# Re: \[PATCHv3 19/41\] OMAPDSS: panel-dpi: Add DT support

- From: Tomi Valkeinen \<hidden\>
- Date: 2014-04-24 09:52:42 
- List: linux-fbdev
- Page: https://ratatoskr.run/linux-fbdev/2014/04/8089415
- Thread: https://ratatoskr.run/linux-arm-kernel/2014/01/8084149/t.md

```text
On 18/04/14 18:51, Tony Lindgren wrote:

>> +	gpio = of_get_gpio(node, 0);
>> +	if (gpio_is_valid(gpio) || gpio == -ENOENT) {
>> +		ddata->enable_gpio = gpio;
>> +	} else {
>> +		dev_err(&pdev->dev, "failed to parse enable gpio\n");
>> +		return gpio;
>> +	}
> 
> We should set the GPIO polarity based on the OF_GPIO_ACTIVE_LOW like
> gpio_backlight_probe_dt is doing. 

Instead of doing it with the old gpio API, and checking the 'active'
flag everywhere, I think we can use the new gpiod API which handles the
polarity automatically.

I attached prototype patches (based on -rc2) for panel dpi using that
approach. It's a bit messier than I'd like, because for non-DT boot we
need to request the gpio using the old API, and then convert it to
gpio_desc. We can remove that code when all the boards use DT.

I've compiled tested this only, as I don't have DPI panels I could use.
I did try similar approach for TFP410, and it seemed to work fine.

 Tomi

```

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