On 05/20/2015 05:19 PM, Stas Sergeev wrote:
Add LED_BRIGHTNESS_FAST flag. This flag is used to mark the led drivers
that do not use waiting operations when setting led brightness and do not
use work-queue in .brightness_set op.
When this flag is not set, disallow the blink periods smaller than 10mS
(LED_SLOW_MIN_PERIOD define).
CC: Bryan Wu <cooloney@xxxxxxxxx>
CC: Richard Purdie <rpurdie@xxxxxxxxx>
CC: Jacek Anaszewski <j.anaszewski@xxxxxxxxxxx>
CC: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
CC: linux-leds@xxxxxxxxxxxxxxx
CC: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Stas Sergeev <stsp@xxxxxxxxxxxxxxxxxxxxx>
---
drivers/leds/led-core.c | 30 +++++++++++++++++++-----------
drivers/leds/led-triggers.c | 8 +++++---
drivers/leds/trigger/ledtrig-oneshot.c | 5 ++++-
drivers/leds/trigger/ledtrig-timer.c | 18 +++++++++++++-----
include/linux/leds.h | 12 ++++++++++--
5 files changed, 51 insertions(+), 22 deletions(-)
diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index 9886dac..89241aa 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -25,12 +25,19 @@ EXPORT_SYMBOL_GPL(leds_list_lock);
LIST_HEAD(leds_list);
EXPORT_SYMBOL_GPL(leds_list);
-static void led_set_software_blink(struct led_classdev *led_cdev,
+static int led_set_software_blink(struct led_classdev *led_cdev,
unsigned long delay_on,
unsigned long delay_off)
{
int current_brightness;
+ if (!(led_cdev->flags & LED_BRIGHTNESS_FAST)) {
+ if (delay_on < LED_SLOW_MIN_PERIOD)
+ return -ERANGE;
+ if (delay_off < LED_SLOW_MIN_PERIOD)
+ return -ERANGE;
+ }
+
With this approach, the LED will remain in its current blink state, in
case LED_BRIGHTNESS_FAST flag is not set and delay to be set is below
LED_SLOW_MIN_PERIOD. This is because timer is deleted at the beginning
of led_blink_set. Effectively this can result in the LED staying turned
on when e.g. "echo 1 > delay_on" fails.
I propose to change this part of code as follows:
if (!(led_cdev->flags & LED_BRIGHTNESS_FAST)) {
if (delay_on < LED_SLOW_MIN_PERIOD ||
delay_off < LED_SLOW_MIN_PERIOD)
led_set_brightness_async(led_cdev, LED_OFF);
return -ERANGE;
}
}
By this occasion it turned out that we have inconsistency:
led_set_brightness_async calls brightness_set op, which doesn't
set LED brightness in an asynchronous way in case of every driver.
Before introduction of SET_BRIGHTNESS_SYNC and SET_BRIGHTNESS_ASYNC
flags there was only brightness_set op. The flags and
brightness_set_sync op was added for flash LED controllers to avoid
delegating the job to work queue and assure that brightness is set
as quickly as possible.
I mistakenly assumed that all drivers set the brightness with use
of a work queue.
Now, to fix the issue all drivers that set brightness in the
asynchronous way need to set the SET_BRIGHTNESS_SYNC flag and rename
their brightness_set ops to brightness_set_sync.
It would be also nice to rename brightness_set op to
brightness_set_async.
Also, led_set_brightness_async shouldn't be called directly
anywhere, but led_set_brightness should be used, as it
selects the appropriate op basing on the SET_BRIGHTNESS_* flag.
