Messages in this thread | | | Date | Fri, 21 Oct 2022 17:31:50 +0800 | Subject | Re: [PATCH 05/15] arm64: dts: imx8mp-evk: enable uart1/3 ports | From | Peng Fan <> |
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Hi Marco,
On 10/21/2022 5:09 PM, Marco Felsch wrote: > On 22-10-21, Peng Fan wrote: >> Hi Marco, >> >> On 10/20/2022 7:07 PM, Marco Felsch wrote: >>> Hi Peng, >>> >>> On 22-10-20, Peng Fan (OSS) wrote: >>>> From: Peng Fan <peng.fan@nxp.com> >>>> >>>> Enable uart1/3 ports for evk board. >>>> >>>> Signed-off-by: Peng Fan <peng.fan@nxp.com> >>>> --- >>>> arch/arm64/boot/dts/freescale/imx8mp-evk.dts | 36 ++++++++++++++++++++ >>>> 1 file changed, 36 insertions(+) >>>> >>>> diff --git a/arch/arm64/boot/dts/freescale/imx8mp-evk.dts b/arch/arm64/boot/dts/freescale/imx8mp-evk.dts >>>> index 2e29bb3c041c..366f709f8790 100644 >>>> --- a/arch/arm64/boot/dts/freescale/imx8mp-evk.dts >>>> +++ b/arch/arm64/boot/dts/freescale/imx8mp-evk.dts >>>> @@ -428,6 +428,15 @@ &snvs_pwrkey { >>>> status = "okay"; >>>> }; >>>> +&uart1 { /* BT */ >>>> + pinctrl-names = "default"; >>>> + pinctrl-0 = <&pinctrl_uart1>; >>>> + assigned-clocks = <&clk IMX8MP_CLK_UART1>; >>>> + assigned-clock-parents = <&clk IMX8MP_SYS_PLL1_80M>; >>> >>> I'm curious, what is the default parent and why is this wrong? For the >>> already exisiting uart2 we don't do that. Same applies for uart3. >> >> The default parent is OSC_24M. The uart2 is for console, so 24M is ok. >> As I recall, we met issue 24M not able to get higher baudrate. > > What did you mean by higher baudrate, is it everything > 115200? When > the console baudrates can be fullfilled with the PLL1_80M as well > wouldn't it be worth to fix the imx8mp.dtsi instead?
To console, we use 115200, 24M could fullfill it.
BaudRate = (clk / ref_clk_div) / (16 * (ubmr + 1) / (ubir + 1))
If you have 24M ref_clk, the max baudrate is 1.5M, with setting ubmr, ubir to 0, and ref clk divider to 1.
So more higher baudrate, 24M could not fulfill.
THanks, Peng.
> > Regards, > Marco
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