From: Simon Glass <sjg@chromium.org>
Date: Wed, 28 Aug 2024 01:44:27 +0000 (-0600)
Subject: x86: Sync up tsc_timer with Linux
X-Git-Url: http://git.dujemihanovic.xyz/html/static/%7B%7B%20.Permalink%20%7D%7D?a=commitdiff_plain;h=ecf31113f17817f5ab9263937270255b6d05cdf9;p=u-boot.git

x86: Sync up tsc_timer with Linux

Since we are using the code from Linux, update it to the newer version
in v6.11

Signed-off-by: Simon Glass <sjg@chromium.org>
---

diff --git a/drivers/timer/tsc_timer.c b/drivers/timer/tsc_timer.c
index 2f2c2f27b7..dd16ab320b 100644
--- a/drivers/timer/tsc_timer.c
+++ b/drivers/timer/tsc_timer.c
@@ -83,7 +83,7 @@ static unsigned long cpu_mhz_from_cpuid(void)
 	if (cpuid_eax(0) < 0x16)
 		return 0;
 
-	return cpuid_eax(0x16);
+	return cpuid_eax(0x15);
 }
 
 /*
@@ -299,10 +299,19 @@ static unsigned long __maybe_unused quick_pit_calibrate(void)
 			if (!pit_expect_msb(0xff-i, &delta, &d2))
 				break;
 
+			delta -= tsc;
+
+			/*
+			 * Extrapolate the error and fail fast if the error will
+			 * never be below 500 ppm.
+			 */
+			if (i == 1 &&
+			    d1 + d2 >= (delta * MAX_QUICK_PIT_ITERATIONS) >> 11)
+				return 0;
+
 			/*
 			 * Iterate until the error is less than 500 ppm
 			 */
-			delta -= tsc;
 			if (d1+d2 >= delta >> 11)
 				continue;