Hi Rob, Srinivas > Subject: [RFC 1/2] dt-bindings: imx-ocotp: Add fusable-node property
Do you have any comments about this patch? Thanks, Peng. > > Introduce fusable-node property for i.MX OCOTP driver. > The property will only be used by Firmware(eg. U-Boot) to runtime disable the > nodes. > > Take i.MX6ULL for example, there are several parts that only have limited > modules enabled controlled by OCOTP fuse. It is not flexible to provide > several > dts for the serval parts, instead we could provide one device tree and let > Firmware to runtime disable the device tree nodes for those modules that are > disable(fused). > > Signed-off-by: Peng Fan <peng....@nxp.com> > --- > > Currently NXP vendor use U-Boot to set status to disabled for devices that > could not function, > https://source.codeaurora.org/external/imx/uboot-imx/tree/arch/arm/mach > -imx/mx6/module_fuse.c?h=imx_v2018.03_4.14.98_2.0.0_ga#n149 > But this approach is will not work if kernel dts node path changed. > > There are two approaches to resolve: > > 1. This patch is to add a fusable-node property, and Firmware will parse > the property and read fuse to decide whether to disable or keeep enable > the nodes. > > 2. There is another approach is that add nvmem-cells for all nodes that > could be disabled(fused). Then in each linux driver to use nvmem > api to detect fused or not, or in linux driver common code to check > device functionable or not with nvmem API. > > > To make it easy to work, we choose [1] here. Please advise whether it is > acceptable, because the property is not used by linux driver in approach [1]. > Or you prefer [2] or please advise if any better solution. > > Thanks. > > Documentation/devicetree/bindings/nvmem/imx-ocotp.txt | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/Documentation/devicetree/bindings/nvmem/imx-ocotp.txt > b/Documentation/devicetree/bindings/nvmem/imx-ocotp.txt > index 7a999a135e56..e9a998588dbd 100644 > --- a/Documentation/devicetree/bindings/nvmem/imx-ocotp.txt > +++ b/Documentation/devicetree/bindings/nvmem/imx-ocotp.txt > @@ -21,6 +21,8 @@ Required properties: > > Optional properties: > - read-only: disable write access > +- fusable-node: array of phandles with reg base and bit offset, this > + property is used by Firmware to runtime disable nodes. > > Optional Child nodes: > > @@ -42,4 +44,7 @@ Example: > tempmon_temp_grade: temp-grade@20 { > reg = <0x20 4>; > }; > + > + fusable-node = <&usdhc1 0x10 4 > + &usdhc2 0x10 5>; > }; > -- > 2.16.4
