On Thu, May 02, 2019 at 02:01:45PM +0200, Lucas Stach wrote:

Hi Daniel,

Am Donnerstag, den 02.05.2019, 11:33 +0100 schrieb Daniel Thompson:

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On 29/04/2019 16:29, Lucas Stach wrote:

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This way the backlight can be referenced through its device node and
enabling/disabling can be managed through the panel driver.

Is it possible to implement something similar to 
pwm_backlight_initial_power_state() to handle this?

I'm not aware of any protocol to the RAVE-SP that would allow to read
back the backlight state. AFAICS the backlight is implemented as a
unidirectional protocol.

That function does two things... one is read the current power state to
ensure meta-data is correctly up to date which cannot be replicated.
The other is to choose different behaviour depending on whether the
backlight is standalone or has a phandle link to another device.

Does the second part apply to the rave-sp?


Daniel.

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backlight drivers already suffer from too much diversity so I prefer 
things like this to align behaviour with the (fairly heavilyly used) PWM 
driver if possible.


Daniel.

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Signed-off-by: Lucas Stach <l.stach@pengutronix.de>

---
  drivers/video/backlight/rave-sp-backlight.c | 4 +---
  1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/video/backlight/rave-sp-backlight.c b/drivers/video/backlight/rave-sp-backlight.c
index 462f14a1b19d..d296bfcf4396 100644
--- a/drivers/video/backlight/rave-sp-backlight.c
+++ b/drivers/video/backlight/rave-sp-backlight.c

@@ -48,15 +48,13 @@ static int rave_sp_backlight_probe(struct platform_device *pdev)

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  	struct device *dev = &pdev->dev;
  	struct backlight_device *bd;

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-	bd = devm_backlight_device_register(dev, pdev->name, dev->parent,
+	bd = devm_backlight_device_register(dev, pdev->name, dev,
  					    dev_get_drvdata(dev->parent),
  					    &rave_sp_backlight_ops,
  					    &rave_sp_backlight_props);
  	if (IS_ERR(bd))
  		return PTR_ERR(bd);

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-	backlight_update_status(bd);

-

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  	return 0;

  }