I'd prefer to do these modifications before merging this patch
set. I can produce the patch set within a few days. Or, maybe you
would like to take care of it?
current_brightness = led_get_brightness(led_cdev);
if (current_brightness)
led_cdev->blink_brightness = current_brightness;
@@ -43,36 +50,37 @@ static void led_set_software_blink(struct led_classdev *led_cdev,
/* never on - just set to off */
if (!delay_on) {
led_set_brightness_async(led_cdev, LED_OFF);
- return;
+ return 0;
}
/* never off - just set to brightness */
if (!delay_off) {
led_set_brightness_async(led_cdev, led_cdev->blink_brightness);
- return;
+ return 0;
}
mod_timer(&led_cdev->blink_timer, jiffies + 1);
+ return 0;
}
-static void led_blink_setup(struct led_classdev *led_cdev,
+static int led_blink_setup(struct led_classdev *led_cdev,
unsigned long *delay_on,
unsigned long *delay_off)
{
if (!(led_cdev->flags & LED_BLINK_ONESHOT) &&
led_cdev->blink_set &&
!led_cdev->blink_set(led_cdev, delay_on, delay_off))
- return;
+ return 0;
/* blink with 1 Hz as default if nothing specified */
if (!*delay_on && !*delay_off)
*delay_on = *delay_off = 500;
- led_set_software_blink(led_cdev, *delay_on, *delay_off);
+ return led_set_software_blink(led_cdev, *delay_on, *delay_off);
}
-void led_blink_set(struct led_classdev *led_cdev,
+int led_blink_set(struct led_classdev *led_cdev,
unsigned long *delay_on,
unsigned long *delay_off)
{
@@ -81,18 +89,18 @@ void led_blink_set(struct led_classdev *led_cdev,
led_cdev->flags &= ~LED_BLINK_ONESHOT;
led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
- led_blink_setup(led_cdev, delay_on, delay_off);
+ return led_blink_setup(led_cdev, delay_on, delay_off);
}
EXPORT_SYMBOL(led_blink_set);
-void led_blink_set_oneshot(struct led_classdev *led_cdev,
+int led_blink_set_oneshot(struct led_classdev *led_cdev,
unsigned long *delay_on,
unsigned long *delay_off,
int invert)
{
if ((led_cdev->flags & LED_BLINK_ONESHOT) &&
timer_pending(&led_cdev->blink_timer))
- return;
+ return -EBUSY;
led_cdev->flags |= LED_BLINK_ONESHOT;
led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
@@ -102,7 +110,7 @@ void led_blink_set_oneshot(struct led_classdev *led_cdev,
else
led_cdev->flags &= ~LED_BLINK_INVERT;
- led_blink_setup(led_cdev, delay_on, delay_off);
+ return led_blink_setup(led_cdev, delay_on, delay_off);
}
EXPORT_SYMBOL(led_blink_set_oneshot);
diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
index e8b1120..63305b1 100644
--- a/drivers/leds/led-triggers.c
+++ b/drivers/leds/led-triggers.c
@@ -272,6 +272,7 @@ static void led_trigger_blink_setup(struct led_trigger *trig,
int oneshot,
int invert)
{
+ int ret = 0;
struct led_classdev *led_cdev;
if (!trig)
@@ -280,12 +281,13 @@ static void led_trigger_blink_setup(struct led_trigger *trig,
read_lock(&trig->leddev_list_lock);
list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list) {
if (oneshot)
- led_blink_set_oneshot(led_cdev, delay_on, delay_off,
- invert);
+ ret = led_blink_set_oneshot(led_cdev, delay_on,
+ delay_off, invert);
else
- led_blink_set(led_cdev, delay_on, delay_off);
+ ret = led_blink_set(led_cdev, delay_on, delay_off);
}
read_unlock(&trig->leddev_list_lock);
+ WARN_ON(ret);
}
void led_trigger_blink(struct led_trigger *trig,
diff --git a/drivers/leds/trigger/ledtrig-oneshot.c b/drivers/leds/trigger/ledtrig-oneshot.c
index fbd02cd..ba91838 100644
--- a/drivers/leds/trigger/ledtrig-oneshot.c
+++ b/drivers/leds/trigger/ledtrig-oneshot.c
@@ -29,12 +29,15 @@ struct oneshot_trig_data {
static ssize_t led_shot(struct device *dev,
