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From:   Frieder Schrempf <frieder@fris.de>
To:     devicetree@vger.kernel.org,
        Frieder Schrempf <frieder.schrempf@kontron.de>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Rob Herring <robh+dt@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Shawn Guo <shawnguo@kernel.org>
Cc:     stable@vger.kernel.org, Fabio Estevam <festevam@gmail.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        Pengutronix Kernel Team <kernel@pengutronix.de>
Subject: [PATCH v2 5/6] arm64: dts: imx8mm-kontron: Fix CAN SPI clock frequency
Date:   Fri, 15 Oct 2021 14:48:39 +0200
Message-Id: <20211015124841.28226-6-frieder@fris.de>
In-Reply-To: <20211015124841.28226-1-frieder@fris.de>
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From: Frieder Schrempf <frieder.schrempf@kontron.de>

The MCP2515 can be used with an SPI clock of up to 10 MHz. Set the
limit accordingly to prevent any performance issues caused by the
really low clock speed of 100 kHz.

This removes the arbitrarily low limit on the SPI frequency, that was
caused by a typo in the original dts.

Without this change, receiving CAN messages on the board beyond a
certain bitrate will cause overrun errors (see 'ip -det -stat link show
can0').

With this fix, receiving messages on the bus works without any overrun
errors for bitrates up to 1 MBit.

Fixes: 8668d8b2e67f ("arm64: dts: Add the Kontron i.MX8M Mini SoMs and baseboards")
Cc: stable@vger.kernel.org
Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
---
Changes in v2:
  * Fix the commit ref in the Fixes tag
  * Improve commit message
---
 arch/arm64/boot/dts/freescale/imx8mm-kontron-n801x-s.dts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/freescale/imx8mm-kontron-n801x-s.dts b/arch/arm64/boot/dts/freescale/imx8mm-kontron-n801x-s.dts
index a192a047f264..14263cd40daf 100644
--- a/arch/arm64/boot/dts/freescale/imx8mm-kontron-n801x-s.dts
+++ b/arch/arm64/boot/dts/freescale/imx8mm-kontron-n801x-s.dts
@@ -97,7 +97,7 @@ can0: can@0 {
 		clocks = <&osc_can>;
 		interrupt-parent = <&gpio4>;
 		interrupts = <28 IRQ_TYPE_EDGE_FALLING>;
-		spi-max-frequency = <100000>;
+		spi-max-frequency = <10000000>;
 		vdd-supply = <&reg_vdd_3v3>;
 		xceiver-supply = <&reg_vdd_5v>;
 	};
-- 
2.33.0