On 26.02.2018 11:57, Jani Nikula wrote:
> On Thu, 22 Feb 2018, Daniel Thompson <daniel.thompson@xxxxxxxxxx> wrote:
>> On Thu, Feb 22, 2018 at 02:01:16PM +0200, Claudiu Beznea wrote:
>>> Add PWM mode to pwm_config() function. The drivers which uses pwm_config()
>>> were adapted to this change.
>>>
>>> Signed-off-by: Claudiu Beznea <claudiu.beznea@xxxxxxxxxxxxx>
>>> ---
>>> arch/arm/mach-s3c24xx/mach-rx1950.c | 11 +++++++++--
>>> drivers/bus/ts-nbus.c | 2 +-
>>> drivers/clk/clk-pwm.c | 3 ++-
>>> drivers/gpu/drm/i915/intel_panel.c | 17 ++++++++++++++---
>>> drivers/hwmon/pwm-fan.c | 2 +-
>>> drivers/input/misc/max77693-haptic.c | 2 +-
>>> drivers/input/misc/max8997_haptic.c | 6 +++++-
>>> drivers/leds/leds-pwm.c | 5 ++++-
>>> drivers/media/rc/ir-rx51.c | 5 ++++-
>>> drivers/media/rc/pwm-ir-tx.c | 5 ++++-
>>> drivers/video/backlight/lm3630a_bl.c | 4 +++-
>>> drivers/video/backlight/lp855x_bl.c | 4 +++-
>>> drivers/video/backlight/lp8788_bl.c | 5 ++++-
>>> drivers/video/backlight/pwm_bl.c | 11 +++++++++--
>>> drivers/video/fbdev/ssd1307fb.c | 3 ++-
>>> include/linux/pwm.h | 6 ++++--
>>> 16 files changed, 70 insertions(+), 21 deletions(-)
>>>
>>> diff --git a/drivers/video/backlight/lm3630a_bl.c b/drivers/video/backlight/lm3630a_bl.c
>>> index 2030a6b77a09..696fa25dafd2 100644
>>> --- a/drivers/video/backlight/lm3630a_bl.c
>>> +++ b/drivers/video/backlight/lm3630a_bl.c
>>> @@ -165,8 +165,10 @@ static void lm3630a_pwm_ctrl(struct lm3630a_chip *pchip, int br, int br_max)
>>> {
>>> unsigned int period = pchip->pdata->pwm_period;
>>> unsigned int duty = br * period / br_max;
>>> + struct pwm_caps caps = { };
>>>
>>> - pwm_config(pchip->pwmd, duty, period);
>>> + pwm_get_caps(pchip->pwmd->chip, pchip->pwmd, &caps);
>>> + pwm_config(pchip->pwmd, duty, period, BIT(ffs(caps.modes) - 1));
>>
>> Well... I admit I've only really looked at the patches that impact
>> backlight but dispersing this really odd looking bit twiddling
>> throughout the kernel doesn't strike me a great API design.
>>
>> IMHO callers should not be required to find the first set bit in
>> some specially crafted set of capability bits simply to get sane
>> default behaviour.
>
> Agreed. IMHO the regular use case becomes rather tedious, ugly, and
> error prone.
Using simply PWM_MODE(NORMAL) instead of BIT(ffs(caps.modes) - 1) would be OK
from your side?
Or, what about using a function like pwm_mode_first() to get the first supported
mode by PWM channel?
Or, would you prefer to solve this inside pwm_config() function, let's say, in
case an invalid mode is passed as argument, to let pwm_config() to choose the
first available PWM mode for PWM channel passed as argument?
Thank you,
Claudiu Beznea
>
> BR,
> Jani.
>
>
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