RE: [PATCH 4/5] ARM: dts: imxrt1050: remove mmc max-frequency property

Bough Chen
2022-10-18T03:01:53Z

> -----Original Message-----
> From: Giulio Benetti <giulio.benetti@benettiengineering.com>
> Sent: 2022年10月18日 7:56
> To: devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
> linux-kernel@vger.kernel.org; linux-clk@vger.kernel.org;
> linux-mmc@vger.kernel.org
> Cc: Stephen Boyd <sboyd@kernel.org>; Bough Chen <haibo.chen@nxp.com>;
> Adrian Hunter <adrian.hunter@intel.com>; Ulf Hansson
> <ulf.hansson@linaro.org>; Giulio Benetti
> <giulio.benetti@benettiengineering.com>
> Subject: [PATCH 4/5] ARM: dts: imxrt1050: remove mmc max-frequency
> property
>
> According to i.MXRT1050 Reference Manual usdhc supports up to 208Mhz clock

Please double check this. As I know, the i.MXRT1050 and i.MX6/7/8/9 series use the same usdhc IP, maybe include some small difference.
For the usdhc in i.MX6/7/8/9, I confirmed with IC team, the card clock output from usdhc can't be upper than 200MHz, otherwise maybe meet some stable related issue.
So here I think should change to like this:
max-frequency = <200000000>;

Best Regards
Haibo Chen

> so let's remove max-frequency property in the .dtsi base file and in case add
> that property in the board specific .dts file for a specific device connected to it.
>
> Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
> ---
> arch/arm/boot/dts/imxrt1050.dtsi | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/arch/arm/boot/dts/imxrt1050.dtsi
> b/arch/arm/boot/dts/imxrt1050.dtsi
> index 114465e4dde6..0b44cc4ce6ad 100644
> --- a/arch/arm/boot/dts/imxrt1050.dtsi
> +++ b/arch/arm/boot/dts/imxrt1050.dtsi
> @@ -93,7 +93,6 @@ usdhc1: mmc@402c0000 {
> bus-width = <4>;
> fsl,wp-controller;
> no-1-8-v;
> - max-frequency = <4000000>;
> fsl,tuning-start-tap = <20>;
> fsl,tuning-step = <2>;
> status = "disabled";
> --
> 2.34.1