On 07/08/2022 14:11, Corey Minyard wrote: > On Sun, Aug 07, 2022 at 11:03:56AM +0300, Tomer Maimon wrote: >> Hi Corey, >> >> Thanks for your comment. >> >> On Fri, 5 Aug 2022 at 14:58, Corey Minyard <minyard@xxxxxxx> wrote: >>> >>> On Thu, Aug 04, 2022 at 09:18:00PM +0300, Tomer Maimon wrote: >>>> Add to npcm845 KCS compatible string a fallback to npcm750 KCS compatible >>>> string becuase NPCM845 and NPCM750 BMCs are using identical KCS modules. >>>> >>>> Signed-off-by: Tomer Maimon <tmaimon77@xxxxxxxxx> >>>> --- >>>> Documentation/devicetree/bindings/ipmi/npcm7xx-kcs-bmc.txt | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/Documentation/devicetree/bindings/ipmi/npcm7xx-kcs-bmc.txt b/Documentation/devicetree/bindings/ipmi/npcm7xx-kcs-bmc.txt >>>> index cbc10a68ddef..4fda76e63396 100644 >>>> --- a/Documentation/devicetree/bindings/ipmi/npcm7xx-kcs-bmc.txt >>>> +++ b/Documentation/devicetree/bindings/ipmi/npcm7xx-kcs-bmc.txt >>>> @@ -7,7 +7,7 @@ used to perform in-band IPMI communication with their host. >>>> Required properties: >>>> - compatible : should be one of >>>> "nuvoton,npcm750-kcs-bmc" >>>> - "nuvoton,npcm845-kcs-bmc" >>>> + "nuvoton,npcm845-kcs-bmc", "nuvoton,npcm750-kcs-bmc" >>> >>> This is just wrong. The compatible is supposed to identify the device, >>> not the board the device is on. I think compatible here should be >>> "npcm7xx-kcs-bmc", and just use that everywhere. It's fine if that is >>> used on a board named npcm845. >> The NPCM8XX is not a board, The Nuvoton NPCM8XX is a fourth-generation >> BMC SoC device family. > > Ok, but same principle applies. > > If the device is exactly the same, then you would only use one of the > "npcm7xx-kcs-bmc" and put that in both device trees. You can use > "nuvoton,npcm750-kcs-bmc", it's really not that important. Or even > "nuvoton,npcm-kcs-bmc" No, because it is too generic. Compatibles must be specific. > > If the device has a minor difference that can be expressed in a > parameter, then create a parameter for it. > > If the device has enough differences that a parameter or two doesn't > cover it, then you put either nuvoton,npcm750-kcs-bmc or > nuvoton,npcm750-kcs-bmc in the device tree. Not both. Then you need > two entries in the of_device_id array and you use the data field or > something to express the difference. It's quite common to have generic and specific compatibles for compatible devices and a driver which can match to both of them. I don't understand where is exactly the problem here? > > Since there appears to be no difference, just put > "nuvoton,npcm750-kcs-bmc" in the npcm845 and I will drop the patch > adding all this. T Again no, because recommended (also writing bindings document) is always to have a specific compatible. > hen a patch can be added saying it applies to both > the 7xx and 8xx series of BMC SOCs. If you want to change the name, > then a patch will be needed for that, but then you will need multiple > entries in your device tree, but you would not document it as such, as > there would only be one that applies for this kernel. > > I'm pretty sure the only reason to have muliple compatible entries in a > device tree is to cover multiple kernels where the name changed. Best regards, Krzysztof
