Hello, On Wed Jan 24, 2024 at 8:22 PM CET, Rob Herring wrote: > On Wed, Jan 24, 2024 at 11:40 AM Théo Lebrun <theo.lebrun@xxxxxxxxxxx> wrote: > > On Wed Jan 24, 2024 at 6:28 PM CET, Théo Lebrun wrote: > > > On Wed Jan 24, 2024 at 4:14 PM CET, Rob Herring wrote: > > > > On Tue, Jan 23, 2024 at 07:46:49PM +0100, Théo Lebrun wrote: [...] > > > > > + }; > > > > > + > > > > > + pinctrl-b { > > > > > + compatible = "mobileye,eyeq5-b-pinctrl"; > > > > > + #pinctrl-cells = <1>; > > > > > + }; > > > > > + }; > > > > > > > > This can all be simplified to: > > > > > > > > system-controller@e00000 { > > > > compatible = "mobileye,eyeq5-olb", "syscon"; > > > > reg = <0xe00000 0x400>; > > > > #reset-cells = <2>; > > > > #clock-cells = <1>; > > > > clocks = <&xtal>; > > > > clock-names = "ref"; > > > > > > > > pins { ... }; > > > > }; > > > > > > > > There is no need for sub nodes unless you have reusable blocks or each > > > > block has its own resources in DT. > > > > > > That is right, and it does simplify the devicetree as you have shown. > > > However, the split nodes gives the following advantages: > > > > > > - Devicetree-wise, it allows for one alias per function. > > > `clocks = <&clocks EQ5C_PLL_CPU>` is surely more intuitive > > > than `clocks = <&olb EQ5C_PLL_CPU>;`. Same for reset. > > clocks: resets: pinctrl: system-controller@e00000 { > > > > > > > - It means an MFD driver must be implemented, adding between 100 to 200 > > > lines of boilerplate code to the kernel. > > From a binding perspective, not my problem... That's Linux details > defining the binding. What about u-boot, BSD, future versions of Linux > with different structure? > > I don't think an MFD is required here. A driver should be able to be > both clock and reset provider. That's pretty common. pinctrl less so. @Rob & @Krzysztof: following Krzysztof's question about the memory map and adding ressources to the system-controller, I was wondering if the following approach would be more suitable: olb: system-controller@e00000 { compatible = "mobileye,eyeq5-olb", "syscon", "simple-mfd"; reg = <0 0xe00000 0x0 0x400>; #address-cells = <1>; #size-cells = <1>; clocks: clock-controller { compatible = "mobileye,eyeq5-clk"; reg = <0x02c 0x7C>; #clock-cells = <1>; clocks = <&xtal>; clock-names = "ref"; }; reset: reset-controller { compatible = "mobileye,eyeq5-reset"; reg = <0x004 0x08>, <0x120 0x04>, <0x200 0x34>; reg-names = "d0", "d2", "d1"; #reset-cells = <2>; }; pinctrl0: pinctrl-a { compatible = "mobileye,eyeq5-a-pinctrl"; reg = <0x0B0 0x30>; }; pinctrl1: pinctrl-b { compatible = "mobileye,eyeq5-b-pinctrl"; reg = <0x0B0 0x30>; }; }; It highlights that they are in fact separate controllers and not one device. The common thing between them is that they were custom-implemented by Mobileye and therefore all registers were put in a single block. Else we'll go with the driver that implements both the clock & reset providers. It'd live in drivers/clk/ I believe, as this is where other drivers of the sort live. > > > - It means one pinctrl device for the two banks. That addresses your > > > comment on [PATCH v3 10/17]. This is often done and would be doable > > > on this platform. However it means added logic to each individual > > > function of pinctrl-eyeq5. > > If it makes things easier, 2 'pins' sub-nodes is fine. That's just > container nodes. > > > > Overall it makes for less readable code, for code that already looks > > > more complex than it really is. > > > > > > My initial non-public version of pinctrl-eyeq5 was using this method > > > (a device handling both banks) and I've leaned away from it. > > > > I had forgotten one other reason: > > > > - Reusability does count for something. Other Mobileye platforms exist, > > and the system controller stuff is more complex on those. Multiple > > different OLB blocks, etc. But my understanding is that > > per-peripheral logic is reused across versions. > > IME, this stuff never stays exactly the same from chip to chip. If it helps, I have access to the downstream vendor kernel to see how things work there. It supports the next generation of Mobileye hardware. Regards, -- Théo Lebrun, Bootlin Embedded Linux and Kernel engineering https://bootlin.com