linux-kernel - [PATCH v3 1/3] drm/panel-edp: Add powered_on_to

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Message-ID: <20231214152817.2766280-2-treapking@chromium.org>
Date:   Thu, 14 Dec 2023 23:27:50 +0800
From:   Pin-yen Lin <treapking@...omium.org>
To:     Douglas Anderson <dianders@...omium.org>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Jessica Zhang <quic_jesszhan@...cinc.com>,
        Sam Ravnborg <sam@...nborg.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     Guenter Roeck <groeck@...omium.org>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Pin-yen Lin <treapking@...omium.org>
Subject: [PATCH v3 1/3] drm/panel-edp: Add powered_on_to_enable delay

Add the support of powered_on_to_enable delay as the minimum time that
needs to have passed between the panel powered on and enable may begin.

This delay is seen in BOE panels as the minimum delay of T3+T4+T5+T6+T8
in the eDP timing diagrams.

Signed-off-by: Pin-yen Lin <treapking@...omium.org>
Reviewed-by: Douglas Anderson <dianders@...omium.org>

---

Changes in v3:
- Collect review tag.

 drivers/gpu/drm/panel/panel-edp.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-edp.c b/drivers/gpu/drm/panel/panel-edp.c
index a0b6f69b916f..44acf9cacaf7 100644
--- a/drivers/gpu/drm/panel/panel-edp.c
+++ b/drivers/gpu/drm/panel/panel-edp.c
@@ -70,6 +70,21 @@ struct panel_delay {
 	 */
 	unsigned int hpd_absent;
 
+	/**
+	 * @powered_on_to_enable: Time between panel powered on and enable.
+	 *
+	 * The minimum time, in milliseconds, that needs to have passed
+	 * between when panel powered on and enable may begin.
+	 *
+	 * This is (T3+T4+T5+T6+T8)-min on eDP timing diagrams or after the
+	 * power supply enabled until we can turn the backlight on and see
+	 * valid data.
+	 *
+	 * This doesn't normally need to be set if timings are already met by
+	 * prepare_to_enable or enable.
+	 */
+	unsigned int powered_on_to_enable;
+
 	/**
 	 * @prepare_to_enable: Time between prepare and enable.
 	 *
@@ -216,6 +231,7 @@ struct panel_edp {
 	bool prepared;
 
 	ktime_t prepared_time;
+	ktime_t powered_on_time;
 	ktime_t unprepared_time;
 
 	const struct panel_desc *desc;
@@ -455,6 +471,8 @@ static int panel_edp_prepare_once(struct panel_edp *p)
 
 	gpiod_set_value_cansleep(p->enable_gpio, 1);
 
+	p->powered_on_time = ktime_get_boottime();
+
 	delay = p->desc->delay.hpd_reliable;
 	if (p->no_hpd)
 		delay = max(delay, p->desc->delay.hpd_absent);
@@ -579,6 +597,8 @@ static int panel_edp_enable(struct drm_panel *panel)
 
 	panel_edp_wait(p->prepared_time, p->desc->delay.prepare_to_enable);
 
+	panel_edp_wait(p->powered_on_time, p->desc->delay.powered_on_to_enable);
+
 	p->enabled = true;
 
 	return 0;
-- 
2.43.0.472.g3155946c3a-goog