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
"force-hpd" to indicate this sutiation.

Signed-off-by: Yakir Yang <y...@rock-chips.com>
Acked-by: Rob Herring <r...@kernel.org>
Tested-by: Javier Martinez Canillas <jav...@osg.samsung.com>
---
Changes in v10.2:
- Add the ack from Rob Herring
- Fix the omissive "analogix,need-force-hpd" in Exynos DP document

Changes in v10.1:
- Rename the "analogix,need-force-hpd" to common 'force-hpd' (Rob)

Changes in v9: None
Changes in v8: None
Changes in v7: None
Changes in v6: None
Changes in v5: None
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

 .../bindings/display/bridge/analogix_dp.txt        |  4 ++-
 .../bindings/display/exynos/exynos_dp.txt          |  1 +
 .../display/rockchip/analogix_dp-rockchip.txt      |  1 +
 drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 35 ++++++++++++++++++----
 drivers/gpu/drm/bridge/analogix/analogix_dp_core.h |  2 ++
 drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c  |  9 ++++++
 6 files changed, 46 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/display/bridge/analogix_dp.txt 
b/Documentation/devicetree/bindings/display/bridge/analogix_dp.txt
index 7659a7a..4f2ba8c 100644
--- a/Documentation/devicetree/bindings/display/bridge/analogix_dp.txt
+++ b/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
 -------------------------------------------------------------------------------
 
diff --git a/Documentation/devicetree/bindings/display/exynos/exynos_dp.txt 
b/Documentation/devicetree/bindings/display/exynos/exynos_dp.txt
index 9905081..8800164 100644
--- a/Documentation/devicetree/bindings/display/exynos/exynos_dp.txt
+++ b/Documentation/devicetree/bindings/display/exynos/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)
+       -force-hpd (optional)
        -video interfaces (optional)
 
 Deprecated properties for DisplayPort:
diff --git 
a/Documentation/devicetree/bindings/display/rockchip/analogix_dp-rockchip.txt 
b/Documentation/devicetree/bindings/display/rockchip/analogix_dp-rockchip.txt
index dae86c4..187a708e 100644
--- 
a/Documentation/devicetree/bindings/display/rockchip/analogix_dp-rockchip.txt
+++ 
b/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:
diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c 
b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index a11504b..00aee44 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -59,15 +59,38 @@ 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
+        * "need-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;
 }
 
@@ -1246,6 +1269,8 @@ 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 e6f8243..07e147c 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                    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 21a3287..c7e2959 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;
-- 
1.9.1


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