linux-kernel - [PATCH] clocksource/drivers/imx-tpm: exclude sched clock for ARM64

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: <20220105124304.3567629-1-peng.fan@oss.nxp.com>
Date:   Wed,  5 Jan 2022 20:43:04 +0800
From:   "Peng Fan (OSS)" <peng.fan@....nxp.com>
To:     daniel.lezcano@...aro.org, tglx@...utronix.de
Cc:     shawnguo@...nel.org, s.hauer@...gutronix.de, kernel@...gutronix.de,
        festevam@...il.com, linux-imx@....com,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Peng Fan <peng.fan@....com>
Subject: [PATCH] clocksource/drivers/imx-tpm: exclude sched clock for ARM64

From: Peng Fan <peng.fan@....com>

For ARM64 platform such as i.MX8ULP which has ARMv8 generic timer as sched
clock, which is much faster compared with tpm sched clock. Reading the
tpm count register in i.MX8ULP requires about 290ns, this is slow and
introduce scheduler latency. So exclude tpm sched clock for ARM64
platform.

Signed-off-by: Peng Fan <peng.fan@....com>
---
 drivers/clocksource/timer-imx-tpm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clocksource/timer-imx-tpm.c b/drivers/clocksource/timer-imx-tpm.c
index 2cdc077a39f5..2bd530b9adc4 100644
--- a/drivers/clocksource/timer-imx-tpm.c
+++ b/drivers/clocksource/timer-imx-tpm.c
@@ -150,10 +150,10 @@ static int __init tpm_clocksource_init(void)
 	tpm_delay_timer.read_current_timer = &tpm_read_current_timer;
 	tpm_delay_timer.freq = timer_of_rate(&to_tpm) >> 3;
 	register_current_timer_delay(&tpm_delay_timer);
-#endif
 
 	sched_clock_register(tpm_read_sched_clock, counter_width,
 			     timer_of_rate(&to_tpm) >> 3);
+#endif
 
 	return clocksource_mmio_init(timer_base + TPM_CNT,
 				     "imx-tpm",
-- 
2.25.1