linux-kernel - Re: [PATCH v2 5/7] staging: board: Add support for devices with complex dependencies

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Date:	Fri, 4 Sep 2015 10:30:34 +0200
From:	Ulf Hansson <ulf.hansson@...aro.org>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:	Geert Uytterhoeven <geert+renesas@...der.be>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Simon Horman <horms+renesas@...ge.net.au>,
	Magnus Damm <damm+renesas@...nsource.se>,
	Arnd Bergmann <arnd@...db.de>,
	Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
	Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>,
	Marc Zyngier <marc.zyngier@....com>,
	driverdevel <devel@...verdev.osuosl.org>,
	Linux-sh list <linux-sh@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 5/7] staging: board: Add support for devices with
 complex dependencies

On 3 September 2015 at 15:35, Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> Hi Ulf,
>
> On Thu, Sep 3, 2015 at 2:53 PM, Ulf Hansson <ulf.hansson@...aro.org> wrote:
>> On 17 June 2015 at 10:38, Geert Uytterhoeven <geert+renesas@...der.be> wrote:
>>> Add support for easy registering of one ore more platform devices that
>>> may:
>>>   - need clocks that are described in DT,
>>>   - be part of a PM Domain.
>
>>> diff --git a/drivers/staging/board/board.c b/drivers/staging/board/board.c
>>> index 8712f566b31196e0..29d456e29f38feac 100644
>>> --- a/drivers/staging/board/board.c
>>> +++ b/drivers/staging/board/board.c
>
>>> +int __init board_staging_register_device(const struct board_staging_dev *dev)
>>> +{
>>> +       struct platform_device *pdev = dev->pdev;
>>> +       unsigned int i;
>>> +       int error;
>>> +
>>> +       pr_debug("Trying to register device %s\n", pdev->name);
>>> +       if (board_staging_dt_node_available(pdev->resource,
>>> +                                           pdev->num_resources)) {
>>> +               pr_warn("Skipping %s, already in DT\n", pdev->name);
>>> +               return -EEXIST;
>>> +       }
>>> +
>>> +       board_staging_gic_fixup_resources(pdev->resource, pdev->num_resources);
>>> +
>>> +       for (i = 0; i < dev->nclocks; i++)
>>> +               board_staging_register_clock(&dev->clocks[i]);
>>> +
>>> +       error = platform_device_register(pdev);
>>> +       if (error) {
>>> +               pr_err("Failed to register device %s (%d)\n", pdev->name,
>>> +                      error);
>>> +               return error;
>>> +       }
>>> +
>>> +       if (dev->domain)
>>> +               __pm_genpd_name_add_device(dev->domain, &pdev->dev, NULL);
>>
>> Urgh, this managed to slip through my filters.
>>
>> It seems like we almost managed to remove all users of the
>> "..._name_add..." APIs for genpd. If hasn't been for $subject patch.
>> :-)
>>
>> Now, I realize this is already too late here, but let's try to fix
>> this before it turns into a bigger issue.
>>
>> Geert, do you think it's possible to convert into using the non-named
>> bases APIs?
>
> That will be difficult. This code is meant to use drivers that are not yet
> DT-aware on DT-based systems. Hence it uses platform devices with named PM
> domains, while the PM domains are described in DT.
> I don't think there's another way to look up a PM domain by name, is there?

As a matter of fact there are, especially for those genpds that has
been created through DT as in this case. The API to use is
of_genpd_get_from_provider() to find the struct generic_pm_domain.

Yes, I do realize that you need to manage the parsing of the domain
name to make sure it's the one you want, but I would rather keep that
"hack" in this driver than in the generic API.

>
> This code is meant to go away, once all drivers are converted to DT, or
> considered obsolete.

Well, who knows *when* that is going to happen. :-)

Kind regards
Uffe
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