Re: [PATCH v3 1/3] leds: rgb: leds-qcom-lpg: Fix pwm resolution max for normal PWMs

[Sebastian Reichel]

Hi,

On Mon, Mar 03, 2025 at 01:52:50PM +0200, Abel Vesa wrote:
> Ideally, the requested duty cycle should never translate to a PWM
> value higher than the selected resolution (PWM size), but currently the
> best matched period is never reported back to the PWM consumer, so the
> consumer will still be using the requested period which is higher than
> the best matched one. This will result in PWM consumer requesting
> duty cycle values higher than the allowed PWM value.
> 
> In case of normal PWMs (non Hi-Res), the current implementation is
> capping the PWM value at a 9-bit resolution, even when the 6-bit
> resolution is selected.
> 
> Fix the issue by capping the PWM value to the maximum value allowed by
> the selected resolution.
> 
> Fixes: 7a3350495d9a ("leds: rgb: leds-qcom-lpg: Add support for 6-bit PWM resolution")
> Suggested-by: Anjelique Melendez <anjelique.melendez@xxxxxxxxxxxxxxxx>
> Signed-off-by: Abel Vesa <abel.vesa@xxxxxxxxxx>
> ---

Reviewed-by: Sebastian Reichel <sre@xxxxxxxxxx>

Greetings,

-- Sebastian

>  drivers/leds/rgb/leds-qcom-lpg.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/leds/rgb/leds-qcom-lpg.c b/drivers/leds/rgb/leds-qcom-lpg.c
> index 4e5c56ded1f0412c9913670699e912b24f3408bd..4454fc6a38480b61916318dd170f3eddc32976d6 100644
> --- a/drivers/leds/rgb/leds-qcom-lpg.c
> +++ b/drivers/leds/rgb/leds-qcom-lpg.c
> @@ -533,7 +533,7 @@ static void lpg_calc_duty(struct lpg_channel *chan, uint64_t duty)
>  		max = LPG_RESOLUTION_15BIT - 1;
>  		clk_rate = lpg_clk_rates_hi_res[chan->clk_sel];
>  	} else {
> -		max = LPG_RESOLUTION_9BIT - 1;
> +		max = BIT(lpg_pwm_resolution[chan->pwm_resolution_sel]) - 1;
>  		clk_rate = lpg_clk_rates[chan->clk_sel];
>  	}
>  
> 
> -- 
> 2.34.1
>

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