Hi David,
Thanks for the patch. I have one reservation below.
On 04/30/2017 11:37 PM, David Lin wrote:
> This patch adds a hrtimer to ledtrig-transient so that when driver is
> registered with LED_BRIGHTNESS_FAST, the hrtimer is used for the better
> time accuracy in handling the duration.
>
> Signed-off-by: David Lin <dtw...@google.com>
> ---
> drivers/leds/trigger/ledtrig-transient.c | 59
> +++++++++++++++++++++++++++++---
> 1 file changed, 54 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/leds/trigger/ledtrig-transient.c
> b/drivers/leds/trigger/ledtrig-transient.c
> index 7e6011bd3646..63be54772596 100644
> --- a/drivers/leds/trigger/ledtrig-transient.c
> +++ b/drivers/leds/trigger/ledtrig-transient.c
> @@ -24,15 +24,18 @@
> #include <linux/device.h>
> #include <linux/slab.h>
> #include <linux/timer.h>
> +#include <linux/hrtimer.h>
> #include <linux/leds.h>
> #include "../leds.h"
>
> struct transient_trig_data {
> + struct led_classdev *led_cdev;
> int activate;
> int state;
> int restore_state;
> unsigned long duration;
> struct timer_list timer;
> + struct hrtimer hrtimer;
> };
>
> static void transient_timer_function(unsigned long data)
> @@ -44,6 +47,54 @@ static void transient_timer_function(unsigned long data)
> led_set_brightness_nosleep(led_cdev, transient_data->restore_state);
> }
>
> +static enum hrtimer_restart transient_hrtimer_function(struct hrtimer *timer)
> +{
> + struct transient_trig_data *transient_data =
> + container_of(timer, struct transient_trig_data, hrtimer);
> +
> + transient_timer_function((unsigned long)transient_data->led_cdev);
> +
> + return HRTIMER_NORESTART;
> +}
> +
> +static inline void transient_timer_setup(struct led_classdev *led_cdev)
> +{
> + struct transient_trig_data *tdata = led_cdev->trigger_data;
> +
> + if (led_cdev->flags & LED_BRIGHTNESS_FAST) {
> + tdata->led_cdev = led_cdev;
> + hrtimer_init(&tdata->hrtimer, CLOCK_MONOTONIC,
> + HRTIMER_MODE_REL);
> + tdata->hrtimer.function = transient_hrtimer_function;
> + } else {
> + setup_timer(&tdata->timer, transient_timer_function,
> + (unsigned long)led_cdev);
> + }
> +}
> +
> +static inline void transient_timer_start(struct led_classdev *led_cdev)
> +{
> + struct transient_trig_data *tdata = led_cdev->trigger_data;
> +
> + if (led_cdev->flags & LED_BRIGHTNESS_FAST) {
> + hrtimer_start(&tdata->hrtimer, ms_to_ktime(tdata->duration),
> + HRTIMER_MODE_REL);
> + } else {
> + mod_timer(&tdata->timer,
> + jiffies + msecs_to_jiffies(tdata->duration));
> + }
> +}
> +
> +static inline void transient_timer_cancel(struct led_classdev *led_cdev)
> +{
> + struct transient_trig_data *tdata = led_cdev->trigger_data;
> +
> + if (led_cdev->flags & LED_BRIGHTNESS_FAST)
> + hrtimer_cancel(&tdata->hrtimer);
> + else
> + del_timer_sync(&tdata->timer);
> +}
These functions don't seem to be good candidates for marking them with
inline modifier due to below reasons:
- they have more than three lines of code
- their parameters are not compiletime constants
- the functions are static and used only once - in this case
gcc is capable of inlining them automatically without help
This is concise excerpt from the Documentation/process/coding-style.rst,
chapter 15.
> static ssize_t transient_activate_show(struct device *dev,
> struct device_attribute *attr, char *buf)
> {
> @@ -70,7 +121,7 @@ static ssize_t transient_activate_store(struct device *dev,
>
> /* cancel the running timer */
> if (state == 0 && transient_data->activate == 1) {
> - del_timer(&transient_data->timer);
> + transient_timer_cancel(led_cdev);
> transient_data->activate = state;
> led_set_brightness_nosleep(led_cdev,
> transient_data->restore_state);
> @@ -84,8 +135,7 @@ static ssize_t transient_activate_store(struct device *dev,
> led_set_brightness_nosleep(led_cdev, transient_data->state);
> transient_data->restore_state =
> (transient_data->state == LED_FULL) ? LED_OFF : LED_FULL;
> - mod_timer(&transient_data->timer,
> - jiffies + msecs_to_jiffies(transient_data->duration));
> + transient_timer_start(led_cdev);
> }
>
> /* state == 0 && transient_data->activate == 0
> @@ -182,8 +232,7 @@ static void transient_trig_activate(struct led_classdev
> *led_cdev)
> if (rc)
> goto err_out_state;
>
> - setup_timer(&tdata->timer, transient_timer_function,
> - (unsigned long) led_cdev);
> + transient_timer_setup(led_cdev);
> led_cdev->activated = true;
>
> return;
>
--
Best regards,
Jacek Anaszewski
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