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| author | Andre Przywara <andre.przywara@arm.com> | 2019-11-19 12:03:31 +0000 |
|---|---|---|
| committer | Sudeep Holla <sudeep.holla@arm.com> | 2019-11-25 17:43:51 +0000 |
| commit | 39a1a8941b27c37f79508426e27a2ec29829d66c (patch) | |
| tree | ce1a01ad5396baa3c6d2ec952d51afe41aeaccdd /arch | |
| parent | 577dd5de09906e37a407a4326d17e58f6051fa2d (diff) | |
| download | linux-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')
| -rw-r--r-- | arch/arm64/boot/dts/arm/juno-clocks.dtsi | 4 |
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"; }; |