Hi Neil,
Le mercredi 05 juillet 2023 à 15:57 +0200, Neil Armstrong a écrit :
> On 03/07/2023 23:47, Paul Cercueil wrote:
> > Register a backlight device to be able to switch between all the
> > gamma
> > levels.
> >
> > Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> > ---
> > drivers/gpu/drm/panel/panel-samsung-ld9040.c | 40
> > ++++++++++++++++++++
> > 1 file changed, 40 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> > b/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> > index 7fd9444b42c5..b4f87d6244cb 100644
> > --- a/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> > +++ b/drivers/gpu/drm/panel/panel-samsung-ld9040.c
> > @@ -8,6 +8,7 @@
> > * Andrzej Hajda <a.hajda@xxxxxxxxxxx>
> > */
> >
> > +#include <linux/backlight.h>
> > #include <linux/delay.h>
> > #include <linux/gpio/consumer.h>
> > #include <linux/module.h>
> > @@ -311,8 +312,40 @@ static int ld9040_parse_dt(struct ld9040 *ctx)
> > return 0;
> > }
> >
> > +static int ld9040_bl_update_status(struct backlight_device *dev)
> > +{
> > + struct ld9040 *ctx = dev_get_drvdata(&dev->dev);
> > +
> > + ctx->brightness = dev->props.brightness;
> > + ld9040_brightness_set(ctx);
> > +
> > + return 0;
> > +}
> > +
> > +static int ld9040_bl_get_intensity(struct backlight_device *dev)
> > +{
> > + if (dev->props.fb_blank == FB_BLANK_UNBLANK &&
> > + dev->props.power == FB_BLANK_UNBLANK)
> > + return dev->props.brightness;
> > +
> > + return 0;
> > +}
>
> You can totally drop the _get_brightness.
The current behaviour is to return 0 when the framebuffer is blanked. A
few drivers do that so I thought it was the norm; and the backlight
core doesn't do that by default (and just uses dev->props.brightness).
It is not clear to me if that's the preferred behaviour. The
"backlight_get_brightness" function in backlight.h seems to suggest
that the current behaviour is correct, unless it is not supposed to be
used in the backlight_ops.get_brightness() callback. Then in that case
some other drivers get it wrong too.
Cheers,
-Paul
> Neil
>
> > +
> > +static const struct backlight_ops ld9040_bl_ops = {
> > + .get_brightness = ld9040_bl_get_intensity,
> > + .update_status = ld9040_bl_update_status,
> > +};
> > +
> > +static const struct backlight_properties ld9040_bl_props = {
> > + .type = BACKLIGHT_RAW,
> > + .scale = BACKLIGHT_SCALE_NON_LINEAR,
> > + .max_brightness = ARRAY_SIZE(ld9040_gammas) - 1,
> > + .brightness = ARRAY_SIZE(ld9040_gammas) - 1,
> > +};
> > +
> > static int ld9040_probe(struct spi_device *spi)
> > {
> > + struct backlight_device *bldev;
> > struct device *dev = &spi->dev;
> > struct ld9040 *ctx;
> > int ret;
> > @@ -354,6 +387,13 @@ static int ld9040_probe(struct spi_device
> > *spi)
> > drm_panel_init(&ctx->panel, dev, &ld9040_drm_funcs,
> > DRM_MODE_CONNECTOR_DPI);
> >
> > +
> > + bldev = devm_backlight_device_register(dev, dev_name(dev),
> > dev,
> > + ctx, &ld9040_bl_ops,
> > + &ld9040_bl_props);
> > + if (IS_ERR(bldev))
> > + return PTR_ERR(bldev);
> > +
> > drm_panel_add(&ctx->panel);
> >
> > return 0;
>
