The voltage and current regulators on the WM8350 AudioPlus PMIC can be
used in concert to provide a power efficient LED driver. This driver
implements support for this within the standard LED class.
Platform initialisation code should configure the LED hardware in the
init callback provided by the WM8350 core driver. The callback should
use wm8350_isink_set_flash(), wm8350_dcdc25_set_mode() and
wm8350_dcdc_set_slot() to configure the operating parameters of the
regulators for their hardware and then then use wm8350_register_led() to
instantiate the LED driver.
This driver was originally written by Liam Girdwood, though it has been
extensively modified since then.
Signed-off-by: Mark Brown <[email protected]>
---
drivers/leds/Kconfig | 7 +
drivers/leds/Makefile | 1 +
drivers/leds/leds-wm8350.c | 327 ++++++++++++++++++++++++++++++++++
drivers/mfd/wm8350-core.c | 3 +
drivers/regulator/wm8350-regulator.c | 89 +++++++++
include/linux/mfd/wm8350/pmic.h | 35 ++++
6 files changed, 462 insertions(+), 0 deletions(-)
create mode 100644 drivers/leds/leds-wm8350.c
diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index e7fb7d2..6a66ee8 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -158,6 +158,13 @@ config LEDS_PCA955X
LED driver chips accessed via the I2C bus. Supported
devices include PCA9550, PCA9551, PCA9552, and PCA9553.
+config LEDS_WM8350
+ tristate "LED Support for WM8350 AudioPlus PMIC"
+ depends on LEDS_CLASS && MFD_WM8350
+ help
+ This option enables support for LEDs driven by the Wolfson
+ Microelectronics WM8350 AudioPlus PMIC.
+
config LEDS_DA903X
tristate "LED Support for DA9030/DA9034 PMIC"
depends on LEDS_CLASS && PMIC_DA903X
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index e1967a2..d93f220 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -23,6 +23,7 @@ obj-$(CONFIG_LEDS_FSG) += leds-fsg.o
obj-$(CONFIG_LEDS_PCA955X) += leds-pca955x.o
obj-$(CONFIG_LEDS_DA903X) += leds-da903x.o
obj-$(CONFIG_LEDS_HP_DISK) += leds-hp-disk.o
+obj-$(CONFIG_LEDS_WM8350) += leds-wm8350.o
# LED Triggers
obj-$(CONFIG_LEDS_TRIGGER_TIMER) += ledtrig-timer.o
diff --git a/drivers/leds/leds-wm8350.c b/drivers/leds/leds-wm8350.c
new file mode 100644
index 0000000..f3e5af3
--- /dev/null
+++ b/drivers/leds/leds-wm8350.c
@@ -0,0 +1,327 @@
+/*
+ * LED driver for WM8350 driven LEDS.
+ *
+ * Copyright(C) 2007, 2008 Wolfson Microelectronics PLC.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/leds.h>
+#include <linux/err.h>
+#include <linux/mfd/wm8350/pmic.h>
+#include <linux/regulator/consumer.h>
+
+/* Microamps */
+static const int isink_cur[] = {
+ 4,
+ 5,
+ 6,
+ 7,
+ 8,
+ 10,
+ 11,
+ 14,
+ 16,
+ 19,
+ 23,
+ 27,
+ 32,
+ 39,
+ 46,
+ 54,
+ 65,
+ 77,
+ 92,
+ 109,
+ 130,
+ 154,
+ 183,
+ 218,
+ 259,
+ 308,
+ 367,
+ 436,
+ 518,
+ 616,
+ 733,
+ 872,
+ 1037,
+ 1233,
+ 1466,
+ 1744,
+ 2073,
+ 2466,
+ 2933,
+ 3487,
+ 4147,
+ 4932,
+ 5865,
+ 6975,
+ 8294,
+ 9864,
+ 11730,
+ 13949,
+ 16589,
+ 19728,
+ 23460,
+ 27899,
+ 33178,
+ 39455,
+ 46920,
+ 55798,
+ 66355,
+ 78910,
+ 93840,
+ 111596,
+ 132710,
+ 157820,
+ 187681,
+ 223191
+};
+
+#define to_wm8350_led(led_cdev) \
+ container_of(led_cdev, struct wm8350_led, cdev)
