Re: [PATCH] arm64: dts: imx8mq: disable DDRC node by default

[Martin Kepplinger <martink@posteo.de>]

Am Sonntag, dem 12.12.2021 um 20:15 +0100 schrieb Lucas Stach:
> Without a OPP table or a downstream TF-A running on the system the
> DDRC will
> fail to probe, as it has no means to scale the DRAM frequency in that
> case.
> This however will block the bus scaling driver to come up and this in
> turn
> prevents other devices that hook into the interconnect from probing.
> 
> If the DDRC is disabled, the interconnect driver will simply ignore
> it. As
> most systems don't want to scale the DRAM frequency, disable the node
> by
> default and only enable it on the systems that actually uses this
> capability and provides a valid OPP table in the DT.
> 
> Signed-off-by: Lucas Stach <dev@lynxeye.de>
> 

Acked-by: Martin Kepplinger <martin.kepplinger@puri.sm>

but I'd like to append a question to NXP who afaik implemented devfreq
depending on "downstream TF-A" for imx8m: How are your plans to add
support to mainline TF-A?

thank you!

                        martin


> ---
>  arch/arm64/boot/dts/freescale/imx8mq-evk.dts      | 1 +
>  arch/arm64/boot/dts/freescale/imx8mq-librem5.dtsi | 1 +
>  arch/arm64/boot/dts/freescale/imx8mq.dtsi         | 1 +
>  3 files changed, 3 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/freescale/imx8mq-evk.dts
> b/arch/arm64/boot/dts/freescale/imx8mq-evk.dts
> index b83df77195ec..e989a9e450ed 100644
> --- a/arch/arm64/boot/dts/freescale/imx8mq-evk.dts
> +++ b/arch/arm64/boot/dts/freescale/imx8mq-evk.dts
> @@ -122,6 +122,7 @@ &A53_3 {
>  };
>  
>  &ddrc {
> +       status = "okay";
>         operating-points-v2 = <&ddrc_opp_table>;
>  
>         ddrc_opp_table: opp-table {
> diff --git a/arch/arm64/boot/dts/freescale/imx8mq-librem5.dtsi
> b/arch/arm64/boot/dts/freescale/imx8mq-librem5.dtsi
> index 60d47c71499b..5c0e98c36f94 100644
> --- a/arch/arm64/boot/dts/freescale/imx8mq-librem5.dtsi
> +++ b/arch/arm64/boot/dts/freescale/imx8mq-librem5.dtsi
> @@ -238,6 +238,7 @@ &A53_3 {
>  };
>  
>  &ddrc {
> +       status = "okay";
>         operating-points-v2 = <&ddrc_opp_table>;
>  
>         ddrc_opp_table: opp-table {
> diff --git a/arch/arm64/boot/dts/freescale/imx8mq.dtsi
> b/arch/arm64/boot/dts/freescale/imx8mq.dtsi
> index 972766b67a15..f5af9765e239 100644
> --- a/arch/arm64/boot/dts/freescale/imx8mq.dtsi
> +++ b/arch/arm64/boot/dts/freescale/imx8mq.dtsi
> @@ -1554,6 +1554,7 @@ ddrc: memory-controller@3d400000 {
>                                  <&clk IMX8MQ_DRAM_PLL_OUT>,
>                                  <&clk IMX8MQ_CLK_DRAM_ALT>,
>                                  <&clk IMX8MQ_CLK_DRAM_APB>;
> +                       status = "disabled";
>                 };
>  
>                 ddr-pmu@3d800000 {



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