On 24/01/2024 09:53, Manivannan Sadhasivam wrote: > On Wed, Jan 24, 2024 at 09:45:05AM +0100, Krzysztof Kozlowski wrote: >> 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? >> > > Sorry, I don't understand what you mean. This interface is still under > development and going to be available in future SoCs. At that time, we need > changes to the drivers to adapt to this interface. Hm, confused... The message was saying: the same hardware. Same hardware means for example Qualcomm SM8550 SoC. OK, I think we are way past possible theoretical discussions. Please send patches and we will discuss it from there. Best regards, Krzysztof
