From mboxrd@z Thu Jan  1 00:00:00 1970
From: Kevin Hilman <khilman@deeprootsystems.com>
Subject: Re: [PATCH 4/7] ARM: OMAP2+: powerdomain: introduce logic for finding valid power domain
Date: Wed, 27 Aug 2014 11:27:38 -0700
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To: Nishanth Menon <nm@ti.com>
Cc: Tony Lindgren <tony@atomide.com>, Tero Kristo <t-kristo@ti.com>, Paul Walmsley <paul@pwsan.com>, linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org, Keerthy <j-keerthy@ti.com>, =?utf-8?Q?Beno=C3=AEt?= Cousson <bcousson@baylibre.com>, Santosh Shilimkar <santosh.shilimkar@ti.com>
List-Id: linux-omap@vger.kernel.org

Nishanth Menon <nm@ti.com> writes:

> powerdomain configuration in OMAP is done using PWRSTCTRL register for
> each power domain. However, PRCM lets us write any value we'd like to
> the logic and power domain target states, however the SoC integration
> tends to actually function only at a few discrete states. These valid
> states are already in our powerdomains_xxx_data.c file.
>
> So, provide a function to easily query valid low power state that the
> power domain is allowed to go to.
>
> Based on work originally done by Jean Pihet <j-pihet@ti.com>
> https://patchwork.kernel.org/patch/1325091/ . There is no attempt to
> create a new powerdomain solution here, except fixing issues seen
> attempting invalid programming attempts. Future consolidation to the
> generic powerdomain framework should consider this requirement as
> well.
>
> Similar solutions have been done in product kernels in the past such
> as:
> https://android.googlesource.com/kernel/omap.git/+blame/android-omap-panda-3.0/arch/arm/mach-omap2/pm44xx.c
>
> Signed-off-by: Nishanth Menon <nm@ti.com>
> ---

nit: this is part of a fixes series, but it's more of a new feature.

That being said, the feature is needed and looks OK, except for...

> +up_search:
> +	/* OK, no deeper ones, can we get a higher match? */
> +	new_pwrst = req_state + 1;
> +	while (!(pwrdm_states & BIT(new_pwrst))) {
> +		/* BUG if we have messed up database */
> +		BUG_ON(new_pwrst > PWRDM_POWER_ON);

I don't think this is BUG() worthy, and should have a saner way to recover.

Kevin