drm/bridge: it6505: fix HDCP CTS KSV list wait timer

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 <[email protected]>
Reviewed-by: AngeloGioacchino Del Regno <[email protected]>
Signed-off-by: Dmitry Baryshkov <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/20241230-v7-upstream-v7-9-e0fdd4844703@ite.corp-partner.google.com

Author: Hermes Wu

drivers/gpu/drm/bridge/ite-it6505.c

@@ -2096,12 +2096,13 @@ 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;
 
@@ -2110,13 +2111,12 @@ 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);