On 24/01/2024 09:39, Manivannan Sadhasivam wrote: > On Wed, Jan 24, 2024 at 09:02:16AM +0100, Krzysztof Kozlowski wrote: >> On 23/01/2024 17:12, Manivannan Sadhasivam wrote: >>> On Thu, Dec 14, 2023 at 07:18:25AM -0800, Nikunj Kela wrote: >>>> >>>> On 12/13/2023 11:49 PM, Krzysztof Kozlowski wrote: >>>>> On 14/12/2023 07:17, Manivannan Sadhasivam wrote: >>>>>> On Tue, Dec 12, 2023 at 11:06:42AM -0800, Nikunj Kela wrote: >>>>>>> + Linaro team >>>>>>> >>>>>>> On 12/12/2023 11:01 AM, Krzysztof Kozlowski wrote: >>>>>>>> On 12/12/2023 18:45, Nikunj Kela wrote: >>>>>>>>> We are abstracting some resources(ex. clocks) under new firmware on an >>>>>>>>> existing platform therefore need to make changes in certain drivers to >>>>>>>>> work with that firmware. We need to make a distinction between two >>>>>>>>> different variants of the FW. In one case, some resources will be >>>>>>>>> abstracted while in other case, they won't be abstracted. My query is - >>>>>>>>> "should we define a new compatible string for the variant with >>>>>>>>> abstracted resources(in FW) or we should add a new DT property keeping >>>>>>>>> the compatible same?" >>>>>>>> Hi, >>>>>>>> >>>>>>>> Usually change in the interface or behavior warrants new compatible. >>>>>>>> Property would be suitable if the same device, e.g. same SoC component >>>>>>>> with same FW, was configured differently on different boards. >>>>>>>> >>>>>> Here, the hardware is going to be the same, but the resources (clocks, >>>>>> regulators, etc...) will be controlled by the firmware instead of OS. >>>>> Yeah, that's the problem with generic questions, instead of specific... >>>>> "Talk is cheap." >>>>> >>>>> OK, so the hardware is exactly the same? Does FW bring any >>>>> incompatibilities in the interface or is it just about the clocks? I >>>>> guess I should not have included "with same FW" in my last statement. >>>>> It's true, but way too narrow. Therefore let me rephrase it: >>>> >>>> HW is exactly the same. Let me give more insight on the setup. We have been >>>> using the HW in virtual environment but now the ownership of certain >>>> resources (e.g. clock controller etc.) is handed over to a different VM(non >>>> Linux VM). Earlier the ownership of the resources was local to the same >>>> VM(Linux VM) via passthrough mode so it could directly access them however >>>> now Linux VM talks to non-Linux VM for its operations for resources that it >>>> doesn't own anymore via some interface(shared memory/doorbell). So shall we >>>> use property like 'qcom, controlled-remotely' or do we need a new compatible >>>> for such setup? >>>> >>> >>> Krzysztof, just a ping on this thread. >>> >>> To summarise, the hardware is exactly same. We can consider the case of UFS. The >>> UFS controller is exactly same in this proposed setup but the resources of the >>> UFS controller are taken care by the VM. So instead of enabling the resources >>> one by one, Linux kernel will just ask the VM to do so using an SCMI command. >>> >>> Due to this difference, we need to make the changes in the UFS controller >>> driver. So we want to know if we can use a different compatible for the UFS >>> controller altogether in DT (this will allow Linux kernel to have a separate >>> driver and will simplify things) or just use a property like >>> "remotely-controlled" to let the driver detect this setup and take action >>> accordingly. >> >> What devices do we talk about? Are they released? For which other >> devices you want to use it? > > If you are referring to "peripherals" as "devices", then this new interface is > going to be applicable to most of the peripherals in the SoC like PCIe, UFS, USB > etc... > And what about SoCs and final products? Best regards, Krzysztof
