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SubjectRe: [PATCH] leds: Add LED class driver for regulator driven LEDs.
On Wed, 2 Dec 2009 18:06:58 +0000
Mark Brown <broonie@opensource.wolfsonmicro.com> wrote:
> On Wed, Dec 02, 2009 at 06:40:25PM +0100, Antonio Ospite wrote:
>
> > A doubt I had was about leaving the 'supply' variable configurable from
> > platform data, or relying on some fixed value like "vled", but leaving it
> > configurable covers the case when we have different regulators used for
> > different LEDs or vibrators.
>
> There's no need to do this since the regulator API matches consumers
> based on struct device as well as name so you can have as many LEDs as
> you like all using the same supply name mapping to different regulators.
>

I need some more explanation here, I am currently using the driver with
this code:

+/* VVIB: Vibrator on A780, A1200, A910, E6, E2 */
+static struct regulator_consumer_supply pcap_regulator_VVIB_consumers
[] = {
+ { .dev_name = "leds-regulator", .supply = "vibrator", },
^^^^^^^^
+};
+
+static struct regulator_init_data pcap_regulator_VVIB_data = {
+ .constraints = {
+ .min_uV = 1300000,
+ .max_uV = 3000000,
+ .valid_ops_mask = REGULATOR_CHANGE_STATUS |
+ REGULATOR_CHANGE_VOLTAGE,
+ },
+ .num_consumer_supplies = ARRAY_SIZE
(pcap_regulator_VVIB_consumers),
+ .consumer_supplies = pcap_regulator_VVIB_consumers,
+};
@@ -749,6 +766,10 @@ static struct pcap_subdev a780_pcap_subdevs[] = {
.name = "pcap-regulator",
.id = VAUX3,
.platform_data = &pcap_regulator_VAUX3_data,
+ }, {
+ .name = "pcap-regulator",
+ .id = VVIB,
+ .platform_data = &pcap_regulator_VVIB_data,
},
};

and then:


@@ -872,8 +893,24 @@ static struct platform_device a780_camera = {
},
};

+/* vibrator */
+static struct led_regulator_platform_data a780_vibrator_data = {
+ .name = "a780::vibrator",
+ .supply = "vibrator"
^^^^^^^^ I'll get the regulator with this.
+};
+
+static struct platform_device a780_vibrator = {
+ .name = "leds-regulator",
+ .id = -1,
+ .dev = {
+ .platform_data = &a780_vibrator_data,
+ },
+};
+
+
static struct platform_device *a780_devices[] __initdata = {
&a780_gpio_keys,
+ &a780_vibrator
};

If I set the .supply value fixed, how can I assign different
regulators to different leds? Should I use the address to the platform
device (a780_vibrator in this case) for .dev when defining the
regulator in the first place?
> > Should I add a note in Documentation/ about how to use it? Tell me if so.
>
> If you wish to, it's not essential (only one existing LED driver appears
> to do this) and the comment in the header file is probably adequate.
>

Ok.

> > +static inline int led_regulator_get_max_brightness(struct regulator *supply)
> > +{
> > + return regulator_count_voltages(supply);
> > +}
>
> More graceful handling of regulators that don't implement list_voltage
> might be nice (for simple on/off control - not all regulators have
> configurable voltages). If a regulator doesn't support list_voltage
> you'll get -EINVAL.
>

Ok, I need to study the regulator framework a bit more, but I think I
got the logic you are referring to, if we can actually list voltages
then max_brightness is the number of voltages as it is now, else if we
can only change status then max_brightness is 1 (one).

> > + vcc = regulator_get(&pdev->dev, pdata->supply);
> > + if (IS_ERR(vcc)) {
> > + dev_err(&pdev->dev, "Cannot get vcc for %s\n", pdata->name);
> > + return PTR_ERR(vcc);;
> > + }
>
> You almost certainly want regulator_get_exclusive() here; this driver
> can't function properly if something else is using the regulator and
> holding the LED on or off without it. You'll also want to check the
> status of the LED on startup and update your internal status to match
> that.

Will do, thanks for reviewing the code.

Regards,
Antonio

--
Antonio Ospite
http://ao2.it

PGP public key ID: 0x4553B001

A: Because it messes up the order in which people normally read text.
See http://en.wikipedia.org/wiki/Posting_style
Q: Why is top-posting such a bad thing?
A: Top-posting.
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