[v7 3/5] drm/panel-simple: Support for delays between GPIO & regulator

Rajeev Nandan
2021-06-19T10:41:25Z

Some panels datasheets may specify a delay between the enable GPIO and
the regulator. Support this in panel-simple.

Signed-off-by: Rajeev Nandan <rajeevny@codeaurora.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
---

(no changes since v6)

Changes in v4:
- New

Changes in v5:
- Update description (Douglas)
- Warn if "power_to_enable" or "disable_to_power_off" is non-zero and panel->enable_gpio
is NULL (Douglas)

Changes in v6:
- Update warning message to make it more meaningful. (Douglas)

drivers/gpu/drm/panel/panel-simple.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
index 26555ec..86e5a45 100644
--- a/drivers/gpu/drm/panel/panel-simple.c
+++ b/drivers/gpu/drm/panel/panel-simple.c
@@ -133,6 +133,22 @@ struct panel_desc {
unsigned int prepare_to_enable;

/**
+ * @delay.power_to_enable: Time for the power to enable the display on.
+ *
+ * The time (in milliseconds) to wait after powering up the display
+ * before asserting its enable pin.
+ */
+ unsigned int power_to_enable;
+
+ /**
+ * @delay.disable_to_power_off: Time for the disable to power the display off.
+ *
+ * The time (in milliseconds) to wait before powering off the display
+ * after deasserting its enable pin.
+ */
+ unsigned int disable_to_power_off;
+
+ /**
* @delay.enable: Time for the panel to display a valid frame.
*
* The time (in milliseconds) that it takes for the panel to
@@ -347,6 +363,10 @@ static int panel_simple_suspend(struct device *dev)
struct panel_simple *p = dev_get_drvdata(dev);

gpiod_set_value_cansleep(p->enable_gpio, 0);
+
+ if (p->desc->delay.disable_to_power_off)
+ msleep(p->desc->delay.disable_to_power_off);
+
regulator_disable(p->supply);
p->unprepared_time = ktime_get();

@@ -407,6 +427,9 @@ static int panel_simple_prepare_once(struct panel_simple *p)
return err;
}

+ if (p->desc->delay.power_to_enable)
+ msleep(p->desc->delay.power_to_enable);
+
gpiod_set_value_cansleep(p->enable_gpio, 1);

delay = p->desc->delay.prepare;
@@ -782,6 +805,11 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc,
break;
}

+ if (!panel->enable_gpio && desc->delay.disable_to_power_off)
+ dev_warn(dev, "Need a delay after disabling panel GPIO, but a GPIO wasn't provided\n");
+ if (!panel->enable_gpio && desc->delay.power_to_enable)
+ dev_warn(dev, "Need a delay before enabling panel GPIO, but a GPIO wasn't provided\n");
+
dev_set_drvdata(dev, panel);

/*
--
2.7.4