduce the number of PROBE_DEFERs

[Grant Likely]

On Thu, Aug 22, 2013 at 9:00 AM, Jean-Francois Moine <moinejf at free.fr> wrote:
> On Tue, 20 Aug 2013 11:13:24 +0100
> Grant Likely <grant.likely at linaro.org> wrote:
>
>> On Tue, Aug 20, 2013 at 11:01 AM, Jean-Francois Moine <moinejf at free.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 at free.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.

If you've only got 3 probe deferrals, then is this really an issue
worth complicating the code over? I'd like to see a more significant
impact before taking this step.

g.