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From: Frieder Schrempf <frieder.schrempf@kontron.de>
To: Shawn Guo <shawnguo@kernel.org>, Frieder Schrempf <frieder@fris.de>
Cc: devicetree@vger.kernel.org, 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>,
	stable@vger.kernel.org, Fabio Estevam <festevam@gmail.com>,
	NXP Linux Team <linux-imx@nxp.com>,
	Pengutronix Kernel Team <kernel@pengutronix.de>
Subject: Re: [PATCH 5/8] arm64: dts: imx8mm-kontron: Fix CAN SPI clock frequency
Date: Tue, 5 Oct 2021 19:17:13 +0200	[thread overview]
Message-ID: <37c1845d-9323-3187-ed0b-b9795758649d@kontron.de> (raw)
In-Reply-To: <20211005071230.GC20743@dragon>

On 05.10.21 09:12, Shawn Guo wrote:
> On Thu, Sep 30, 2021 at 05:56:28PM +0200, Frieder Schrempf wrote:
>> 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.
> 
> Could you share some testing result of this change?

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: 21c4f45b335f ("arm64: dts: Add the Kontron i.MX8M Mini SoMs and baseboards")
> 
> It's really an optimization rather than fix, isn't it?

It removes the arbitrarily low limit on the SPI frequency, that was
caused by a typo in the original dts. As the usage of the CAN bus is
seriously affected by this I would consider it a fix. But if you think
otherwise, feel free to remove the Fixes tag.

> 
> Shawn
> 
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
>> ---
>>  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 f2c8ccefd1bf..dbf11e03ecce 100644
>> --- a/arch/arm64/boot/dts/freescale/imx8mm-kontron-n801x-s.dts
>> +++ b/arch/arm64/boot/dts/freescale/imx8mm-kontron-n801x-s.dts
>> @@ -98,7 +98,7 @@ 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
>>

WARNING: multiple messages have this Message-ID (diff)
From: Frieder Schrempf <frieder.schrempf@kontron.de>
To: Shawn Guo <shawnguo@kernel.org>, Frieder Schrempf <frieder@fris.de>
Cc: devicetree@vger.kernel.org, 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>,
	stable@vger.kernel.org, Fabio Estevam <festevam@gmail.com>,
	NXP Linux Team <linux-imx@nxp.com>,
	Pengutronix Kernel Team <kernel@pengutronix.de>
Subject: Re: [PATCH 5/8] arm64: dts: imx8mm-kontron: Fix CAN SPI clock frequency
Date: Tue, 5 Oct 2021 19:17:13 +0200	[thread overview]
Message-ID: <37c1845d-9323-3187-ed0b-b9795758649d@kontron.de> (raw)
In-Reply-To: <20211005071230.GC20743@dragon>

On 05.10.21 09:12, Shawn Guo wrote:
> On Thu, Sep 30, 2021 at 05:56:28PM +0200, Frieder Schrempf wrote:
>> 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.
> 
> Could you share some testing result of this change?

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: 21c4f45b335f ("arm64: dts: Add the Kontron i.MX8M Mini SoMs and baseboards")
> 
> It's really an optimization rather than fix, isn't it?

It removes the arbitrarily low limit on the SPI frequency, that was
caused by a typo in the original dts. As the usage of the CAN bus is
seriously affected by this I would consider it a fix. But if you think
otherwise, feel free to remove the Fixes tag.

> 
> Shawn
> 
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
>> ---
>>  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 f2c8ccefd1bf..dbf11e03ecce 100644
>> --- a/arch/arm64/boot/dts/freescale/imx8mm-kontron-n801x-s.dts
>> +++ b/arch/arm64/boot/dts/freescale/imx8mm-kontron-n801x-s.dts
>> @@ -98,7 +98,7 @@ 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
>>

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  reply	other threads:[~2021-10-05 17:17 UTC|newest]