struct device_attribute *attr, const char *buf, size_t size)
{
+ ssize_t ret;
struct led_classdev *led_cdev = dev_get_drvdata(dev);
struct oneshot_trig_data *oneshot_data = led_cdev->trigger_data;
- led_blink_set_oneshot(led_cdev,
+ ret = led_blink_set_oneshot(led_cdev,
&led_cdev->blink_delay_on, &led_cdev->blink_delay_off,
oneshot_data->invert);
+ if (ret)
+ return ret;
/* content is ignored */
return size;
diff --git a/drivers/leds/trigger/ledtrig-timer.c b/drivers/leds/trigger/ledtrig-timer.c
index 8d09327..edc0c7f 100644
--- a/drivers/leds/trigger/ledtrig-timer.c
+++ b/drivers/leds/trigger/ledtrig-timer.c
@@ -31,13 +31,15 @@ static ssize_t led_delay_on_store(struct device *dev,
{
struct led_classdev *led_cdev = dev_get_drvdata(dev);
unsigned long state;
- ssize_t ret = -EINVAL;
+ ssize_t ret;
ret = kstrtoul(buf, 10, &state);
if (ret)
return ret;
- led_blink_set(led_cdev, &state, &led_cdev->blink_delay_off);
+ ret = led_blink_set(led_cdev, &state, &led_cdev->blink_delay_off);
+ if (ret)
+ return ret;
led_cdev->blink_delay_on = state;
return size;
@@ -56,13 +58,15 @@ static ssize_t led_delay_off_store(struct device *dev,
{
struct led_classdev *led_cdev = dev_get_drvdata(dev);
unsigned long state;
- ssize_t ret = -EINVAL;
+ ssize_t ret;
ret = kstrtoul(buf, 10, &state);
if (ret)
return ret;
- led_blink_set(led_cdev, &led_cdev->blink_delay_on, &state);
+ ret = led_blink_set(led_cdev, &led_cdev->blink_delay_on, &state);
+ if (ret)
+ return ret;
led_cdev->blink_delay_off = state;
return size;
@@ -84,12 +88,16 @@ static void timer_trig_activate(struct led_classdev *led_cdev)
if (rc)
goto err_out_delayon;
- led_blink_set(led_cdev, &led_cdev->blink_delay_on,
+ rc = led_blink_set(led_cdev, &led_cdev->blink_delay_on,
&led_cdev->blink_delay_off);
+ if (rc)
+ goto err_out_delayoff;
led_cdev->activated = true;
return;
+err_out_delayoff:
+ device_remove_file(led_cdev->dev, &dev_attr_delay_off);
err_out_delayon:
device_remove_file(led_cdev->dev, &dev_attr_delay_on);
}
diff --git a/include/linux/leds.h b/include/linux/leds.h
index b122eea..d3c6c2e 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -48,6 +48,10 @@ struct led_classdev {
#define SET_BRIGHTNESS_ASYNC (1 << 21)
#define SET_BRIGHTNESS_SYNC (1 << 22)
#define LED_DEV_CAP_FLASH (1 << 23)
+#define LED_BRIGHTNESS_FAST (1 << 24)
+
+/* safe period value for slow leds is 10mS */
+#define LED_SLOW_MIN_PERIOD 10
/* Set LED brightness level */
/* Must not sleep, use a workqueue if needed */
@@ -127,8 +131,10 @@ extern void led_classdev_resume(struct led_classdev *led_cdev);
* Note that if software blinking is active, simply calling
* led_cdev->brightness_set() will not stop the blinking,
* use led_classdev_brightness_set() instead.
+ *
+ * Returns: 0 on success or negative error value on failure
*/
-extern void led_blink_set(struct led_classdev *led_cdev,
+extern int led_blink_set(struct led_classdev *led_cdev,
unsigned long *delay_on,
unsigned long *delay_off);
/**
@@ -144,8 +150,10 @@ extern void led_blink_set(struct led_classdev *led_cdev,
*
* If invert is set, led blinks for delay_off first, then for
* delay_on and leave the led on after the on-off cycle.
+ *
+ * Returns: 0 on success or negative error value on failure
*/
-extern void led_blink_set_oneshot(struct led_classdev *led_cdev,
+extern int led_blink_set_oneshot(struct led_classdev *led_cdev,
unsigned long *delay_on,
unsigned long *delay_off,
int invert);
--
Best Regards,
Jacek Anaszewski
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