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

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Message-ID: <CAL_Jsq+cGbrtz6ZC8fgdD3H1yk7rWpzc9rg8uXOXqL6EJJDsOg@mail.gmail.com>
Date:	Thu, 21 Apr 2016 08:10:48 -0500
From:	Rob Herring <robh+dt@...nel.org>
To:	Kefeng Wang <wangkefeng.wang@...wei.com>
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

On Thu, Apr 21, 2016 at 2:55 AM, Kefeng Wang <wangkefeng.wang@...wei.com> wrote:
> 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.

We'd be touching the same line twice in a bunch of places if we apply
this series first, so it makes more sense to remove all these calls
first and then use of_platform_default_populate where it is still
needed.

Rob