linux-kernel - Re: [RFC PATCH] regulator: introduce boot protection flag

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Date:	Thu, 23 Jun 2016 20:02:01 +0800
From:	Pingbo Wen <pingbo.wen@...aro.org>
To:	Mark Brown <broonie@...nel.org>
Cc:	pingbo.wen@...aro.org, linux-kernel@...r.kernel.org,
	lgirdwood@...il.com, vincent.guittot@...aro.org,
	stephen.boyd@...aro.org
Subject: Re: [RFC PATCH] regulator: introduce boot protection flag

Hi, Mark

On Friday, June 17, 2016 07:42 PM, Mark Brown wrote:
> On Fri, Jun 17, 2016 at 11:34:25AM +0800, Pingbo Wen wrote:
>> On Wednesday, June 15, 2016 09:32 PM, Mark Brown wrote:
> 
>>> Having the consumer driver know that it's "critical" seems wrong since
>>> different systems may have different ideas about that, it's probably
>>> better to hook this in with the device model so that when the device
>>> finishes probing that kicks things off.
> 
>> That will imply the protection would be end when the specific device has
>> probed, and consumers should take their place at the same time. But
>> there have some other devices, which will set the consumer in a IRQ
>> event, or after some other events, can't be covered.
> 
> I don't understand what this means, sorry.
> 

I mean maybe there's some consumer driver only do partial initialization
during probing.

>> We can set the protection flag easily, but it's hard to tell whether a
>> consumer is well initialized, the end of protection, since regulator
>> consumer is not initialized within one call.
> 
> If the driver is not initializing itself during probe the driver is
> doing something wrong and needs to be fixed anyway.
> 

OK, if all driver have full initialized during probing, and we need
insert a hook after driver probing. I think we can add a function in
driver/base/dd.c:driver_probe_device() as this:

	ret = really_probe(dev, drv);
	...
	if (!ret)
		regulator_clean_up(dev);

And in regulator_clean_up(), we can iterate all regulator deivce, and
call a regulator_clear_boot_protection function:

	if (!rdev->constraints->boot_protection)
		return 0;

	if (strcmp(rdev->constraints->critical_consumer, dev_name(dev)))
		return 0;

	rdev->constraints->boot_protection = 0;
	...
	-real clean stuffs-

the critical_consumer can be specified in devicetree.

Add a callback in driver_probe_device() is not so good, but it's fine
for me.

Pingbo