drm/omap: panel-dpi: make (limited) use of a reset gpio

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.

Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/gpu/drm/omapdrm/displays/panel-dpi.c b/drivers/gpu/drm/omapdrm/displays/panel-dpi.c
index 7c2331be8d15..9dc1c2f1fbc1 100644
--- a/drivers/gpu/drm/omapdrm/displays/panel-dpi.c
+++ b/drivers/gpu/drm/omapdrm/displays/panel-dpi.c
@@ -213,6 +213,16 @@ static int panel_dpi_probe_of(struct platform_device *pdev)
 
         ddata->enable_gpio = gpio;
 
+        /*
+         * Many different panels are supported by this driver and there are
+         * probably very different needs for their reset pins in regards to
+         * timing and order relative to the enable gpio. So for now it's just
+         * ensured that the reset line isn't active.
+         */
+        gpio = devm_gpiod_get_optional(&pdev->dev, "reset", GPIOD_OUT_LOW);
+        if (IS_ERR(gpio))
+                return PTR_ERR(gpio);
+
         ddata->backlight_gpio = -ENOENT;
 
         r = of_get_display_timing(node, "panel-timing", &timing);