Hi Uwe On Tue, Sep 09, 2025 at 03:49:22PM +0200, Uwe Kleine-König wrote:
On Fri, Aug 01, 2025 at 08:32:20AM +0200, Uwe Kleine-König wrote:On Thu, Jul 31, 2025 at 10:47:18AM +0200, Michael Grzeschik wrote: > diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c > index 237d3d3f3bb1a..5924e0b9f01e7 100644 > --- a/drivers/video/backlight/pwm_bl.c > +++ b/drivers/video/backlight/pwm_bl.c > @@ -518,13 +518,6 @@ static int pwm_backlight_probe(struct platform_device *pdev) > if (!state.period && (data->pwm_period_ns > 0)) > state.period = data->pwm_period_ns; > > - ret = pwm_apply_might_sleep(pb->pwm, &state); > - if (ret) { > - dev_err_probe(&pdev->dev, ret, > - "failed to apply initial PWM state"); > - goto err_alloc; > - } > - > memset(&props, 0, sizeof(struct backlight_properties)); > > if (data->levels) { > @@ -582,6 +575,15 @@ static int pwm_backlight_probe(struct platform_device *pdev) > pb->lth_brightness = data->lth_brightness * (div_u64(state.period, > pb->scale)); > > + state.duty_cycle = compute_duty_cycle(pb, data->dft_brightness, &state); > + > + ret = pwm_apply_might_sleep(pb->pwm, &state); > + if (ret) { > + dev_err_probe(&pdev->dev, ret, > + "failed to apply initial PWM state"); > + goto err_alloc; > + } > +I wonder why the PWM is updated at all in .probe(). Wouldn't it be the natural thing to keep the PWM configured as it was (in its reset default state or how the bootloader set it up)? Orthogonal to your change, while looking at the driver I wondered about: bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb, &pwm_backlight_ops, &props); if (IS_ERR(bl)) { ret = dev_err_probe(&pdev->dev, PTR_ERR(bl), "failed to register backlight\n"); goto err_alloc; } if (data->dft_brightness > data->max_brightness) { dev_warn(&pdev->dev, "invalid default brightness level: %u, using %u\n", data->dft_brightness, data->max_brightness); data->dft_brightness = data->max_brightness; } bl->props.brightness = data->dft_brightness; bl->props.power = pwm_backlight_initial_power_state(pb); backlight_update_status(bl); Shoudn't setting data->dft_brightness, bl->props.brightness and bl->props.power better happen before backlight_device_register()? Also calling backlight_update_status() after backlight_device_register() seems wrong to me, I'd claim the backend driver shouldn't call that.Do you intend to work on this orthogonal feedback? If not, I'll put it on my todo list.
Oh, yes, the orthogonal feedback. Thanks for the reminder of this actually intended patch not being ready. I will work on this first. If you like, please take the opurtunity to fix the issue you found. Regards, Michael -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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