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* [PATCH] arm64: dts: imx8mq: disable DDRC node by default
@ 2021-12-12 19:15 Lucas Stach
  2021-12-12 19:29 ` Fabio Estevam
                   ` (3 more replies)
  0 siblings, 4 replies; 6+ messages in thread
From: Lucas Stach @ 2021-12-12 19:15 UTC (permalink / raw)
  To: Shawn Guo
  Cc: Pengutronix Kernel Team, Fabio Estevam, NXP Linux Team,
	Guido Günther, Martin Kepplinger, linux-arm-kernel

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>
---
 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 {
-- 
2.31.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

^ permalink raw reply related	[flat|nested] 6+ messages in thread
* Re: [PATCH] arm64: dts: imx8mq: disable DDRC node by default
  2021-12-12 19:15 [PATCH] arm64: dts: imx8mq: disable DDRC node by default Lucas Stach
@ 2021-12-12 19:29 ` Fabio Estevam
  2021-12-13 14:36   ` Lucas Stach
  2021-12-13  8:31 ` Martin Kepplinger
                   ` (2 subsequent siblings)
  3 siblings, 1 reply; 6+ messages in thread
From: Fabio Estevam @ 2021-12-12 19:29 UTC (permalink / raw)
  To: Lucas Stach
  Cc: Shawn Guo, Pengutronix Kernel Team, NXP Linux Team,
	Guido Günther, Martin Kepplinger,
	moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE

Hi Lucas,

On Sun, Dec 12, 2021 at 4:16 PM Lucas Stach <dev@lynxeye.de> wrote:
>
> 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>

Reviewed-by: Fabio Estevam <festevam@gmail.com>

Should we do the same on imx8mm too?

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] arm64: dts: imx8mq: disable DDRC node by default
  2021-12-12 19:15 [PATCH] arm64: dts: imx8mq: disable DDRC node by default Lucas Stach
  2021-12-12 19:29 ` Fabio Estevam
@ 2021-12-13  8:31 ` Martin Kepplinger
  2021-12-13  8:34 ` Guido Günther
  2021-12-16  5:58 ` Shawn Guo
  3 siblings, 0 replies; 6+ messages in thread
From: Martin Kepplinger @ 2021-12-13  8:31 UTC (permalink / raw)
  To: Lucas Stach, Shawn Guo
  Cc: Pengutronix Kernel Team, Fabio Estevam, NXP Linux Team,
	Guido Günther, linux-arm-kernel

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 {



_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] arm64: dts: imx8mq: disable DDRC node by default
  2021-12-12 19:15 [PATCH] arm64: dts: imx8mq: disable DDRC node by default Lucas Stach
  2021-12-12 19:29 ` Fabio Estevam
  2021-12-13  8:31 ` Martin Kepplinger
@ 2021-12-13  8:34 ` Guido Günther
  2021-12-16  5:58 ` Shawn Guo
  3 siblings, 0 replies; 6+ messages in thread
From: Guido Günther @ 2021-12-13  8:34 UTC (permalink / raw)
  To: Lucas Stach
  Cc: Shawn Guo, Pengutronix Kernel Team, Fabio Estevam,
	NXP Linux Team, Martin Kepplinger, linux-arm-kernel

Hi,
On Sun, Dec 12, 2021 at 08:15:41PM +0100, Lucas Stach wrote:
> 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>
> ---
>  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 {

Reviewed-by: Guido Günther <agx@sigxcpu.org>

Cheers,
 -- Guido

> -- 
> 2.31.1
> 

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] arm64: dts: imx8mq: disable DDRC node by default
  2021-12-12 19:29 ` Fabio Estevam
@ 2021-12-13 14:36   ` Lucas Stach
  0 siblings, 0 replies; 6+ messages in thread
From: Lucas Stach @ 2021-12-13 14:36 UTC (permalink / raw)
  To: Fabio Estevam
  Cc: Shawn Guo, Pengutronix Kernel Team, NXP Linux Team,
	Guido Günther, Martin Kepplinger,
	moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE

Am Sonntag, dem 12.12.2021 um 16:29 -0300 schrieb Fabio Estevam:
> Hi Lucas,
> 
> On Sun, Dec 12, 2021 at 4:16 PM Lucas Stach <dev@lynxeye.de> wrote:
> > 
> > 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>
> 
> Reviewed-by: Fabio Estevam <festevam@gmail.com>
> 
> Should we do the same on imx8mm too?

Not sure, with the i.MX8MM there are a lot more systems that are
providing a valid OPP table. Also I don't see the interconnect being
hooked up to devices in the i.MX8MM DT, so a non-function interconnect
driver, will at least not block other devices as is the case with the
i.MX8MQ.

However, there still is the issue that all those systems those depend
on a downstream TF-A running on the system, as upstream TF-A has no
support for scaling the DDR frequency.

Regards,
Lucas


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] arm64: dts: imx8mq: disable DDRC node by default
  2021-12-12 19:15 [PATCH] arm64: dts: imx8mq: disable DDRC node by default Lucas Stach
                   ` (2 preceding siblings ...)
  2021-12-13  8:34 ` Guido Günther
@ 2021-12-16  5:58 ` Shawn Guo
  3 siblings, 0 replies; 6+ messages in thread
From: Shawn Guo @ 2021-12-16  5:58 UTC (permalink / raw)
  To: Lucas Stach
  Cc: Pengutronix Kernel Team, Fabio Estevam, NXP Linux Team,
	Guido Günther, Martin Kepplinger, linux-arm-kernel

On Sun, Dec 12, 2021 at 08:15:41PM +0100, Lucas Stach wrote:
> 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>
> ---
>  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";

Please move it to end of property list.

Shawn

>  	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 {
> -- 
> 2.31.1
> 

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2021-12-16  5:59 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-12-12 19:15 [PATCH] arm64: dts: imx8mq: disable DDRC node by default Lucas Stach
2021-12-12 19:29 ` Fabio Estevam
2021-12-13 14:36   ` Lucas Stach
2021-12-13  8:31 ` Martin Kepplinger
2021-12-13  8:34 ` Guido Günther
2021-12-16  5:58 ` Shawn Guo

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