linux-kernel - [PATCH v2 2/2] drm: bridge: cdns-mhdp8546: Add support for no-hpd

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Message-ID: <20230405142440.191939-3-j-choudhary@ti.com>
Date:   Wed, 5 Apr 2023 19:54:40 +0530
From:   Jayesh Choudhary <j-choudhary@...com>
To:     <dri-devel@...ts.freedesktop.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <krzysztof.kozlowski@...aro.org>
CC:     <andrzej.hajda@...el.com>, <neil.armstrong@...aro.org>,
        <rfoss@...nel.org>, <Laurent.pinchart@...asonboard.com>,
        <jonas@...boo.se>, <jernej.skrabec@...il.com>, <airlied@...il.com>,
        <daniel@...ll.ch>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <sam@...nborg.org>,
        <jani.nikula@...el.com>, <tzimmermann@...e.de>,
        <javierm@...hat.com>, <ville.syrjala@...ux.intel.com>,
        <r-ravikumar@...com>, <lyude@...hat.com>,
        <alexander.deucher@....com>, <sjakhade@...ence.com>,
        <yamonkar@...ence.com>, <a-bhatia1@...com>,
        <tomi.valkeinen@...asonboard.com>, <j-choudhary@...com>
Subject: [PATCH v2 2/2] drm: bridge: cdns-mhdp8546: Add support for no-hpd

From: Rahul T R <r-ravikumar@...com>

In J721S2 EVMs DP0 hpd is not connected to correct
hpd pin on SOC, to handle such cases, Add support for
"no-hpd" property in the device tree node to disable
hpd

Also change the log level for dpcd read failuers to
debug, since framework retries 32 times for each read

Signed-off-by: Rahul T R <r-ravikumar@...com>
Signed-off-by: Jayesh Choudhary <j-choudhary@...com>
---
 .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 37 ++++++++++++++++---
 .../drm/bridge/cadence/cdns-mhdp8546-core.h   |  1 +
 2 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
index f6822dfa3805..e177794b069d 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
@@ -54,6 +54,8 @@
 #include "cdns-mhdp8546-hdcp.h"
 #include "cdns-mhdp8546-j721e.h"
 
+static int cdns_mhdp_update_link_status(struct cdns_mhdp_device *mhdp);
+
 static int cdns_mhdp_mailbox_read(struct cdns_mhdp_device *mhdp)
 {
 	int ret, empty;
@@ -749,7 +751,7 @@ static int cdns_mhdp_fw_activate(const struct firmware *fw,
 	 * MHDP_HW_STOPPED happens only due to driver removal when
 	 * bridge should already be detached.
 	 */
-	if (mhdp->bridge_attached)
+	if (mhdp->bridge_attached && !mhdp->no_hpd)
 		writel(~(u32)CDNS_APB_INT_MASK_SW_EVENT_INT,
 		       mhdp->regs + CDNS_APB_INT_MASK);
 
@@ -845,7 +847,7 @@ static ssize_t cdns_mhdp_transfer(struct drm_dp_aux *aux,
 		ret = cdns_mhdp_dpcd_read(mhdp, msg->address,
 					  msg->buffer, msg->size);
 		if (ret) {
-			dev_err(mhdp->dev,
+			dev_dbg(mhdp->dev,
 				"Failed to read DPCD addr %u\n",
 				msg->address);
 
@@ -1738,6 +1740,19 @@ static int cdns_mhdp_attach(struct drm_bridge *bridge,
 
 	spin_unlock(&mhdp->start_lock);
 
+	if (mhdp->no_hpd) {
+		ret = wait_event_timeout(mhdp->fw_load_wq,
+					 mhdp->hw_state == MHDP_HW_READY,
+					 msecs_to_jiffies(100));
+		if (ret == 0) {
+			dev_err(mhdp->dev, "%s: Timeout waiting for fw loading\n",
+				__func__);
+			return -ETIMEDOUT;
+		}
+
+		cdns_mhdp_update_link_status(mhdp);
+		return 0;
+	}
 	/* Enable SW event interrupts */
 	if (hw_ready)
 		writel(~(u32)CDNS_APB_INT_MASK_SW_EVENT_INT,
@@ -2256,7 +2271,16 @@ static int cdns_mhdp_update_link_status(struct cdns_mhdp_device *mhdp)
 
 	mutex_lock(&mhdp->link_mutex);
 
-	mhdp->plugged = cdns_mhdp_detect_hpd(mhdp, &hpd_pulse);
+	if (mhdp->no_hpd) {
+		ret = drm_dp_dpcd_read_link_status(&mhdp->aux, status);
+		hpd_pulse = false;
+		if (ret < 0)
+			mhdp->plugged = false;
+		else
+			mhdp->plugged = true;
+	} else {
+		mhdp->plugged = cdns_mhdp_detect_hpd(mhdp, &hpd_pulse);
+	}
 
 	if (!mhdp->plugged) {
 		cdns_mhdp_link_down(mhdp);
@@ -2451,6 +2475,8 @@ static int cdns_mhdp_probe(struct platform_device *pdev)
 	mhdp->aux.dev = dev;
 	mhdp->aux.transfer = cdns_mhdp_transfer;
 
+	mhdp->no_hpd = of_property_read_bool(dev->of_node, "cdns,no-hpd");
+
 	mhdp->regs = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(mhdp->regs)) {
 		dev_err(dev, "Failed to get memory resource\n");
@@ -2526,8 +2552,9 @@ static int cdns_mhdp_probe(struct platform_device *pdev)
 
 	mhdp->bridge.of_node = pdev->dev.of_node;
 	mhdp->bridge.funcs = &cdns_mhdp_bridge_funcs;
-	mhdp->bridge.ops = DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID |
-			   DRM_BRIDGE_OP_HPD;
+	mhdp->bridge.ops = DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID;
+	if (!mhdp->no_hpd)
+		mhdp->bridge.ops |= DRM_BRIDGE_OP_HPD;
 	mhdp->bridge.type = DRM_MODE_CONNECTOR_DisplayPort;
 	if (mhdp->info)
 		mhdp->bridge.timings = mhdp->info->timings;
diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
index bedddd510d17..6786ccb51387 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
@@ -388,6 +388,7 @@ struct cdns_mhdp_device {
 
 	bool link_up;
 	bool plugged;
+	bool no_hpd;
 
 	/*
 	 * "start_lock" protects the access to bridge_attached and
-- 
2.25.1