+
+static void wm8350_led_enable(struct wm8350_led *led)
+{
+ int ret;
+
+ if (led->enabled)
+ return;
+
+ ret = regulator_enable(led->isink);
+ if (ret != 0) {
+ dev_err(led->cdev.dev, "Failed to enable ISINK: %d\n", ret);
+ return;
+ }
+
+ ret = regulator_enable(led->dcdc);
+ if (ret != 0) {
+ dev_err(led->cdev.dev, "Failed to enable DCDC: %d\n", ret);
+ regulator_disable(led->isink);
+ return;
+ }
+
+ led->enabled = 1;
+}
+
+static void wm8350_led_disable(struct wm8350_led *led)
+{
+ int ret;
+
+ if (!led->enabled)
+ return;
+
+ ret = regulator_disable(led->dcdc);
+ if (ret != 0) {
+ dev_err(led->cdev.dev, "Failed to disable DCDC: %d\n", ret);
+ return;
+ }
+
+ ret = regulator_disable(led->isink);
+ if (ret != 0) {
+ dev_err(led->cdev.dev, "Failed to disable ISINK: %d\n", ret);
+ regulator_enable(led->isink);
+ return;
+ }
+
+ led->enabled = 0;
+}
+
+static void led_work(struct work_struct *work)
+{
+ struct wm8350_led *led = container_of(work, struct wm8350_led, work);
+ int ret;
+ int uA;
+
+ mutex_lock(&led->mutex);
+
+ if (led->value == LED_OFF) {
+ wm8350_led_disable(led);
+ goto out;
+ }
+
+ /* This scales linearly into the index of valid current
+ * settings which results in a linear scaling of perceived
+ * brightness due to the non-linear settings.
+ */
+ uA = (led->max_uA_index * led->value) / LED_FULL;
+ BUG_ON(uA > ARRAY_SIZE(isink_cur));
+ ret = regulator_set_current_limit(led->isink, isink_cur[uA],
+ isink_cur[uA]);
+ if (ret != 0)
+ dev_err(led->cdev.dev, "Failed to set %duA: %d\n",
+ isink_cur[uA], ret);
+
+ wm8350_led_enable(led);
+
+out:
+ mutex_unlock(&led->mutex);
+}
+
+static void wm8350_led_set(struct led_classdev *led_cdev,
+ enum led_brightness value)
+{
+ struct wm8350_led *led = to_wm8350_led(led_cdev);
+
+ mutex_lock(&led->mutex);
+ led->value = value;
+ mutex_unlock(&led->mutex);
+
+ schedule_work(&led->work);
+}
+
+#ifdef CONFIG_PM
+static int wm8350_led_suspend(struct platform_device *pdev, pm_message_t state)
+{
+ struct wm8350_led *led =
+ (struct wm8350_led *)platform_get_drvdata(pdev);
+
+ led_classdev_suspend(&led->cdev);
+ return 0;
+}
+
+static int wm8350_led_resume(struct platform_device *pdev)
+{
+ struct wm8350_led *led =
+ (struct wm8350_led *)platform_get_drvdata(pdev);
+
+ led_classdev_resume(&led->cdev);
+ return 0;
+}
+#else
+#define wm8350_led_suspend NULL
+#define wm8350_led_resume NULL
+#endif
+
+static void wm8350_led_shutdown(struct platform_device *pdev)
+{
+ struct wm8350_led *led =
+ (struct wm8350_led *)platform_get_drvdata(pdev);
+
+ mutex_lock(&led->mutex);
+ led->value = LED_OFF;
+ wm8350_led_disable(led);
+ mutex_unlock(&led->mutex);
+}
+
+static int wm8350_led_probe(struct platform_device *pdev)
+{
+ struct regulator *isink, *dcdc;
+ struct wm8350_led *led;
+ struct wm8350_led_platform_data *pdata = pdev->dev.platform_data;
+ int ret, i;
+
+ if (pdata == NULL) {
+ dev_err(&pdev->dev, "no platform data\n");
+ return -ENODEV;
+ }
+
+ if (pdata->max_uA < isink_cur[0]) {
+ dev_err(&pdev->dev, "Invalid maximum current %duA\n",
+ pdata->max_uA);
+ return -EINVAL;
+ }
+
+ isink = regulator_get(&pdev->dev, "led_isink");
+ if (IS_ERR(isink) || isink == NULL) {
