linux-kernel - [PATCH] arm64: dts: qcom: msm8939: Add clock-frequency for broadcast timer

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Message-Id: <20231204-msm8939-timer-v1-1-a2486c625786@gerhold.net>
Date:   Mon, 04 Dec 2023 10:55:53 +0100
From:   Stephan Gerhold <stephan@...hold.net>
To:     Bjorn Andersson <andersson@...nel.org>
Cc:     Andy Gross <agross@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Shawn Guo <shawn.guo@...aro.org>,
        Benjamin Li <benl@...areup.com>,
        James Willcox <jwillcox@...areup.com>,
        Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
        Leo Yan <leo.yan@...aro.org>,
        Vincent Knecht <vincent.knecht@...loo.org>,
        Jun Nie <jun.nie@...aro.org>, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Stephan Gerhold <stephan@...hold.net>
Subject: [PATCH] arm64: dts: qcom: msm8939: Add clock-frequency for
 broadcast timer

Looks like not all firmware versions used for MSM8939 program the timer
frequency for both broadcast/MMIO timers, causing a WARNING at runtime:

WARNING: CPU: 0 PID: 0 at kernel/time/clockevents.c:38 cev_delta2ns+0x74/0x90
pc : cev_delta2ns+0x74/0x90
lr : clockevents_config.part.0+0x64/0x8c
Call trace:
 cev_delta2ns+0x74/0x90
 clockevents_config_and_register+0x20/0x34
 arch_timer_mem_of_init+0x374/0x534
 timer_probe+0x88/0x110
 time_init+0x14/0x4c
 start_kernel+0x2c0/0x640

Unfortunately there is no way to fix the firmware on most of these
devices since it's proprietary and signed. As a workaround, specify the
clock-frequency explicitly in the DT to fix the warning.

Fixes: 61550c6c156c ("arm64: dts: qcom: Add msm8939 SoC")
Reported-by: Vincent Knecht <vincent.knecht@...loo.org>
Signed-off-by: Stephan Gerhold <stephan@...hold.net>
---
 arch/arm64/boot/dts/qcom/msm8939.dtsi | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/msm8939.dtsi b/arch/arm64/boot/dts/qcom/msm8939.dtsi
index 95610a32750a..4ba115eecfd5 100644
--- a/arch/arm64/boot/dts/qcom/msm8939.dtsi
+++ b/arch/arm64/boot/dts/qcom/msm8939.dtsi
@@ -2195,6 +2195,8 @@ timer@...0000 {
 			#address-cells = <1>;
 			#size-cells = <1>;
 			ranges;
+			/* Necessary because firmware does not configure this correctly */
+			clock-frequency = <19200000>;
 
 			frame@...1000 {
 				reg = <0x0b121000 0x1000>,

---
base-commit: adcad44bd1c73a5264bff525e334e2f6fc01bb9b
change-id: 20231204-msm8939-timer-c8c218aa2440

Best regards,
-- 
Stephan Gerhold <stephan@...hold.net>