From: Andre Przywara andre.przywara@arm.com
[ Upstream commit 39a1a8941b27c37f79508426e27a2ec29829d66c ]
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_... [2] http://infocenter.arm.com/help/topic/com.arm.doc.100113_0000_07_en/arm_versa...
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 Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- arch/arm64/boot/dts/arm/juno-clocks.dtsi | 4 ++-- 1 file 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 e5e265d..2870b5e 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"; };