+ printk(KERN_ERR "%s: cant get ISINK\n", __func__);
+ return PTR_ERR(isink);
+ }
+
+ dcdc = regulator_get(&pdev->dev, "led_vcc");
+ if (IS_ERR(dcdc) || dcdc == NULL) {
+ printk(KERN_ERR "%s: cant get DCDC\n", __func__);
+ regulator_put(isink);
+ return PTR_ERR(dcdc);
+ }
+
+ led = kzalloc(sizeof(*led), GFP_KERNEL);
+ if (led == NULL) {
+ regulator_put(isink);
+ regulator_put(dcdc);
+ return -ENOMEM;
+ }
+
+ led->cdev.brightness_set = wm8350_led_set;
+ led->cdev.default_trigger = (char *)pdata->default_trigger;
+ led->cdev.name = pdata->name;
+ led->enabled = regulator_is_enabled(isink);
+ led->isink = isink;
+ led->dcdc = dcdc;
+
+ for (i = 0; i < ARRAY_SIZE(isink_cur); i++)
+ if (isink_cur[i] >= pdata->max_uA)
+ break;
+ led->max_uA_index = i;
+ if (pdata->max_uA != isink_cur[i])
+ dev_warn(&pdev->dev,
+ "Maximum current %duA is not directly supported,"
+ " check platform data\n",
+ pdata->max_uA);
+
+ mutex_init(&led->mutex);
+ INIT_WORK(&led->work, led_work);
+ led->value = LED_OFF;
+ platform_set_drvdata(pdev, led);
+
+ ret = led_classdev_register(&pdev->dev, &led->cdev);
+ if (ret < 0) {
+ regulator_put(isink);
+ regulator_put(dcdc);
+ kfree(led);
+ return ret;
+ }
+
+ return 0;
+}
+
+static int wm8350_led_remove(struct platform_device *pdev)
+{
+ struct wm8350_led *led =
+ (struct wm8350_led *)platform_get_drvdata(pdev);
+
+ led_classdev_unregister(&led->cdev);
+ schedule_work(&led->work);
+ flush_scheduled_work();
+ wm8350_led_disable(led);
+ regulator_put(led->dcdc);
+ regulator_put(led->isink);
+ kfree(led);
+ return 0;
+}
+
+static struct platform_driver wm8350_led_driver = {
+ .driver = {
+ .name = "wm8350-led",
+ .owner = THIS_MODULE,
+ },
+ .probe = wm8350_led_probe,
+ .remove = wm8350_led_remove,
+ .shutdown = wm8350_led_shutdown,
+ .suspend = wm8350_led_suspend,
+ .resume = wm8350_led_resume,
+};
+
+static int __devinit wm8350_led_init(void)
+{
+ return platform_driver_register(&wm8350_led_driver);
+}
+module_init(wm8350_led_init);
+
+static void wm8350_led_exit(void)
+{
+ platform_driver_unregister(&wm8350_led_driver);
+}
+module_exit(wm8350_led_exit);
+
+MODULE_AUTHOR("Mark Brown");
+MODULE_DESCRIPTION("WM8350 LED driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:wm8350-led");
diff --git a/drivers/mfd/wm8350-core.c b/drivers/mfd/wm8350-core.c
index 0d47fb9..6004ff8 100644
--- a/drivers/mfd/wm8350-core.c
+++ b/drivers/mfd/wm8350-core.c
@@ -1257,6 +1257,9 @@ void wm8350_device_exit(struct wm8350 *wm8350)
{
int i;
+ for (i = 0; i < ARRAY_SIZE(wm8350->pmic.led); i++)
+ platform_device_unregister(wm8350->pmic.led[i].pdev);
+
for (i = 0; i < ARRAY_SIZE(wm8350->pmic.pdev); i++)
platform_device_unregister(wm8350->pmic.pdev[i]);
diff --git a/drivers/regulator/wm8350-regulator.c b/drivers/regulator/wm8350-regulator.c
index 1f44b17..53b81da 100644
--- a/drivers/regulator/wm8350-regulator.c
+++ b/drivers/regulator/wm8350-regulator.c
@@ -1405,6 +1405,95 @@ int wm8350_register_regulator(struct wm8350 *wm8350, int reg,
}
EXPORT_SYMBOL_GPL(wm8350_register_regulator);
+/**
+ * wm8350_register_led - Register a WM8350 LED output
+ *
+ * @param wm8350 The WM8350 device to configure.
