[PATCH v2] ARM: dts: i.MX8MM: describe feature controller

[Marco Felsch]

On 22-08-30, Ahmad Fatoum wrote:
> Hello Marco,
> 
> On 30.08.22 10:10, Marco Felsch wrote:
> > Hi Ahamd,
> > 
> > On 22-08-30, Ahmad Fatoum wrote:
> >> Now with i.MX8M feature controller driver support available, have the
> >> OCOTP provide feature control on the i.MX8MM to ensure the kernel DT
> >> does not cause Linux to access the VPU and its power domains,
> >> when barebox knows them to be unavailable.
> >>
> >> This is needed because the upstream kernel imx8mm.dtsi only
> >> describes the full-featured SoC, which can lead to hangs when
> >> instantiating drivers for hardware that's unavailable in a
> >> less-featureful variant of the SoC.
> >>
> >> Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
> >> ---
> >> v1 was RFC patch 10/10 of:
> >> https://lore.barebox.org/barebox/20220818051955.2088238-11-a.fatoum@pengutronix.de/T/#u
> >>
> >> Patches 01-08 are still applicable, this replaces the approach in v1
> >> with a standalone feature controller with having the OCOTP as feature
> >> controller, like is done for i.MX8MN in patch 08/10 of above referenced
> >> series.
> >> ---
> >>  arch/arm/dts/imx8mm.dtsi | 52 ++++++++++++++++++++++++++++++++++++++++
> >>  1 file changed, 52 insertions(+)
> >>
> >> diff --git a/arch/arm/dts/imx8mm.dtsi b/arch/arm/dts/imx8mm.dtsi
> >> index cdf212820594..1e81d03d6b84 100644
> >> --- a/arch/arm/dts/imx8mm.dtsi
> >> +++ b/arch/arm/dts/imx8mm.dtsi
> >> @@ -1,10 +1,18 @@
> >>  // SPDX-License-Identifier: (GPL-2.0+ OR MIT)
> >> +
> >> +#include <dt-bindings/features/imx8m.h>
> >> +
> >>  / {
> >>  	aliases {
> >>  		gpr.reboot_mode = &reboot_mode_gpr;
> >>  	};
> >>  };
> >>  
> >> +feat: &ocotp {
> >> +	#feature-cells = <1>;
> >> +	barebox,feature-controller;
> >> +};
> > 
> > Why not just appending the node like:
> > 
> > / {
> > 	aliases {
> > 		gpr.reboot_mode = &reboot_mode_gpr;
> > 	};
> > 
> > 	feat: ocotp {
> > 		#feature-cells = <1>;
> > 		barebox,feature-controller;
> > 	};
> > };
> 
> Yours adds a new /ocotp node while my patch gives the existing
> node pointed at by &ocotp an additional label and extends it.

This should extend the ocotp node as well or would it be a new node
due to the new label? To me it locked very strange, therefore I asked. I
never noticed that: "new_label: &old_label {}" is even possible.

Regards,
  Marco

> I prefer the additional label, because it gives us flexibility
> in future if upstream decides that there should be a dedicated
> feature controller. In that case we would only need to move
> the label instead of touching all references. see RFC patch 10/10
> referenced above.
> 
> Cheers,
> Ahmad
> 
> > 
> > Regards,
> >   Marco
> > 
> >> +
> >>  &pgc_otg1 {
> >>  	barebox,allow-dummy;
> >>  };
> >> @@ -24,3 +32,47 @@
> >>  		mode-serial = <0x00000010>, <0x40000000>;
> >>  	};
> >>  };
> >> +
> >> +&A53_1 {
> >> +	barebox,feature-gates = <&feat IMX8M_FEAT_CPU_DUAL>;
> >> +};
> >> +
> >> +&A53_2 {
> >> +	barebox,feature-gates = <&feat IMX8M_FEAT_CPU_QUAD>;
> >> +};
> >> +
> >> +&A53_3 {
> >> +	barebox,feature-gates = <&feat IMX8M_FEAT_CPU_QUAD>;
> >> +};
> >> +
> >> +&gpc {
> >> +	barebox,feature-gates = <&feat 0>;
> >> +};
> >> +
> >> +&vpu_g1 {
> >> +	barebox,feature-gates = <&feat IMX8M_FEAT_VPU>;
> >> +};
> >> +
> >> +&vpu_g2 {
> >> +	barebox,feature-gates = <&feat IMX8M_FEAT_VPU>;
> >> +};
> >> +
> >> +&vpu_blk_ctrl {
> >> +	barebox,feature-gates = <&feat IMX8M_FEAT_VPU>;
> >> +};
> >> +
> >> +&pgc_vpumix {
> >> +	barebox,feature-gates = <&feat IMX8M_FEAT_VPU>;
> >> +};
> >> +
> >> +&pgc_vpu_g1 {
> >> +	barebox,feature-gates = <&feat IMX8M_FEAT_VPU>;
> >> +};
> >> +
> >> +&pgc_vpu_g2 {
> >> +	barebox,feature-gates = <&feat IMX8M_FEAT_VPU>;
> >> +};
> >> +
> >> +&pgc_vpu_h1 {
> >> +	barebox,feature-gates = <&feat IMX8M_FEAT_VPU>;
> >> +};
> >> -- 
> >> 2.30.2
> >>
> >>
> >>
> > 
> 
> 
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