On 20/07/17 09:06, Pavel Machek wrote:
> Hi!
>
>>> --- a/drivers/video/backlight/pwm_bl.c
>>> +++ b/drivers/video/backlight/pwm_bl.c
>>> @@ -10,6 +10,7 @@
>>> * published by the Free Software Foundation.
>>> */
>>> +#include <linux/delay.h>
>>> #include <linux/gpio/consumer.h>
>>> #include <linux/gpio.h>
>>> #include <linux/module.h>
>>> @@ -35,6 +36,7 @@ struct pwm_bl_data {
>>> struct gpio_desc *enable_gpio;
>>> unsigned int scale;
>>> bool legacy;
>>> + unsigned int pwm_delay[2];
>>
>> Two named members would be better here (eliminating the "magic" 0
>> and 1).
>
> My thought, too.
>
>>> @@ -56,6 +58,9 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness)
>>> pwm_enable(pb->pwm);
>>> + if (pb->pwm_delay[0])
>>> + usleep_range(pb->pwm_delay[0], pb->pwm_delay[0] * 2);
>
> Plus I'd just do the delay unconditionally :-).
... does this still apply if this code is switched to msleep()?
msleep() has no wait avoidance[1] and if lots of drivers are reckless
about sleeping for 10ms it soon starts to show up in the boot time
(especially optimized ones).
Daniel.
[1] As it happens I can't see that many early bail out paths in
usleep_range() either.
