linux-kernel - Re: [PATCH v2 all 00/14] use of_platform_default

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Date:	Thu, 21 Apr 2016 15:55:54 +0800
From:	Kefeng Wang <wangkefeng.wang@...wei.com>
To:	Rob Herring <robh+dt@...nel.org>
CC:	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Arnd Bergmann <arnd@...db.de>, Shawn Guo <shawnguo@...nel.org>,
	Catalin Marinas <catalin.marinas@....com>,
	"Russell King - ARM Linux" <linux@....linux.org.uk>,
	Grant Likely <grant.likely@...aro.org>,
	Olof Johansson <olof@...om.net>,
	Masahiro Yamada <yamada.masahiro@...ionext.com>,
	Hanjun Guo <guohanjun@...wei.com>
Subject: Re: [PATCH v2 all 00/14] use of_platform_default_populate() to
 populate default bus

Hi Rob,

On 2016/4/20 5:10, Rob Herring wrote:
> On Wed, Mar 16, 2016 at 2:35 AM, Kefeng Wang <wangkefeng.wang@...wei.com> wrote:
>> Use helper of_platform_default_populate() in linux/of_platform
>> when possible, instead of calling of_platform_populate() with
>> the default match table.
>>
>> Then it is possible for driver code build as a module, and no
>> need to export of_default_bus_match_table anymore.
>>
>> This patchset is based on Linux 4.5.
>>
>> Changes since v1:
>> - Add ack, test and review
>> - Remove v1 patch 14/15, the similar patch has posted and applied,
>>   see https://patchwork.kernel.org/patch/8096991/
>>
>> v1:
>> - https://lkml.org/lkml/2016/1/26/1123
> 
> I was going to apply this, but I've thought about this some more and
> it is a lot of tree wide churn for little gain. Most of the call sites
> here I want to get rid of by making of_platform_populate callable
> multiple times. The infrastructure is almost there, but I think we
> just need something like this:
> 
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index 8d103e4..b25e710 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -345,6 +345,9 @@ static int of_platform_bus_create(struct device_node *bus,
>                 return 0;
>         }
> 
> +       if (of_node_check_flag(bus, OF_POPULATED_BUS))
> +               return 0;
> +
>         auxdata = of_dev_lookup(lookup, bus);
>         if (auxdata) {
>                 bus_id = auxdata->name;
> 
> Then we can call of_platform_populate from the DT core and remove all
> the default calls.

OK, it seems that we can drop all the of_of_platform_default_populate in arch code
by this changes, will do it.

But replace of_platform_populate() with the default match table by of_platform_default_populate
is a cleanup, and especially for the driver, we can not need export of_default_bus_match_table
after that.

There is a v3 patchset[1], it is based 4.6-rc2 with some updated, should this be merge firstly,
then drop all the default of_platform_populate in arch code, and I think the of_iommu_init() in
arch code could do the same thing.

If not, I will repost the patches with new ways, but still exists the part of unexport
of_default_bus_match_table by helper of_platform_default_populate().

Hope the v3 patchset could be merge in advance, after all, it has been reviewed fully. Thanks a lot.

BRs,
Kefeng


[1] https://lkml.org/lkml/2016/4/5/55

> 
> Rob
> 
> .
>