linux-kernel - [RFC PATCH 7/8] drm: bridge: analogix_dp: try force hpd after plug in lookup failed

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Date:	Thu,  6 Aug 2015 09:24:18 -0500
From:	Yakir Yang <ykk@...k-chips.com>
To:	Heiko Stuebner <heiko@...ech.de>,
	Russell King <rmk+kernel@....linux.org.uk>,
	Fabio Estevam <fabio.estevam@...escale.com>,
	Jingoo Han <jingoohan1@...il.com>,
	Inki Dae <inki.dae@...sung.com>
Cc:	djkurtz@...gle.com, dianders@...gle.com,
	Takashi Iwai <tiwai@...e.de>,
	Andrzej Hajda <a.hajda@...sung.com>,
	Yakir Yang <ykk@...k-chips.com>,
	Thierry Reding <treding@...dia.com>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	David Airlie <airlied@...ux.ie>,
	Gustavo Padovan <gustavo.padovan@...labora.co.uk>,
	Seung-Woo Kim <sw0312.kim@...sung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	Kukjin Kim <kgene@...nel.org>,
	Ajay Kumar <ajaykumar.rs@...sung.com>,
	Joonyoung Shim <jy0922.shim@...sung.com>,
	Vincent Palatin <vpalatin@...omium.org>,
	Mark Yao <mark.yao@...k-chips.com>,
	Andy Yan <andy.yan@...k-chips.com>,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	linux-samsung-soc@...r.kernel.org,
	linux-rockchip@...ts.infradead.org,
	linux-arm-kernel@...ts.infradead.org
Subject: [RFC PATCH 7/8] 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.

Besides 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.

Signed-off-by: Yakir Yang <ykk@...k-chips.com>
---
 drivers/gpu/drm/bridge/analogix_dp_core.c | 28 +++++++++++++++++++++++-----
 drivers/gpu/drm/bridge/analogix_dp_core.h |  1 +
 drivers/gpu/drm/bridge/analogix_dp_reg.c  |  9 +++++++++
 3 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/bridge/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix_dp_core.c
index 28724d4..7e67f19 100644
--- a/drivers/gpu/drm/bridge/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix_dp_core.c
@@ -68,15 +68,33 @@ 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.
+	 *
+	 * Besides 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 -ETIMEDOUT;
+	}
+
+	dev_dbg(dp->dev, "success to get plug in status after force hpd\n");
+
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/bridge/analogix_dp_core.h b/drivers/gpu/drm/bridge/analogix_dp_core.h
index fe72695..43cec77 100644
--- a/drivers/gpu/drm/bridge/analogix_dp_core.h
+++ b/drivers/gpu/drm/bridge/analogix_dp_core.h
@@ -183,6 +183,7 @@ 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_dp_reg.c b/drivers/gpu/drm/bridge/analogix_dp_reg.c
index 4d6e08a..3fb215b 100644
--- a/drivers/gpu/drm/bridge/analogix_dp_reg.c
+++ b/drivers/gpu/drm/bridge/analogix_dp_reg.c
@@ -366,6 +366,15 @@ 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


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