drm: bridge: analogix/dp: try force hpd after plug in lookup failed

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.
Acked-by: Rob Herring <robh@kernel.org>
Tested-by: Caesar Wang <wxt@rock-chips.com>
Tested-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Yakir Yang <ykk@rock-chips.com>

Documentation/devicetree/bindings/display/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:
+	-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/display/exynos/exynos_dp.txt
 		* Documentation/devicetree/bindings/video/analogix_dp-rockchip.txt
 
-
 [1]: Documentation/devicetree/bindings/media/video-interfaces.txt
 -------------------------------------------------------------------------------
 

Documentation/devicetree/bindings/display/exynos/exynos_dp.txt

@@ -56,6 +56,7 @@ For the below properties, please refer to Analogix DP binding document:
 	-phys (required)
 	-phy-names (required)
 	-hpd-gpios (optional)
+	 force-hpd (optional)
 
 Deprecated properties for DisplayPort:
 -interlaced:            deprecated prop that can parsed from drm_display_mode.

Documentation/devicetree/bindings/display/rockchip/analogix_dp-rockchip.txt

@@ -32,6 +32,7 @@ For the below properties, please refer to Analogix DP binding document:
 - phys (required)
 - phy-names (required)
 - hpd-gpios (optional)
+- force-hpd (optional)
 -------------------------------------------------------------------------------
 
 Example:

drivers/gpu/drm/bridge/analogix/analogix_dp_core.c

@@ -62,15 +62,38 @@ 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 (timeout_loop > DP_TIMEOUT_LOOP_COUNT) {
-			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
+	 * "force-hpd" would indicate whether driver need this.
+	 */
+	if (!dp->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;
 }
 
@@ -1291,6 +1314,8 @@ 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->force_hpd = of_property_read_bool(dev->of_node, "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,

drivers/gpu/drm/bridge/analogix/analogix_dp_core.h

@@ -154,6 +154,7 @@ struct analogix_dp_device {
 	struct phy		*phy;
 	int			dpms_mode;
 	int			hpd_gpio;
+	bool                    force_hpd;
 
 	struct analogix_dp_plat_data *plat_data;
 };
@@ -174,6 +175,7 @@ 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);

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;