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Date: Wed, 12 Sep 2012 16:07:13 -0600
From: Stephen Warren <swarren@...dotorg.org>
To: Alexandre Courbot <acourbot@...dia.com>
CC: Stephen Warren <swarren@...dia.com>,
Thierry Reding <thierry.reding@...onic-design.de>,
Simon Glass <sjg@...omium.org>,
Grant Likely <grant.likely@...retlab.ca>,
Rob Herring <rob.herring@...xeda.com>,
Mark Brown <broonie@...nsource.wolfsonmicro.com>,
Anton Vorontsov <cbou@...l.ru>,
David Woodhouse <dwmw2@...radead.org>,
Arnd Bergmann <arnd@...db.de>,
Leela Krishna Amudala <l.krishna@...sung.com>,
linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-fbdev@...r.kernel.org, devicetree-discuss@...ts.ozlabs.org,
linux-pm@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH v6 1/4] Runtime Interpreted Power Sequences
On 09/12/2012 03:57 AM, Alexandre Courbot wrote:
> Some device drivers (panel backlights especially) need to follow precise
> sequences for powering on and off, involving gpios, regulators, PWMs
> with a precise powering order and delays to respect between each steps.
> These sequences are board-specific, and do not belong to a particular
> driver - therefore they have been performed by board-specific hook
> functions to far.
>
> With the advent of the device tree and of ARM kernels that are not
> board-tied, we cannot rely on these board-specific hooks anymore but
> need a way to implement these sequences in a portable manner. This patch
> introduces a simple interpreter that can execute such power sequences
> encoded either as platform data or within the device tree.
>
> Signed-off-by: Alexandre Courbot <acourbot@...dia.com>
> diff --git a/Documentation/power/power_seq.txt b/Documentation/power/power_seq.txt
> +Sometimes, you may want to browse the list of resources allocated by a sequence,
> +for instance to ensure that a resource of a given type is present. The
> +power_seq_set_resources() function returns a list head that can be used with
> +the power_seq_for_each_resource() macro to browse all the resources of a set:
> +
> + struct list_head *power_seq_set_resources(struct power_seq_set *seqs);
I don't think you need to include that prototype here?
> + power_seq_for_each_resource(pos, seqs)
> +
> +Here "pos" will be a pointer to a struct power_seq_resource. This structure
> +contains the type of the resource, the information used for identifying it, and
> +the resolved resource itself.
> diff --git a/drivers/power/power_seq/Makefile b/drivers/power/power_seq/Makefile
> new file mode 100644
> index 0000000..f77a359
> --- /dev/null
> +++ b/drivers/power/power_seq/Makefile
> @@ -0,0 +1 @@
> +obj-$(CONFIG_POWER_SEQ) += power_seq.o
Don't you need to compile all the power_seq_*.c too?
Oh, I see the following in power_seq.c:
> +#include "power_seq_delay.c"
> +#include "power_seq_regulator.c"
> +#include "power_seq_pwm.c"
> +#include "power_seq_gpio.c"
It's probably better just to compile them separately and link them.
> diff --git a/drivers/power/power_seq/power_seq.c b/drivers/power/power_seq/power_seq.c
> +struct power_seq_step {
> + /* Copy of the platform data */
> + struct platform_power_seq_step pdata;
I'd reword the comment to "Copy of the step", and name the field "step".
> +static const struct power_seq_res_ops power_seq_types[POWER_SEQ_NUM_TYPES] = {
> + [POWER_SEQ_DELAY] = POWER_SEQ_DELAY_TYPE,
> + [POWER_SEQ_REGULATOR] = POWER_SEQ_REGULATOR_TYPE,
> + [POWER_SEQ_PWM] = POWER_SEQ_PWM_TYPE,
> + [POWER_SEQ_GPIO] = POWER_SEQ_GPIO_TYPE,
> +};
Ah, I see why you're using #include now.
> +MODULE_LICENSE("GPL");
s/GPL/GPL v2/ given the license header.
> diff --git a/drivers/power/power_seq/power_seq_gpio.c b/drivers/power/power_seq/power_seq_gpio.c
> +static int power_seq_res_alloc_gpio(struct device *dev,
> + struct platform_power_seq_step *pstep,
> + struct power_seq_resource *res)
> +{
> + int err;
> +
> + err = devm_gpio_request_one(dev, pstep->gpio.gpio,
> + GPIOF_OUT_INIT_LOW, dev_name(dev));
Hmm. The INIT_LOW part of that might be somewhat presumptive. I would
suggest simply requesting the GPIO here, and using
gpio_direction_output() in power_seq_step_run_gpio(), thus deferring the
decision of what value to set the GPIO to until a real sequence is
actually run.
> diff --git a/drivers/power/power_seq/power_seq_pwm.c b/drivers/power/power_seq/power_seq_pwm.c
> diff --git a/drivers/power/power_seq/power_seq_regulator.c b/drivers/power/power_seq/power_seq_regulator.c
> diff --git a/include/linux/power_seq.h b/include/linux/power_seq.h
> +#include <net/irda/parameters.h>
That looks out of place.
> +/**
> + * struct power_seq_resource - resource used by a power sequence set
> + * @pdata: Pointer to the platform data used to resolve this resource
> + * @regulator: Resolved regulator if of type POWER_SEQ_REGULATOR
> + * @pwm: Resolved PWM if of type POWER_SEQ_PWM
> + * @list: Used to link resources together
> + */
I think that kerneldoc is stale.
> +struct power_seq_resource {
> + enum power_seq_res_type type;
> + /* resolved resource and identifier */
> + union {
> + struct {
> + struct regulator *regulator;
> + const char *id;
> + } regulator;
> + struct {
> + struct pwm_device *pwm;
> + const char *id;
> + } pwm;
> + struct {
> + int gpio;
> + } gpio;
> + };
> + struct list_head list;
> +};
Aside from those minor issues, this all looks reasonable to me, so,
Reviewed-by: Stephen Warren <swarren@...dotorg.org>
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