Messages in this thread | | | Date | Tue, 5 Oct 2021 19:17:13 +0200 | Subject | Re: [PATCH 5/8] arm64: dts: imx8mm-kontron: Fix CAN SPI clock frequency | From | Frieder Schrempf <> |
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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 = <®_vdd_3v3>; >> xceiver-supply = <®_vdd_5v>; >> }; >> -- >> 2.33.0 >>
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