linux-kernel - [PATCH AUTOSEL 6.6 16/17] drm/bridge: it6505: fix HDCP CTS KSV list wait timer

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Message-Id: <20250126145612.937679-16-sashal@kernel.org>
Date: Sun, 26 Jan 2025 09:56:11 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Hermes Wu <hermes.wu@....com.tw>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
	Sasha Levin <sashal@...nel.org>,
	andrzej.hajda@...el.com,
	neil.armstrong@...aro.org,
	rfoss@...nel.org,
	maarten.lankhorst@...ux.intel.com,
	mripard@...nel.org,
	tzimmermann@...e.de,
	airlied@...il.com,
	simona@...ll.ch,
	dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 6.6 16/17] drm/bridge: it6505: fix HDCP CTS KSV list wait timer

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

[ Upstream commit 9f9eef9ec1a2b57d95a86fe81df758e8253a7766 ]

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>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20241230-v7-upstream-v7-9-e0fdd4844703@ite.corp-partner.google.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 b23e6f663b18f..cedba2a76f014 100644
--- a/drivers/gpu/drm/bridge/ite-it6505.c
+++ b/drivers/gpu/drm/bridge/ite-it6505.c
@@ -2058,12 +2058,13 @@ 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;
 
@@ -2072,13 +2073,12 @@ 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);
-- 
2.39.5