On 01/06/2021 08:07, Chen-Yu Tsai wrote: > Hi, > > On Tue, Jun 1, 2021 at 1:50 PM Jianjun Wang <jianjun.wang@xxxxxxxxxxxx> wrote: >> >> On Tue, 2021-06-01 at 11:53 +0800, Chen-Yu Tsai wrote: >>> Hi, >>> >>> On Tue, Jun 1, 2021 at 10:50 AM Jianjun Wang <jianjun.wang@xxxxxxxxxxxx> wrote: >>>> >>>> MT8195 is an ARM platform SoC which has the same PCIe IP with MT8192. >>> >>> Based on what I'm seeing internally, there seems to be some inconsistency >>> across the MediaTek platform on whether new compatible strings should be >>> introduced for "fully compatible" IP blocks. >>> >>> If this hardware block in MT8195 is "the same" as the one in MT8192, do we >>> really need the new compatible string? Are there any concerns? >> >> Hi Chen-Yu, >> >> It's ok to reuse the compatible string with MT8192, but I think this >> will be easier to find which platforms this driver is compatible with, >> especially when we have more and more platforms in the future. > > If it's just for informational purposes, then having the MT8192 compatible > as a fallback would work, and we wouldn't need to make changes to the driver. > This works better especially if we have to support multiple operating systems > that use device tree. > > So we would want > > "mediatek,mt8195-pcie", "mediatek,mt8192-pcie" > > and > > "mediatek,mt8192-pcie" > > be the valid options. > > Personally I'm not seeing enough value to justify adding the compatible string > just for informational purposes though. One could easily discern which hardware > is used by looking at the device tree. > I agree, if no differences between the two chips are known, adding a binding withe new compatible and a fallback is a good thing. If we later on realize that mt8195 PCI block has differences, we can add the matching to the driver. Regards, Matthias > > Regards > ChenYu > > >> Thanks. >>> >>> >>> Thanks >>> ChenYu >>> >>> >>>> Signed-off-by: Jianjun Wang <jianjun.wang@xxxxxxxxxxxx> >>>> --- >>>> Documentation/devicetree/bindings/pci/mediatek-pcie-gen3.yaml | 4 +++- >>>> 1 file changed, 3 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/Documentation/devicetree/bindings/pci/mediatek-pcie-gen3.yaml b/Documentation/devicetree/bindings/pci/mediatek-pcie-gen3.yaml >>>> index e7b1f9892da4..d5e4a3e63d97 100644 >>>> --- a/Documentation/devicetree/bindings/pci/mediatek-pcie-gen3.yaml >>>> +++ b/Documentation/devicetree/bindings/pci/mediatek-pcie-gen3.yaml >>>> @@ -48,7 +48,9 @@ allOf: >>>> >>>> properties: >>>> compatible: >>>> - const: mediatek,mt8192-pcie >>>> + oneOf: >>>> + - const: mediatek,mt8192-pcie >>>> + - const: mediatek,mt8195-pcie >>>> >>>> reg: >>>> maxItems: 1 >>>> -- >>>> 2.18.0 >>>> _______________________________________________ >>>> Linux-mediatek mailing list >>>> Linux-mediatek@xxxxxxxxxxxxxxxxxxx >>>> http://lists.infradead.org/mailman/listinfo/linux-mediatek >>
