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authorAndre Przywara <andre.przywara@arm.com>2019-11-19 12:03:31 +0000
committerSudeep Holla <sudeep.holla@arm.com>2019-11-25 17:43:51 +0000
commit39a1a8941b27c37f79508426e27a2ec29829d66c (patch)
treece1a01ad5396baa3c6d2ec952d51afe41aeaccdd /arch/arm64
parent577dd5de09906e37a407a4326d17e58f6051fa2d (diff)
downloadlinux-39a1a8941b27c37f79508426e27a2ec29829d66c.tar.bz2
arm64: dts: juno: Fix UART frequency
Older versions of the Juno *SoC* TRM [1] recommended that the UART clock source should be 7.2738 MHz, whereas the *system* TRM [2] stated a more correct value of 7.3728 MHz. Somehow the wrong value managed to end up in our DT. Doing a prime factorisation, a modulo divide by 115200 and trying to buy a 7.2738 MHz crystal at your favourite electronics dealer suggest that the old value was actually a typo. The actual UART clock is driven by a PLL, configured via a parameter in some board.txt file in the firmware, which reads 7.37 MHz (sic!). Fix this to correct the baud rate divisor calculation on the Juno board. [1] http://infocenter.arm.com/help/topic/com.arm.doc.ddi0515b.b/DDI0515B_b_juno_arm_development_platform_soc_trm.pdf [2] http://infocenter.arm.com/help/topic/com.arm.doc.100113_0000_07_en/arm_versatile_express_juno_development_platform_(v2m_juno)_technical_reference_manual_100113_0000_07_en.pdf Fixes: 71f867ec130e ("arm64: Add Juno board device tree.") Signed-off-by: Andre Przywara <andre.przywara@arm.com> Acked-by: Liviu Dudau <liviu.dudau@arm.com> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Diffstat (limited to 'arch/arm64')
-rw-r--r--arch/arm64/boot/dts/arm/juno-clocks.dtsi4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/arm64/boot/dts/arm/juno-clocks.dtsi b/arch/arm64/boot/dts/arm/juno-clocks.dtsi
index e5e265dfa902..2870b5eeb198 100644
--- a/arch/arm64/boot/dts/arm/juno-clocks.dtsi
+++ b/arch/arm64/boot/dts/arm/juno-clocks.dtsi
@@ -8,10 +8,10 @@
*/
/ {
/* SoC fixed clocks */
- soc_uartclk: refclk7273800hz {
+ soc_uartclk: refclk7372800hz {
compatible = "fixed-clock";
#clock-cells = <0>;
- clock-frequency = <7273800>;
+ clock-frequency = <7372800>;
clock-output-names = "juno:uartclk";
};