+ * @param lednum LED device index to create.
+ * @param dcdc The DCDC to use for the LED.
+ * @param isink The ISINK to use for the LED.
+ * @param pdata Configuration for the LED.
+ *
+ * The WM8350 supports the use of an ISINK together with a DCDC to
+ * provide a power-efficient LED driver. This function registers the
+ * regulators and instantiates the platform device for a LED. The
+ * operating modes for the LED regulators must be configured using
+ * wm8350_isink_set_flash(), wm8350_dcdc25_set_mode() and
+ * wm8350_dcdc_set_slot() prior to calling this function.
+ */
+int wm8350_register_led(struct wm8350 *wm8350, int lednum, int dcdc, int isink,
+ struct wm8350_led_platform_data *pdata)
+{
+ struct wm8350_led *led = &wm8350->pmic.led[lednum];
+ struct platform_device *pdev;
+ int ret;
+
+ if (lednum > ARRAY_SIZE(wm8350->pmic.led) || lednum < 0) {
+ dev_err(wm8350->dev, "Invalid LED index %d\n", lednum);
+ return -ENODEV;
+ }
+
+ if (led->pdev) {
+ dev_err(wm8350->dev, "LED %d already allocated\n", lednum);
+ return -EINVAL;
+ }
+
+ pdev = platform_device_alloc("wm8350-led", lednum);
+ if (pdev == NULL) {
+ dev_err(wm8350->dev, "Failed to allocate LED %d\n", lednum);
+ return -ENOMEM;
+ }
+
+ led->isink_consumer.dev = &pdev->dev;
+ led->isink_consumer.supply = "led_isink";
+ led->isink_init.num_consumer_supplies = 1;
+ led->isink_init.consumer_supplies = &led->isink_consumer;
+ led->isink_init.constraints.min_uA = 0;
+ led->isink_init.constraints.max_uA = pdata->max_uA;
+ led->isink_init.constraints.valid_ops_mask = REGULATOR_CHANGE_CURRENT;
+ led->isink_init.constraints.valid_modes_mask = REGULATOR_MODE_NORMAL;
+ ret = wm8350_register_regulator(wm8350, isink, &led->isink_init);
+ if (ret != 0) {
+ platform_device_put(pdev);
+ return ret;
+ }
+
+ led->dcdc_consumer.dev = &pdev->dev;
+ led->dcdc_consumer.supply = "led_vcc";
+ led->dcdc_init.num_consumer_supplies = 1;
+ led->dcdc_init.consumer_supplies = &led->dcdc_consumer;
+ led->dcdc_init.constraints.valid_modes_mask = REGULATOR_MODE_NORMAL;
+ ret = wm8350_register_regulator(wm8350, dcdc, &led->dcdc_init);
+ if (ret != 0) {
+ platform_device_put(pdev);
+ return ret;
+ }
+
+ switch (isink) {
+ case WM8350_ISINK_A:
+ wm8350->pmic.isink_A_dcdc = dcdc;
+ break;
+ case WM8350_ISINK_B:
+ wm8350->pmic.isink_B_dcdc = dcdc;
+ break;
+ }
+
+ pdev->dev.platform_data = pdata;
+ pdev->dev.parent = wm8350->dev;
+ ret = platform_device_add(pdev);
+ if (ret != 0) {
+ dev_err(wm8350->dev, "Failed to register LED %d: %d\n",
+ lednum, ret);
+ platform_device_put(pdev);
+ return ret;
+ }
+
+ led->pdev = pdev;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(wm8350_register_led);
+
static struct platform_driver wm8350_regulator_driver = {
.probe = wm8350_regulator_probe,
.remove = wm8350_regulator_remove,
diff --git a/include/linux/mfd/wm8350/pmic.h b/include/linux/mfd/wm8350/pmic.h
index 69b69e0..bd8e1c4 100644
--- a/include/linux/mfd/wm8350/pmic.h
+++ b/include/linux/mfd/wm8350/pmic.h
@@ -13,6 +13,10 @@
#ifndef __LINUX_MFD_WM8350_PMIC_H
#define __LINUX_MFD_WM8350_PMIC_H
+#include <linux/platform_device.h>
+#include <linux/leds.h>
+#include <linux/regulator/machine.h>
+
/*
* Register values.
