linux-kernel - [PATCH v8 2/3] drm/panel: startek-kd070fhfid015: add another init step

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Message-Id: <20231023-display-support-v8-2-c2dd7b0fb2bd@baylibre.com>
Date: Thu, 20 Mar 2025 09:48:46 +0100
From: Alexandre Mergnat <amergnat@...libre.com>
To: Catalin Marinas <catalin.marinas@....com>, 
 Will Deacon <will@...nel.org>, Neil Armstrong <neil.armstrong@...aro.org>, 
 Jessica Zhang <quic_jesszhan@...cinc.com>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Chun-Kuang Hu <chunkuang.hu@...nel.org>, 
 Philipp Zabel <p.zabel@...gutronix.de>, 
 Matthias Brugger <matthias.bgg@...il.com>, 
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 dri-devel@...ts.freedesktop.org, linux-mediatek@...ts.infradead.org, 
 Alexandre Mergnat <amergnat@...libre.com>
Subject: [PATCH v8 2/3] drm/panel: startek-kd070fhfid015: add another init
 step

Currently, the panel set power, set gpio and enable the display link
in stk_panel_prepare, pointed by drm_panel_funcs.prepare, called by
panel_bridge_atomic_pre_enable, pointed by
drm_bridge_funcs.atomic_pre_enable. According to the drm_bridge.h,
atomic_pre_enable must not enable the display link

Since the DSI driver is properly inited by the DRM, the panel try to
communicate with the panel before DSI is powered on.

To solve that, use stk_panel_enable to enable the display link because
it's called after the mtk_dsi_bridge_atomic_pre_enable which is power
on the DSI.

Signed-off-by: Alexandre Mergnat <amergnat@...libre.com>
---
 .../gpu/drm/panel/panel-startek-kd070fhfid015.c    | 25 +++++++++++++---------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-startek-kd070fhfid015.c b/drivers/gpu/drm/panel/panel-startek-kd070fhfid015.c
index c0c95355b7435..bc3c4038bf4f5 100644
--- a/drivers/gpu/drm/panel/panel-startek-kd070fhfid015.c
+++ b/drivers/gpu/drm/panel/panel-startek-kd070fhfid015.c
@@ -135,19 +135,9 @@ static int stk_panel_prepare(struct drm_panel *panel)
 	gpiod_set_value(stk->enable_gpio, 1);
 	mdelay(20);
 	gpiod_set_value(stk->reset_gpio, 1);
-	mdelay(10);
-	ret = stk_panel_init(stk);
-	if (ret < 0)
-		goto poweroff;
-
-	ret = stk_panel_on(stk);
-	if (ret < 0)
-		goto poweroff;
 
 	return 0;
 
-poweroff:
-	regulator_disable(stk->supplies[POWER].consumer);
 iovccoff:
 	regulator_disable(stk->supplies[IOVCC].consumer);
 	gpiod_set_value(stk->reset_gpio, 0);
@@ -156,6 +146,20 @@ static int stk_panel_prepare(struct drm_panel *panel)
 	return ret;
 }
 
+static int stk_panel_enable(struct drm_panel *panel)
+{
+	struct stk_panel *stk = to_stk_panel(panel);
+	int ret;
+
+	ret = stk_panel_init(stk);
+	if (ret < 0)
+		return ret;
+
+	ret = stk_panel_on(stk);
+
+	return ret;
+}
+
 static const struct drm_display_mode default_mode = {
 		.clock = 163204,
 		.hdisplay = 1200,
@@ -239,6 +243,7 @@ drm_panel_create_dsi_backlight(struct mipi_dsi_device *dsi)
 }
 
 static const struct drm_panel_funcs stk_panel_funcs = {
+	.enable = stk_panel_enable,
 	.unprepare = stk_panel_unprepare,
 	.prepare = stk_panel_prepare,
 	.get_modes = stk_panel_get_modes,

-- 
2.25.1