linux-kernel - Re: [v3,2/6] power: add power sequence library

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Date:	Fri, 29 Jul 2016 13:06:48 -0700
From:	Matthias Kaehlcke <mka@...omium.org>
To:	Peter Chen <peter.chen@....com>, gregkh@...uxfoundation.org,
	stern@...land.harvard.edu, ulf.hansson@...aro.org,
	broonie@...nel.org, sre@...nel.org, robh+dt@...nel.org,
	shawnguo@...nel.org, dbaryshkov@...il.com, dwmw2@...radead.org
Cc:	k.kozlowski@...sung.com, linux-arm-kernel@...ts.infradead.org,
	p.zabel@...gutronix.de, devicetree@...r.kernel.org,
	pawel.moll@....com, mark.rutland@....com,
	linux-usb@...r.kernel.org, arnd@...db.de, s.hauer@...gutronix.de,
	mail@...iej.szmigiero.name, troy.kisky@...ndarydevices.com,
	festevam@...il.com, oscar@...andei.net, stephen.boyd@...aro.org,
	linux-pm@...r.kernel.org, stillcompiling@...il.com,
	linux-kernel@...r.kernel.org
Subject: Re: [v3,2/6] power: add power sequence library

Hi Peter,

Thanks for your work on this, a few comments inline


On 07/20/2016 02:40 AM, Peter Chen wrote:

> ...
>
> +static int pwrseq_generic_on(struct device_node *np, struct pwrseq *pwrseq)
> +{
>
> ...
>
> +	if (gpiod_reset) {
> +		u32 duration_us = 50;
> +
> +		of_property_read_u32(np, "reset-duration-us",
> +				&duration_us);
> +		usleep_range(duration_us, duration_us + 10);
The end of the range could allow for more margin. Also consider busy 
looping for very short delays as in 
http://lxr.free-electrons.com/source/drivers/regulator/core.c#L2062
> ...
>
> +static int pwrseq_generic_get(struct device_node *np, struct pwrseq *pwrseq)
> +{
> +	struct pwrseq_generic *pwrseq_gen = to_generic_pwrseq(pwrseq);
> +	enum of_gpio_flags flags;
> +	int reset_gpio, ret = 0;
> +
> +	pwrseq_gen->clk = of_clk_get_by_name(np, NULL);
This only gets the first of potentially multiple clocks, is that intended?