*/
@@ -700,6 +704,32 @@ struct wm8350;
struct platform_device;
struct regulator_init_data;
+/*
+ * WM8350 LED platform data
+ */
+struct wm8350_led_platform_data {
+ const char *name;
+ const char *default_trigger;
+ int max_uA;
+};
+
+struct wm8350_led {
+ struct platform_device *pdev;
+ struct mutex mutex;
+ struct work_struct work;
+ enum led_brightness value;
+ struct led_classdev cdev;
+ int max_uA_index;
+ int enabled;
+
+ struct regulator *isink;
+ struct regulator_consumer_supply isink_consumer;
+ struct regulator_init_data isink_init;
+ struct regulator *dcdc;
+ struct regulator_consumer_supply dcdc_consumer;
+ struct regulator_init_data dcdc_init;
+};
+
struct wm8350_pmic {
/* ISINK to DCDC mapping */
int isink_A_dcdc;
@@ -713,10 +743,15 @@ struct wm8350_pmic {
/* regulator devices */
struct platform_device *pdev[NUM_WM8350_REGULATORS];
+
+ /* LED devices */
+ struct wm8350_led led[2];
};
int wm8350_register_regulator(struct wm8350 *wm8350, int reg,
struct regulator_init_data *initdata);
+int wm8350_register_led(struct wm8350 *wm8350, int lednum, int dcdc, int isink,
+ struct wm8350_led_platform_data *pdata);
/*
* Additional DCDC control not supported via regulator API
--
1.5.6.5
LED API functions aren't allowed to sleep so we can't take a lock when
setting the brightness of the LED.
Signed-off-by: Mark Brown <[email protected]>
---
Sorry, I managed to drop this fix when moving the driver over to
mainline for submission. I'll roll it into the original patch in any
future submissions.
drivers/leds/leds-wm8350.c | 3 ---
1 files changed, 0 insertions(+), 3 deletions(-)
diff --git a/drivers/leds/leds-wm8350.c b/drivers/leds/leds-wm8350.c
index f3e5af3..283625c 100644
--- a/drivers/leds/leds-wm8350.c
+++ b/drivers/leds/leds-wm8350.c
@@ -170,10 +170,7 @@ static void wm8350_led_set(struct led_classdev *led_cdev,
{
struct wm8350_led *led = to_wm8350_led(led_cdev);
- mutex_lock(&led->mutex);
led->value = value;
- mutex_unlock(&led->mutex);
-
schedule_work(&led->work);
}
--
1.5.6.5
On Thu, 13 Nov 2008 12:39:57 +0000
Mark Brown <[email protected]> wrote:
> The voltage and current regulators on the WM8350 AudioPlus PMIC can be
> used in concert to provide a power efficient LED driver. This driver
> implements support for this within the standard LED class.
>
> Platform initialisation code should configure the LED hardware in the
> init callback provided by the WM8350 core driver. The callback should
> use wm8350_isink_set_flash(), wm8350_dcdc25_set_mode() and
> wm8350_dcdc_set_slot() to configure the operating parameters of the
> regulators for their hardware and then then use wm8350_register_led() to
> instantiate the LED driver.
>
> This driver was originally written by Liam Girdwood, though it has been
> extensively modified since then.
>
> ...
