On 22/11/2023 19:39, William Zhang wrote: > Hi, > > On 11/22/2023 07:52 AM, Rafał Miłecki wrote: >> On 22.11.2023 16:50, Krzysztof Kozlowski wrote: >>> On 22/11/2023 16:49, Rafał Miłecki wrote: >>>>>> For example a year ago I added binding for BCMBCA SoC timer without >>>>>> actual driver, see e112f2de151b ("dt-bindings: timer: Add Broadcom's >>>>>> BCMBCA timers"). >>>>>> >>>>>> I'm not sure if we're going to agree on this, but personally I like >>>>>> describing hardware as much as I can. So it's well documented / >>>>>> understood and people may eventually write drivers for it. Maybe it's >>>>>> partially because I come from Broadcom's world that isn't well known >>>>>> for upstream efforts in general. >>>>> >>>>> The problem is that "brcm,bcmbca-hs-uart" is not describing >>>>> hardware. It >>>>> is saying that all these devices have similar (compatible) programming >>>>> model, so the OS can use just one compatible. This goes away from pure >>>>> hardware description into interpretation. >>>>> > It is the same hardware IP block used in bcmbca SoCs. To me, it > perfectly describe the hardware IP block and it does not need fallback > because there is no fallback. We did that for SPI controller although > it has two revisions of that IP block so we have brcm,bcmbca-hsspi-v1.0 > and 1.1 > >>>>> Rob already commented on such non-SoC compatibles multiple times. I do >>>>> not see any reason here to not use specific compatible as fallback. >>>> > Sorry I missed Rob's comments. If we have any new rule or notes about > this, I would like to check it out. > >>>> Do I get it right we should rather have some base specific compatible >>>> like: "brcm,bcm63138-hs-uart" and then if anything use fallback to it >>>> like: "brcm,bcm4908-hs-uart", "brcm,bcm63138-hs-uart"; ? >>> >>> Yes, or the other way around, depends which is probably the oldest. > If we absolutely can not use bcmbca-hs-uart, I would suggest to use We can, but I am surprised that you want without any driver. What's the point of generic compatible? > bcm63xx-hs-uart to be more soc specific and in fact the oldest SoC have What is xx? Wildcard? I mean... ehhh... Best regards, Krzysztof