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Commit 6b6b86c9 authored by Osvaldo Banuelos's avatar Osvaldo Banuelos
Browse files

clk: msm: clock-debug: acquire prepare lock during measurement 



If the rate of the clock being measured changes at the same
time clock_debug_measure_get() is called, there can be a
miscalculation of the value of the divider between the
measurement circuitry and clock output. Acquiring the prepare
lock fixes the race since it prevents clock rate changes during
measurement.

CRs-Fixed: 1109789
Change-Id: I51050379a45a51c22109a06bc4758d767f361da1
Signed-off-by: default avatarOsvaldo Banuelos <osvaldob@codeaurora.org>
parent 3162449f

drivers/clk/msm/clock-debug.c

+4 −1
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2007 Google, Inc.

 * Copyright (c) 2007-2014, 2016, The Linux Foundation. All rights reserved.

 * Copyright (c) 2007-2014, 2016-2017, The Linux Foundation. All rights

 * reserved.

 *

 * This software is licensed under the terms of the GNU General Public

 * License version 2, as published by the Free Software Foundation, and
@@ -77,6 +78,7 @@ static int clock_debug_measure_get(void *data, u64 *val) 
	else

		is_hw_gated = 0;



	mutex_lock(&clock->prepare_lock);

	ret = clk_set_parent(measure, clock);

	if (!ret) {

		/*
@@ -107,6 +109,7 @@ static int clock_debug_measure_get(void *data, u64 *val) 
	 */

	meas_rate = clk_get_rate(clock);

	sw_rate = clk_get_rate(measure->parent);

	mutex_unlock(&clock->prepare_lock);

	if (sw_rate && meas_rate >= (sw_rate * 2))

		*val *= DIV_ROUND_CLOSEST(meas_rate, sw_rate);