>
> +static void wm8350_led_disable(struct wm8350_led *led)
> +{
> + int ret;
> +
> + if (!led->enabled)
> + return;
> +
> + ret = regulator_disable(led->dcdc);
> + if (ret != 0) {
> + dev_err(led->cdev.dev, "Failed to disable DCDC: %d\n", ret);
> + return;
> + }
> +
> + ret = regulator_disable(led->isink);
> + if (ret != 0) {
> + dev_err(led->cdev.dev, "Failed to disable ISINK: %d\n", ret);
> + regulator_enable(led->isink);
Should be regulator_enable(led->dcdc), yes?
> + return;
> + }
> +
> + led->enabled = 0;
> +}
> +
>
> ...
>
> +static int wm8350_led_remove(struct platform_device *pdev)
> +{
> + struct wm8350_led *led =
> + (struct wm8350_led *)platform_get_drvdata(pdev);
unneeded and undesirable cast of void*.
> + led_classdev_unregister(&led->cdev);
> + schedule_work(&led->work);
> + flush_scheduled_work();
The schedule_work() is unexpected and I can't immediately see why it's
here. If it is indeed correct, I'd suggest the addition of a comment.
> + wm8350_led_disable(led);
> + regulator_put(led->dcdc);
> + regulator_put(led->isink);
> + kfree(led);
> + return 0;
> +}
> +
On Thu 2008-11-13 12:39:57, Mark Brown wrote:
> The voltage and current regulators on the WM8350 AudioPlus PMIC can be
> used in concert to provide a power efficient LED driver. This driver
> implements support for this within the standard LED class.
>
> Platform initialisation code should configure the LED hardware in the
> init callback provided by the WM8350 core driver. The callback should
> use wm8350_isink_set_flash(), wm8350_dcdc25_set_mode() and
> wm8350_dcdc_set_slot() to configure the operating parameters of the
> regulators for their hardware and then then use wm8350_register_led() to
> instantiate the LED driver.
What kind of hw is this? 1W led attached to some kind of PDA?
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
On Thu 2008-11-13 14:57:49, Mark Brown wrote:
> LED API functions aren't allowed to sleep so we can't take a lock when
> setting the brightness of the LED.
>
> Signed-off-by: Mark Brown <[email protected]>
> ---
>
> Sorry, I managed to drop this fix when moving the driver over to
> mainline for submission. I'll roll it into the original patch in any
> future submissions.
>
> drivers/leds/leds-wm8350.c | 3 ---
> 1 files changed, 0 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/leds/leds-wm8350.c b/drivers/leds/leds-wm8350.c
> index f3e5af3..283625c 100644
> --- a/drivers/leds/leds-wm8350.c
> +++ b/drivers/leds/leds-wm8350.c
> @@ -170,10 +170,7 @@ static void wm8350_led_set(struct led_classdev *led_cdev,
> {
> struct wm8350_led *led = to_wm8350_led(led_cdev);
>
> - mutex_lock(&led->mutex);
> led->value = value;
> - mutex_unlock(&led->mutex);
> -
> schedule_work(&led->work);
> }
Unfortunately, now you write to value w/o locking -> races
possible. Maybe you need to make value atomic_t?
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
On Sat, Nov 15, 2008 at 06:29:45PM +0100, Pavel Machek wrote:
> On Thu 2008-11-13 12:39:57, Mark Brown wrote:
> > regulators for their hardware and then then use wm8350_register_led() to
> > instantiate the LED driver.
> What kind of hw is this? 1W led attached to some kind of PDA?
Depends on the hardware design - this is a generic component for battery
powered devices (including PDAs). Typical applications include
relatively high power things like backlights.
On Sat, Nov 15, 2008 at 06:31:10PM +0100, Pavel Machek wrote:
> Unfortunately, now you write to value w/o locking -> races
> possible. Maybe you need to make value atomic_t?
Yes, that'd be safer though I'd be surprised to see systems that could
trigger it.
On Sat 2008-11-15 17:50:50, Mark Brown wrote:
> On Sat, Nov 15, 2008 at 06:31:10PM +0100, Pavel Machek wrote:
>
> > Unfortunately, now you write to value w/o locking -> races
> > possible. Maybe you need to make value atomic_t?
