linux-kernel - [PATCH v6 09/10] drm/bridge: it6505: fix HDCP CTS KSV list wait timer

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Message-Id: <20241016-upstream-v6-v6-9-4d93a0c46de1@ite.com.tw>
Date: Wed, 16 Oct 2024 15:54:21 +0800
From: Hermes Wu via B4 Relay <devnull+Hermes.wu.ite.com.tw@...nel.org>
To: Andrzej Hajda <andrzej.hajda@...el.com>, 
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, 
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>, 
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
 Pin-yen Lin <treapking@...omium.org>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 Kenneth Hung <Kenneth.hung@....com.tw>, Pet Weng <Pet.Weng@....com.tw>, 
 Hermes Wu <Hermes.wu@....com.tw>
Subject: [PATCH v6 09/10] drm/bridge: it6505: fix HDCP CTS KSV list wait
 timer

From: Hermes Wu <Hermes.wu@....com.tw>

HDCP must disabled encryption and restart authentication after
waiting KSV for 5s.
The original method uses a counter in a waitting loop that may
wait much longer than it is supposed to.
Use time_after() for KSV wait timeout.

Signed-off-by: Hermes Wu <Hermes.wu@....com.tw>
---
 drivers/gpu/drm/bridge/ite-it6505.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
index 439cca455ecf91b5f83b0add416db7f099f9a34d..4fc2147e9788501f0161180fc865072ab965ecbf 100644
--- a/drivers/gpu/drm/bridge/ite-it6505.c
+++ b/drivers/gpu/drm/bridge/ite-it6505.c
@@ -2095,12 +2095,13 @@ static void it6505_hdcp_wait_ksv_list(struct work_struct *work)
 	struct it6505 *it6505 = container_of(work, struct it6505,
 					     hdcp_wait_ksv_list);
 	struct device *dev = it6505->dev;
-	unsigned int timeout = 5000;
-	u8 bstatus = 0;
+	u8 bstatus;
 	bool ksv_list_check;
+	/* 1B-04 wait ksv list for 5s */
+	unsigned long timeout = jiffies +
+				msecs_to_jiffies(5000) + 1;
 
-	timeout /= 20;
-	while (timeout > 0) {
+	for (;;) {
 		if (!it6505_get_sink_hpd_status(it6505))
 			return;
 
@@ -2109,13 +2110,12 @@ static void it6505_hdcp_wait_ksv_list(struct work_struct *work)
 		if (bstatus & DP_BSTATUS_READY)
 			break;
 
-		msleep(20);
-		timeout--;
-	}
+		if (time_after(jiffies, timeout)) {
+			DRM_DEV_DEBUG_DRIVER(dev, "KSV list wait timeout");
+			goto timeout;
+		}
 
-	if (timeout == 0) {
-		DRM_DEV_DEBUG_DRIVER(dev, "timeout and ksv list wait failed");
-		goto timeout;
+		msleep(20);
 	}
 
 	ksv_list_check = it6505_hdcp_part2_ksvlist_check(it6505);

-- 
2.34.1