Re: [PATCH 1/2] dt-bindings: reset: Updated binding for Versal-NET reset driver

[Michal Simek]

On 7/18/23 16:04, Krzysztof Kozlowski wrote:
> On 18/07/2023 16:01, Michal Simek wrote:
> > On 7/18/23 15:20, Krzysztof Kozlowski wrote:
> > > On 18/07/2023 15:11, Michal Simek wrote:
> > > > > > That numbers in DT are virtual no matter if you use ID from 0 to max or random
> > > > > > values it is up to code to handle them. Checking nr_pins against ID is done in
> > > > > > core but it is up to drivers.
> > > > >
> > > > > No, you confuse "virtual" and "ID". IDs are not virtual. IDs are real
> > > > > and have representation in Linux driver. You do not need to define
> > > > > anything virtual in the bindings.
> > > >
> > > > Not sure how you define ID itself. But HW doesn't know ID. HW knows only
> > > > register which you can use to perform the reset. It is not really 128bit
> > > > register where every bit targets to different IP.
> > > >
> > > > And this is SW-firmware interface like SCMI reset driver.
> > > >
> > > > Firmware is saying that ID 0 is QSPI, ID 1 is MMC.
> > > > Their Linux driver is asking for nr_reset via firmware call which can be
> > > > different for different SOC and that's fine and I have no problem with it.
> > > > But only SCMI server is dictating that ID 0 is QSPI and ID 1 is MMC. Different
> > > > SCMI server implementation can map it differently.
> > >
> > > Sure, and all this points to: no need for bindings.
> > >
> > > > > > In our case that IDs are coming from firmware and driver itself is just matching
> > > > > > them.
> > > > >
> > > > > So they are the same as if coming from hardware - no need for IDs.
> > > >
> > > > It is hard to say what hardware here exactly is. From my perspective and I am
> > > > not advocating not using IDs from 0 to max, it is just a number.
> > > >
> > > > If my firmware knows that QSPI reset is 0xc10402dU then I will just pass it to
> > > > reach my goal which is reset QSPI IP.
> > > >
> > > > If you think that we should use IDs from 0 to max NR I am happy to pass this
> > > > message to PM team and we should extend any SW to do translation between.
> > >
> > > When we talk about IDs and bindings, we mean IDs meaningful to Linux.
> > > Whatever is ignored by Linux and passed to anyone else - hardware or
> > > firmware - is not a ID anymore from bindings point of view. It's just
> > > some value.
> >
> > Please correct me if I am wrong. Description about ID should be removed from
> > commit message because it is not necessary. And
> > include/dt-bindings/reset/xlnx-versal-net-resets.h
> > should be added when we merge also DT for versal-net SOC.
>
> No, the binding header is needed only if driver is using it. Adding DTS
> will not change that - still no kernel driver users. No benefits of such
> binding. If there are no users and no benefits - don't make it a binding.

But header in board folder should be fine like these.
arch/arm64/boot/dts/mediatek/mt2712-pinfunc.h
arch/arm64/boot/dts/mediatek/mt8516-pinfunc.h
arch/arm64/boot/dts/mediatek/mt8167-pinfunc.h
arch/arm64/boot/dts/mediatek/mt8173-pinfunc.h
arch/arm64/boot/dts/exynos/exynos-pinctrl.h
arch/arm64/boot/dts/freescale/imx8mq-pinfunc.h
arch/arm64/boot/dts/freescale/imx8mp-pinfunc.h
arch/arm64/boot/dts/freescale/imx8mn-pinfunc.h
arch/arm64/boot/dts/freescale/imx93-pinfunc.h
arch/arm64/boot/dts/freescale/imx8ulp-pinfunc.h
arch/arm64/boot/dts/freescale/imx8mm-pinfunc.h
arch/arm64/boot/dts/tesla/fsd-pinctrl.h

Thanks,
Michal