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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Andre Przywara <andre.przywara@arm.com>,
	Liviu Dudau <liviu.dudau@arm.com>,
	Sudeep Holla <sudeep.holla@arm.com>,
	Sasha Levin <sashal@kernel.org>,
	linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org
Subject: [PATCH AUTOSEL 4.14 364/371] arm64: dts: juno: Fix UART frequency
Date: Thu, 16 Jan 2020 12:23:56 -0500
Message-ID: <20200116172403.18149-307-sashal@kernel.org> (raw)
In-Reply-To: <20200116172403.18149-1-sashal@kernel.org>

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_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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 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";
 	};
 
-- 
2.20.1


  parent reply index

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200116172403.18149-1-sashal@kernel.org>
2020-01-16 17:19 ` [PATCH AUTOSEL 4.14 075/371] ARM: dts: lpc32xx: add required clocks property to keypad device node Sasha Levin
2020-01-16 17:19 ` [PATCH AUTOSEL 4.14 076/371] ARM: dts: lpc32xx: reparent keypad controller to SIC1 Sasha Levin
2020-01-16 17:19 ` [PATCH AUTOSEL 4.14 077/371] ARM: dts: lpc32xx: fix ARM PrimeCell LCD controller variant Sasha Levin
2020-01-16 17:19 ` [PATCH AUTOSEL 4.14 078/371] ARM: dts: lpc32xx: fix ARM PrimeCell LCD controller clocks property Sasha Levin
2020-01-16 17:19 ` [PATCH AUTOSEL 4.14 079/371] ARM: dts: lpc32xx: phy3250: fix SD card regulator voltage Sasha Levin
2020-01-16 17:20 ` [PATCH AUTOSEL 4.14 145/371] arm64: dts: allwinner: a64: Add missing PIO clocks Sasha Levin
2020-01-16 17:20 ` [PATCH AUTOSEL 4.14 167/371] ARM: dts: ls1021: Fix SGMII PCS link remaining down after PHY disconnect Sasha Levin
2020-01-16 17:21 ` [PATCH AUTOSEL 4.14 205/371] ARM: dts: sun8i-h3: Fix wifi in Beelink X2 DT Sasha Levin
2020-01-16 17:21 ` [PATCH AUTOSEL 4.14 207/371] arm64: dts: meson: libretech-cc: set eMMC as removable Sasha Levin
2020-01-16 17:22 ` [PATCH AUTOSEL 4.14 259/371] ARM: dts: stm32: add missing vdda-supply to adc on stm32h743i-eval Sasha Levin
2020-01-16 17:23 ` [PATCH AUTOSEL 4.14 308/371] of: mdio: Fix a signedness bug in of_phy_get_and_connect() Sasha Levin
2020-01-16 17:23 ` [PATCH AUTOSEL 4.14 335/371] arm64: dts: meson-gxl-s905x-khadas-vim: fix gpio-keys-polled node Sasha Levin
2020-01-16 17:23 ` [PATCH AUTOSEL 4.14 336/371] arm64: dts: apq8096-db820c: Increase load on l21 for SDCARD Sasha Levin
2020-01-16 17:23 ` Sasha Levin [this message]
2020-01-16 17:23 ` [PATCH AUTOSEL 4.14 367/371] Revert "arm64: dts: juno: add dma-ranges property" Sasha Levin

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