linux-kernel - Re: [PATCH v4 1/3] power-domain: add power domain drivers for Rockchip platform

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Date:	Mon, 20 Oct 2014 14:31:17 -0700
From:	Kevin Hilman <khilman@...nel.org>
To:	"jinkun.hong" <jinkun.hong@...k-chips.com>
Cc:	linus.walleij@...aro.org, linux-arm-kernel@...ts.infradead.org,
	Russell King <linux@....linux.org.uk>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Grant Likely <grant.likely@...aro.org>,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	Randy Dunlap <rdunlap@...radead.org>,
	linux-doc@...r.kernel.org, dianders@...omium.org,
	Heiko Stuebner <heiko@...ech.de>,
	linux-rockchip@...ts.infradead.org,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Jack Dai <jack.dai@...k-chips.com>
Subject: Re: [PATCH v4 1/3] power-domain: add power domain drivers for Rockchip platform

"jinkun.hong" <jinkun.hong@...k-chips.com> writes:

> From: "jinkun.hong" <jinkun.hong@...k-chips.com>
>
> Add power domain drivers based on generic power domain for Rockchip platform,
> and support RK3288.
>
> Signed-off-by: Jack Dai <jack.dai@...k-chips.com>
> Signed-off-by: jinkun.hong <jinkun.hong@...k-chips.com>

[...]

> +static int rockchip_pmu_set_idle_request(struct rockchip_domain *pd,
> +					 bool idle)
> +{
> +	u32 idle_mask = BIT(pd->idle_shift);
> +	u32 idle_target = idle << (pd->idle_shift);
> +	u32 ack_mask = BIT(pd->ack_shift);
> +	u32 ack_target = idle << (pd->ack_shift);
> +	unsigned int mask = BIT(pd->req_shift);
> +	unsigned int val;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&pd->idle_lock, flags);
> +	val = (idle) ? mask : 0;
> +	regmap_update_bits(pd->regmap_pmu, REQ_OFFSET, mask, val);
> +	dsb();

A summary of the locking and barriers here (or in changelog) would be
helpful for reviewers to verify you're protecting what you need to
protect.

> +	do {
> +		regmap_read(pd->regmap_pmu, ACK_OFFSET, &val);
> +	} while ((val & ack_mask) != ack_target);
> +
> +	do {
> +		regmap_read(pd->regmap_pmu, IDLE_OFFSET, &val);
> +	} while ((val & idle_mask) != idle_target);
> +
> +	spin_unlock_irqrestore(&pd->idle_lock, flags);

These IRQ-disabled while loops look like opportunities to lockup the
system.  Maybe add a timeout or a maximum number of tries?

> +	return 0;
> +}

Kevin
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