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SubjectRe: [RFC v2 3/5] arm64: dts: imx8mq: Combine PCIE power domains
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Am Donnerstag, den 07.02.2019, 16:29 -0800 schrieb Andrey Smirnov:
> According to NXP's FAE feedback and a comment in ATF firmware, PCIE1
> and PCIE2 power domains can't really be used independently. Due to
> shared reset line both power domains have to be turned on at the same
> time. Account for that quirk by combining PCIE power domains into a
> single 'pgc_pcie' power domain.
>
> Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
> Cc: Shawn Guo <shawnguo@kernel.org>
> Cc: Fabio Estevam <fabio.estevam@nxp.com>
> Cc: Chris Healy <cphealy@gmail.com>
> Cc: Lucas Stach <l.stach@pengutronix.de>
> Cc: Leonard Crestez <leonard.crestez@nxp.com>
> Cc: "A.s. Dong" <aisheng.dong@nxp.com>
> Cc: Richard Zhu <hongxing.zhu@nxp.com>
> Cc: linux-imx@nxp.com
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org

Nit below, otherwise:

Reviewed-by: Lucas Stach <l.stach@pengutronix.de>

> ---
>  arch/arm64/boot/dts/freescale/imx8mq.dtsi | 21 ++++++++++++++++++++-
>  1 file changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/boot/dts/freescale/imx8mq.dtsi b/arch/arm64/boot/dts/freescale/imx8mq.dtsi
> index 50436bd393ed..89babc531380 100644
> --- a/arch/arm64/boot/dts/freescale/imx8mq.dtsi
> +++ b/arch/arm64/boot/dts/freescale/imx8mq.dtsi
> @@ -273,9 +273,28 @@
>   reg = <IMX8M_POWER_DOMAIN_MIPI>;
>   };
>  
> - pgc_pcie1: power-domain@1 {
> + /*
> +  * As per comment in ATF source code:
> +  *
> +  * PCIE1 and PCIE2 share the
> +  * same reset signal, if we
> +  * power down PCIE2, PCIE1
> +  * will be held in reset too.
> +  *
> +  * So instead of creating two
> +  * separate power domains for
> +  * PCIE1 and PCIE2. We create
> +  * a link between 1 and 10 and

1 and 10 is not something that directly shows up in the DTS, so I think
it could be confusing to the reader. I would just state that as "link
between both" or something to that tune.

> +  * use what was supposed to be
> +  * domain 1 as a shared PCIE
> +  * power domain powering both
> +  * PCIE1 and PCIE2 at the same
> +  * time
> +  */
> + pgc_pcie: power-domain@1 {
>   #power-domain-cells = <0>;
>   reg = <IMX8M_POWER_DOMAIN_PCIE1>;
> + power-domains = <&pgc_pcie2>;
>   };
>  
>   pgc_otg1: power-domain@2 {

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