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-30 15:56 [PATCH 0/8] Devicetree fixes and additions for Kontron SL/BL i.MX8MM boards Frieder Schrempf
2021-09-30 15:56 ` Frieder Schrempf
2021-09-30 15:56 ` [PATCH 1/8] arm64: dts: imx8mm-kontron: Add support for ultra high speed modes on SD card Frieder Schrempf
2021-09-30 15:56   ` Frieder Schrempf
2021-10-05  6:45   ` Shawn Guo
2021-10-05  6:45     ` Shawn Guo
2021-10-15 10:44     ` Frieder Schrempf
2021-10-15 10:44       ` Frieder Schrempf
2021-09-30 15:56 ` [PATCH 2/8] arm64: dts: imx8mm-kontron: Make sure SOC and DRAM supply voltages are correct Frieder Schrempf
2021-09-30 15:56   ` Frieder Schrempf
2021-09-30 16:02   ` Frieder Schrempf
2021-09-30 16:02     ` Frieder Schrempf
2021-10-05  6:49     ` Shawn Guo
2021-10-05  6:49       ` Shawn Guo
2021-10-05  6:53   ` Shawn Guo
2021-10-05  6:53     ` Shawn Guo
2021-10-05 13:10     ` Frieder Schrempf
2021-10-05 13:10       ` Frieder Schrempf
2021-10-15  3:51       ` Shawn Guo
2021-10-15  3:51         ` Shawn Guo
2021-09-30 15:56 ` [PATCH 3/8] arm64: dts: imx8mm-kontron: Set VDD_SNVS to 800 mV Frieder Schrempf
2021-09-30 15:56   ` Frieder Schrempf
2021-10-05  6:56   ` Shawn Guo
2021-10-05  6:56     ` Shawn Guo
2021-10-05 13:14     ` Frieder Schrempf
2021-10-05 13:14       ` Frieder Schrempf
2021-10-15  4:04       ` Shawn Guo
2021-10-15  4:04         ` Shawn Guo
2021-09-30 15:56 ` [PATCH 4/8] arm64: dts: imx8mm-kontron: Fix reg_rst_eth2 and reg_vdd_5v regulators Frieder Schrempf
2021-09-30 15:56   ` Frieder Schrempf
2021-10-05  7:09   ` Shawn Guo
2021-10-05  7:09     ` Shawn Guo
2021-10-05 17:06     ` Frieder Schrempf
2021-10-05 17:06       ` Frieder Schrempf
2021-10-15  4:09       ` Shawn Guo
2021-10-15  4:09         ` Shawn Guo
2021-10-15 11:32         ` Frieder Schrempf
2021-10-15 11:32           ` Frieder Schrempf
2021-09-30 15:56 ` [PATCH 5/8] arm64: dts: imx8mm-kontron: Fix CAN SPI clock frequency Frieder Schrempf
2021-09-30 15:56   ` Frieder Schrempf
2021-10-05  7:12   ` Shawn Guo
2021-10-05  7:12     ` Shawn Guo
2021-10-05 17:17     ` Frieder Schrempf [this message]
2021-10-05 17:17       ` Frieder Schrempf
2021-10-15  4:12       ` Shawn Guo
2021-10-15  4:12         ` Shawn Guo
2021-09-30 15:56 ` [PATCH 6/8] arm64: dts: imx8mm-kontron: Fix connection type for VSC8531 RGMII PHY Frieder Schrempf
2021-10-02 18:14   ` Heiko Thiery
2021-10-02 18:08   ` Heiko Thiery
2021-10-05  7:20   ` Shawn Guo
2021-10-05  7:20     ` Shawn Guo
2021-09-30 15:56 ` [PATCH 7/8] arm64: dts: imx8mm-kontron: Fix reset delays for ethernet PHY Frieder Schrempf
2021-09-30 15:56   ` Frieder Schrempf
2021-09-30 15:56 ` [PATCH 8/8] arm64: dts: imx8mm-kontron: Leave reg_vdd_arm always powered on Frieder Schrempf
2021-09-30 15:56   ` Frieder Schrempf
2021-09-30 18:52   ` Heiko Thiery
2021-09-30 18:52     ` Heiko Thiery
2021-10-05  7:27   ` Shawn Guo
2021-10-05  7:27     ` Shawn Guo

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