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>

3 files changed, 41 insertions, 5 deletions

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index a62e8d07b06a..13986b7b9a61 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/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,
diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
index 02c0ecffa804..22aff07c1995 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
+++ b/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);
diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
index 1e24b3722ff1..cba3ffd88649 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;