linux-kernel - Re: [PATCH 3/4] backlight: pwm_bl: Set scale type for CIE 1931 curves

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Message-ID: <20190627154920.aucjtaguatd5yd4m@holly.lan>
Date:   Thu, 27 Jun 2019 16:49:20 +0100
From:   Daniel Thompson <daniel.thompson@...aro.org>
To:     Lee Jones <lee.jones@...aro.org>
Cc:     Matthias Kaehlcke <mka@...omium.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Jingoo Han <jingoohan1@...il.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        linux-pwm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Douglas Anderson <dianders@...omium.org>,
        Brian Norris <briannorris@...omium.org>,
        Pavel Machek <pavel@....cz>,
        Jacek Anaszewski <jacek.anaszewski@...il.com>
Subject: Re: [PATCH 3/4] backlight: pwm_bl: Set scale type for CIE 1931 curves

On Thu, Jun 27, 2019 at 10:24:53AM +0100, Lee Jones wrote:
> On Fri, 21 Jun 2019, Daniel Thompson wrote:
> 
> > On 13/06/2019 20:43, Matthias Kaehlcke wrote:
> > > For backlight curves calculated with the CIE 1931 algorithm set
> > > the brightness scale type property accordingly. This makes the
> > > scale type available to userspace via the 'scale' sysfs attribute.
> > > 
> > > Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
> > 
> > I'd like to keep discussion on patch 2 open a bit longer (it's not part of
> > the thread below patch 2 but Pavel had concerns about the sysfs interface)
> > so this ack won't really push things forward but FWIW:
> > 
> > Acked-by: Daniel Thompson <daniel.thompson@...aro.org>
> 
> Does this depend on patch 2, or is it orthogonal?

IIRC it depends on patch 2 (since that't what introduces props.scale ).


Daniel.

> 
> > > ---
> > >   drivers/video/backlight/pwm_bl.c | 5 ++++-
> > >   1 file changed, 4 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
> > > index fb45f866b923..f067fe7aa35d 100644
> > > --- a/drivers/video/backlight/pwm_bl.c
> > > +++ b/drivers/video/backlight/pwm_bl.c
> > > @@ -553,6 +553,8 @@ static int pwm_backlight_probe(struct platform_device *pdev)
> > >   		goto err_alloc;
> > >   	}
> > > +	memset(&props, 0, sizeof(struct backlight_properties));
> > > +
> > >   	if (data->levels) {
> > >   		/*
> > >   		 * For the DT case, only when brightness levels is defined
> > > @@ -591,6 +593,8 @@ static int pwm_backlight_probe(struct platform_device *pdev)
> > >   			pb->levels = data->levels;
> > >   		}
> > > +
> > > +		props.scale = BACKLIGHT_SCALE_CIE1931;
> > >   	} else {
> > >   		/*
> > >   		 * That only happens for the non-DT case, where platform data
> > > @@ -601,7 +605,6 @@ static int pwm_backlight_probe(struct platform_device *pdev)
> > >   	pb->lth_brightness = data->lth_brightness * (state.period / pb->scale);
> > > -	memset(&props, 0, sizeof(struct backlight_properties));
> > >   	props.type = BACKLIGHT_RAW;
> > >   	props.max_brightness = data->max_brightness;
> > >   	bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb,
> > > 
> > 
> 
> -- 
> Lee Jones [李琼斯]
> Linaro Services Technical Lead
> Linaro.org │ Open source software for ARM SoCs
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