>
> Yes, that'd be safer though I'd be surprised to see systems that could
> trigger it.
Yes, they are uncommon. They exist; SPARC, IIRC. Plus you need
barriers on anything SMP... Just use atomic_t.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
On Sat, Nov 15, 2008 at 07:51:20PM +0100, Pavel Machek wrote:
> On Sat 2008-11-15 17:50:50, Mark Brown wrote:
> > Yes, that'd be safer though I'd be surprised to see systems that could
> > trigger it.
> Yes, they are uncommon. They exist; SPARC, IIRC. Plus you need
Exceptionally uncommon with the systems the WM8350 gets used with -
it's a primary PMIC for mobile devices so anything other than
uniprocessor ARM would be surprising.
> barriers on anything SMP... Just use atomic_t.
I was intending to do so next time I spin the patch. Andrew had some
other comments and I don't have any test systems when I'm not in the
office anyway.
On Fri, Nov 14, 2008 at 03:19:08PM -0800, Andrew Morton wrote:
> > + led_classdev_unregister(&led->cdev);
> > + schedule_work(&led->work);
> > + flush_scheduled_work();
> The schedule_work() is unexpected and I can't immediately see why it's
> here. If it is indeed correct, I'd suggest the addition of a comment.
Me either, I'll remove it and fix the other things you raised too.
Thanks.
On Sat, 2008-11-15 at 19:14 +0000, Mark Brown wrote:
> On Sat, Nov 15, 2008 at 07:51:20PM +0100, Pavel Machek wrote:
> > On Sat 2008-11-15 17:50:50, Mark Brown wrote:
>
> > > Yes, that'd be safer though I'd be surprised to see systems that could
> > > trigger it.
>
> > Yes, they are uncommon. They exist; SPARC, IIRC. Plus you need
>
> Exceptionally uncommon with the systems the WM8350 gets used with -
> it's a primary PMIC for mobile devices so anything other than
> uniprocessor ARM would be surprising.
>
> > barriers on anything SMP... Just use atomic_t.
>
> I was intending to do so next time I spin the patch. Andrew had some
> other comments and I don't have any test systems when I'm not in the
> office anyway.
I've not looked in detail at the code but it looks like a maximum of a
32 bit value where you don't actually care which write succeeds as long
as it takes one of the values written? I don't see why that particular
variable needs any locking or to be atomic?
Cheers,
Richard
On Mon, Nov 17, 2008 at 03:33:15PM +0000, Richard Purdie wrote:
> I've not looked in detail at the code but it looks like a maximum of a
> 32 bit value where you don't actually care which write succeeds as long
> as it takes one of the values written? I don't see why that particular
Pretty much (it's an enum led_brightness) - it's just a standard LED
that can't be written without taking interrupts along the lines of the
GPIO LED driver.
> variable needs any locking or to be atomic?
I'd certainly be surprised if it were an issue in any practical system.
On Mon 2008-11-17 15:33:15, Richard Purdie wrote:
> On Sat, 2008-11-15 at 19:14 +0000, Mark Brown wrote:
> > On Sat, Nov 15, 2008 at 07:51:20PM +0100, Pavel Machek wrote:
> > > On Sat 2008-11-15 17:50:50, Mark Brown wrote:
> >
> > > > Yes, that'd be safer though I'd be surprised to see systems that could
> > > > trigger it.
> >
> > > Yes, they are uncommon. They exist; SPARC, IIRC. Plus you need
> >
> > Exceptionally uncommon with the systems the WM8350 gets used with -
> > it's a primary PMIC for mobile devices so anything other than
> > uniprocessor ARM would be surprising.
> >
> > > barriers on anything SMP... Just use atomic_t.
> >
> > I was intending to do so next time I spin the patch. Andrew had some
> > other comments and I don't have any test systems when I'm not in the
> > office anyway.
>
> I've not looked in detail at the code but it looks like a maximum of a
> 32 bit value where you don't actually care which write succeeds as long
> as it takes one of the values written? I don't see why that particular
> variable needs any locking or to be atomic?
Yes.. but it would hurt if you find 42 there, right? So atomic_t is
safer. gcc is alowed to do fancy optimalizations on plain integers....
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html