linux-kernel - [PATCH] cpufreq: arm_big_little: fix frequency check when bL switcher is active

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <1443807532.2845.25.camel@linaro.org>
Date:	Fri, 02 Oct 2015 18:38:52 +0100
From:	"Jon Medhurst (Tixy)" <tixy@...aro.org>
To:	Viresh Kumar <viresh.kumar@...aro.org>,
	Sudeep Holla <sudeep.holla@....com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Michael Turquette <mike.turquette@...aro.org>
Subject: [PATCH] cpufreq: arm_big_little: fix frequency check when bL
 switcher is active

The check for correct frequency being set in bL_cpufreq_set_rate is
broken when the big.LITTLE switcher is active, for two reasons.

1. The 'new_rate' variable gets overwritten before the test by the
code calculating the frequency of the old cluster.

2. The frequency returned by bL_cpufreq_get_rate will be the virtual
frequency, not the actual one the intended version of new_rate contains.

This means the function always returns an error causing an endless
stream of: "cpufreq: __target_index: Failed to change cpu frequency: -5"

As the comment for the test indicates that it is temporary and limited
lets not bother fixing it to work when the bL switcher is active and
instead just bypass the test in that case.

Fixes: 0a95e630b49a ("cpufreq: arm_big_little: check if the frequency is set correctly")

Signed-off-by: Jon Medhurst <tixy@...aro.org>
---
 drivers/cpufreq/arm_big_little.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpufreq/arm_big_little.c b/drivers/cpufreq/arm_big_little.c
index f1e42f8..71deddb 100644
--- a/drivers/cpufreq/arm_big_little.c
+++ b/drivers/cpufreq/arm_big_little.c
@@ -196,7 +196,7 @@ bL_cpufreq_set_rate(u32 cpu, u32 old_cluster, u32 new_cluster, u32 rate)
 	 * be reading only the cached value anyway. This needs to  be removed
 	 * once clk core is fixed.
 	 */
-	if (bL_cpufreq_get_rate(cpu) != new_rate)
+	if (!bLs && bL_cpufreq_get_rate(cpu) != new_rate)
 		return -EIO;
 	return 0;
 }
-- 
2.1.4



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/