[Cc += devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org]

Hello Tomi,

On Wed, Dec 16, 2015 at 07:35:30PM +0200, Tomi Valkeinen wrote:

On 10/12/15 15:11, Uwe Kleine-König wrote:

quoted

From: Uwe Kleine-König <redacted>

Some displays have a reset input. To assert that the display is
functional the reset gpio must be deasserted.

Teach the driver to get and drive such a gpio accordingly.

Signed-off-by: Uwe Kleine-König <redacted>
---
 Documentation/devicetree/bindings/video/panel-dpi.txt | 1 +
 drivers/video/fbdev/omap2/displays-new/panel-dpi.c    | 7 +++++++
 2 files changed, 8 insertions(+)

DT changes should be posted to devicetree-u79uwXL29TaiAVqoAR/hOA@public.gmane.org And, I think,
the binding document changes are usually as a separate patch.

Right for devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, but separate patches for bindings
is news to me. Anyhow, I can split this off if you prefer.

quoted

diff --git a/Documentation/devicetree/bindings/video/panel-dpi.txt b/Documentation/devicetree/bindings/video/panel-dpi.txt
index a40180b05bab..1a1d8f6f884f 100644
--- a/Documentation/devicetree/bindings/video/panel-dpi.txt
+++ b/Documentation/devicetree/bindings/video/panel-dpi.txt

@@ -7,6 +7,7 @@ Required properties:
 Optional properties:
 - label: a symbolic name for the panel
 - enable-gpios: panel enable gpio
+- reset-gpios: GPIO to control the RESET pin
 
 Required nodes:
 - "panel-timing" containing video timings

diff --git a/drivers/video/fbdev/omap2/displays-new/panel-dpi.c b/drivers/video/fbdev/omap2/displays-new/panel-dpi.c
index 1216341a0d19..7e2f9e0813dc 100644
--- a/drivers/video/fbdev/omap2/displays-new/panel-dpi.c
+++ b/drivers/video/fbdev/omap2/displays-new/panel-dpi.c

@@ -32,6 +32,7 @@ struct panel_drv_data {
 	int backlight_gpio;
 
 	struct gpio_desc *enable_gpio;
+	struct gpio_desc *reset_gpio;
 };
 
 #define to_panel_data(p) container_of(p, struct panel_drv_data, dssdev)

@@ -83,6 +84,7 @@ static int panel_dpi_enable(struct omap_dss_device *dssdev)
 	if (r)
 		return r;
 
+	gpiod_set_value_cansleep(ddata->reset_gpio, 0);
 	gpiod_set_value_cansleep(ddata->enable_gpio, 1);
 
 	if (gpio_is_valid(ddata->backlight_gpio))

@@ -211,6 +213,11 @@ static int panel_dpi_probe_of(struct platform_device *pdev)
 	if (IS_ERR(ddata->enable_gpio))
 		return PTR_ERR(ddata->enable_gpio);
 
+	ddata->reset_gpio = devm_gpiod_get_optional(&pdev->dev,
+						    "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(ddata->reset_gpio))
+		return PTR_ERR(ddata->reset_gpio);
+
 	ddata->backlight_gpio = -ENOENT;
 
 	r = of_get_display_timing(node, "panel-timing", &timing);

This looks a bit odd to me. This only ever sets the reset gpio to 0, on
panel enable. If we never toggle the reset, it could be set to 0 at
probe time, right?

Reset is a bit tricky. I've seen panels where you have to have only a
short reset pulse (reset high, wait a short time, reset low). If you
leave the reset high, the panel draws extra power.

So I think the best we can do in a generic way is just to ensure the
reset is not asserted.

Good idea, will implement this in v2.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
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