linux-kernel - Re: [PATCH v2 5/7] ASoC: qdsp6: Add depends on OF

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Date:   Tue, 19 Jun 2018 10:36:39 +0100
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     Rob Herring <robh+dt@...nel.org>,
        Niklas Cassel <niklas.cassel@...aro.org>
Cc:     Mark Brown <broonie@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Andy Gross <andy.gross@...aro.org>,
        Patrick Lai <plai@...eaurora.org>,
        Banajit Goswami <bgoswami@...eaurora.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Linux-ALSA <alsa-devel@...a-project.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 5/7] ASoC: qdsp6: Add depends on OF



On 18/06/18 21:53, Rob Herring wrote:
> On Mon, Jun 18, 2018 at 2:08 PM, Niklas Cassel <niklas.cassel@...aro.org> wrote:
>> On Mon, Jun 18, 2018 at 08:48:32AM -0600, Rob Herring wrote:
>>> On Mon, Jun 18, 2018 at 6:39 AM, Niklas Cassel <niklas.cassel@...aro.org> wrote:
>>>> On Mon, Jun 18, 2018 at 12:06:42PM +0100, Mark Brown wrote:
>>>>> On Thu, Jun 14, 2018 at 01:11:36PM +0200, Niklas Cassel wrote:
>>>>>> of_platform_device_destroy is only defined when building
>>>>>> with CONFIG_OF=y. Add a depends on OF.
>>>>>
>>>>> Is it sensible that of_platform_device_destroy() is only defined when
>>>>> building with CONFIG_OF=y?
>>>>
>>>> I'm redirecting that question to the device tree maintainers.
>>>>
>>>> There are a few of_* functions in include/linux/of_platform.h
>>>> that are only defined when CONFIG_OF=y:
>>>>
>>>> of_platform_device_create()
>>>> of_platform_device_destroy()
>>>> of_platform_bus_probe()
>>>> of_device_alloc()
>>>>
>>>> Rob, Frank, do you want me to create static inline dummy versions of these?
>>>
>>> No, because generally you should not be using these functions
>>> directly. Yes, there are some users, but if you look at the tree,
>>> there are few or isolated (PowerPC) users. Using
>>> of_platform_populate/of_platform_depopulate is preferred.
>>
>> of_platform_device_destroy() is also used by sound/soc/qcom/qdsp6/*
>> which is why I suggested this patch:
>> https://marc.info/?l=alsa-devel&m=152932497413567
>> that adds "depends on OF" for SND_SOC_QDSP6 in sound/soc/qcom/Kconfig.
>>
>> Or do you think that a better solution would be to modify
>> sound/soc/qcom/qdsp6/* so that it instead uses
>> of_platform_populate()/of_platform_depopulate()?
> 
> Yes, that is preferred. However, that won't work here because the
> child nodes don't have compatible strings. Maybe we should add them as
> this all just went in. That would also allow DT based module
> autoloading to work (which I don't think would currently). Really, as
> is, of_platform_device_create isn't needed here and you could just use
> platform_device_register_simple instead. The child driver would have
> to get the DT node pointer from the parent device instead.
> 
compatible was the reason why I started using 
of_platform_device_{create,destroy} apis. As you said we could also do 
it with simple platform device too.

I think adding compatible seems to be better option here along with 
of_platform_populate()/of_platform_depopulate(), I will try this!

thanks,
srini

> But if you want to add empty functions for just
> of_platform_device_{create,destroy}, I guess that is fine.
> 
> Rob
>