linux-kernel - Re: [PATCH V4 2/2] regulator: mt6323: Add support for MT6323 regulator

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Date:	Wed, 27 Jan 2016 14:41:05 +0000
From:	Mark Brown <broonie@...nel.org>
To:	John Crispin <blogic@...nwrt.org>
Cc:	Liam Girdwood <lgirdwood@...il.com>,
	Chen Zhong <chen.zhong@...iatek.com>,
	Matthias Brugger <matthias.bgg@...il.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH V4 2/2] regulator: mt6323: Add support for MT6323
 regulator

On Wed, Jan 27, 2016 at 01:00:59PM +0100, John Crispin wrote:

> +		/* Constrain board-specific capabilities according to what
> +		 * this driver and the chip itself can actually do.
> +		 */
> +		c = rdev->constraints;
> +		c->valid_modes_mask |= REGULATOR_MODE_NORMAL |
> +				       REGULATOR_MODE_STANDBY;
> +		c->valid_ops_mask |= REGULATOR_CHANGE_MODE;

No, drivers should *never* enable things that weren't explictly enabled
by the machine constraints.  This misses the whole point of having
constraints.  They are there so that the system integrator can enable
the functionality that is safe on a given board.  

The comment is also inaccurate, it claims it's imposing constraints but
in fact it's adding additional permissions.

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