drm/panel-simple: Support for delays between GPIO & regulator

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>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1624726268-14869-4-git-send-email-rajeevny@codeaurora.org

diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
index 6f233f2..5fc9802 100644 (file)
--- 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);
 
        /*