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. - Mani > > "Property would be suitable if the same device, e.g. same SoC component > > with same interface towards OS, was configured differently on different > > boards." > > > > > Should we still use a different compatible? For the similar usecase, we already > > > have properties like 'qcom,controlled-remotely' to let the OS know that it > > > should not configure the hardware and just consume it. > > Yeah, also similar qcom,gsi-loader. > > > > Best regards, > > Krzysztof > > -- மணிவண்ணன் சதாசிவம்
