[PATCH v4 14/16] drm: bridge: analogix/dp: try force hpd after plug in lookup failed

[Yakir Yang <ykk@rock-chips.com>]

Some edp screen do not have hpd signal, so we can't just return
failed when hpd plug in detect failed.

This is an hardware property, so we need add a devicetree property
"analogix,need-force-hpd" to indicate this sutiation.

Signed-off-by: Yakir Yang <ykk@rock-chips.com>
---
Changes in v4: None
Changes in v3:
- Add "analogix,need-force-hpd" to indicate whether driver need foce
  hpd when hpd detect failed.

Changes in v2: None

 .../devicetree/bindings/drm/bridge/analogix_dp.txt |  4 ++-
 .../bindings/video/analogix_dp-rockchip.txt        |  1 +
 .../devicetree/bindings/video/exynos_dp.txt        |  1 +
 drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 36 +++++++++++++++++++---
 drivers/gpu/drm/bridge/analogix/analogix_dp_core.h |  2 ++
 drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c  |  9 ++++++
 6 files changed, 47 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/drm/bridge/analogix_dp.txt b/Documentation/devicetree/bindings/drm/bridge/analogix_dp.txt
index f54dc3e..c310367 100644
--- a/Documentation/devicetree/bindings/drm/bridge/analogix_dp.txt
+++ b/Documentation/devicetree/bindings/drm/bridge/analogix_dp.txt
@@ -22,6 +22,9 @@ Required properties for dp-controller:
 		from general PHY binding: Should be "dp".
 
 Optional properties for dp-controller:
+	-analogix,need-force-hpd:
+		Indicate driver need force hpd when hpd detect failed, this
+		is used for some eDP screen which don't have hpd signal.
 	-hpd-gpios:
 		Hotplug detect GPIO.
 		Indicates which GPIO should be used for hotplug detection
@@ -31,7 +34,6 @@ Optional properties for dp-controller:
 		* Documentation/devicetree/bindings/video/exynos_dp.txt
 		* Documentation/devicetree/bindings/video/analogix_dp-rockchip.txt
 
-
 [1]: Documentation/devicetree/bindings/media/video-interfaces.txt
 -------------------------------------------------------------------------------
 
diff --git a/Documentation/devicetree/bindings/video/analogix_dp-rockchip.txt b/Documentation/devicetree/bindings/video/analogix_dp-rockchip.txt
index 502483e..8b9ed7d 100644
--- a/Documentation/devicetree/bindings/video/analogix_dp-rockchip.txt
+++ b/Documentation/devicetree/bindings/video/analogix_dp-rockchip.txt
@@ -28,6 +28,7 @@ For the below properties, please refer to Analogix DP binding document:
 - phys (required)
 - phy-names (required)
 - hpd-gpios (optional)
+- analogix,need-force-hpd (optional)
 -------------------------------------------------------------------------------
 
 Example:
diff --git a/Documentation/devicetree/bindings/video/exynos_dp.txt b/Documentation/devicetree/bindings/video/exynos_dp.txt
index ea03b3a..4f06e80 100644
--- a/Documentation/devicetree/bindings/video/exynos_dp.txt
+++ b/Documentation/devicetree/bindings/video/exynos_dp.txt
@@ -41,6 +41,7 @@ For the below properties, please refer to Analogix DP binding document:
 	-phys (required)
 	-phy-names (required)
 	-hpd-gpios (optional)
+	-analogix,need-force-hpd (optional)
 	-video interfaces (optional)
 
 Deprecated properties for DisplayPort:
diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index f7227ec..e6b328a 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -63,15 +63,38 @@ static int analogix_dp_detect_hpd(struct analogix_dp_device *dp)
 {
 	int timeout_loop = 0;
 
-	while (analogix_dp_get_plug_in_status(dp) != 0) {
+	while (timeout_loop < DP_TIMEOUT_LOOP_COUNT) {
+		if (analogix_dp_get_plug_in_status(dp) == 0)
+			return 0;
+
 		timeout_loop++;
-		if (DP_TIMEOUT_LOOP_COUNT < timeout_loop) {
-			dev_err(dp->dev, "failed to get hpd plug status\n");
-			return -ETIMEDOUT;
-		}
 		usleep_range(10, 11);
 	}
 
+	/*
+	 * Some edp screen do not have hpd signal, so we can't just
+	 * return failed when hpd plug in detect failed, DT property
+	 * "need-force-hpd" would indicate whether driver need this.
+	 */
+	if (!dp->need_force_hpd)
+		return -ETIMEDOUT;
+
+	/*
+	 * The eDP TRM indicate that if HPD_STATUS(RO) is 0, AUX CH
+	 * will not work, so we need to give a force hpd action to
+	 * set HPD_STATUS manually.
+	 */
+	dev_dbg(dp->dev, "failed to get hpd plug status, try to force hpd\n");
+
+	analogix_dp_force_hpd(dp);
+
+	if (analogix_dp_get_plug_in_status(dp) != 0) {
+		dev_err(dp->dev, "failed to get hpd plug in status\n");
+		return -EINVAL;
+	}
+
+	dev_dbg(dp->dev, "success to get plug in status after force hpd\n");
+
 	return 0;
 }
 
@@ -1287,6 +1310,9 @@ int analogix_dp_bind(struct device *dev, struct drm_device *drm_dev,
 	if (IS_ERR(dp->reg_base))
 		return PTR_ERR(dp->reg_base);
 
+	dp->need_force_hpd =
+		of_property_read_bool(dev->of_node, "analogix,need-force-hpd");
+
 	dp->hpd_gpio = of_get_named_gpio(dev->of_node, "hpd-gpios", 0);
 	if (gpio_is_valid(dp->hpd_gpio))
 		dp->hpd_gpio = of_get_named_gpio(dev->of_node,
diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
index d8945e2..6960ab3 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
@@ -160,6 +160,7 @@ struct analogix_dp_device {
 	struct phy		*phy;
 	int			dpms_mode;
 	int			hpd_gpio;
+	bool                    need_force_hpd;
 
 	struct analogix_dp_plat_data *plat_data;
 };
@@ -180,6 +181,7 @@ void analogix_dp_set_analog_power_down(struct analogix_dp_device *dp,
 				       bool enable);
 void analogix_dp_init_analog_func(struct analogix_dp_device *dp);
 void analogix_dp_init_hpd(struct analogix_dp_device *dp);
+void analogix_dp_force_hpd(struct analogix_dp_device *dp);
 enum dp_irq_type analogix_dp_get_irq_type(struct analogix_dp_device *dp);
 void analogix_dp_clear_hotplug_interrupts(struct analogix_dp_device *dp);
 void analogix_dp_reset_aux(struct analogix_dp_device *dp);
diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
index 15346fe..3086afc 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
@@ -365,6 +365,15 @@ void analogix_dp_init_hpd(struct analogix_dp_device *dp)
 	writel(reg, dp->reg_base + ANALOGIX_DP_SYS_CTL_3);
 }
 
+void analogix_dp_force_hpd(struct analogix_dp_device *dp)
+{
+	u32 reg;
+
+	reg = readl(dp->reg_base + ANALOGIX_DP_SYS_CTL_3);
+	reg = (F_HPD | HPD_CTRL);
+	writel(reg, dp->reg_base + ANALOGIX_DP_SYS_CTL_3);
+}
+
 enum dp_irq_type analogix_dp_get_irq_type(struct analogix_dp_device *dp)
 {
 	u32 reg;
-- 
2.1.2