On 22/05/2023 21:15, Kevin Hilman wrote: > Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx> writes: > >> On 16/05/2023 23:31, Kevin Hilman wrote: >> >>>> Third is to use versioned IP blocks. >>>> >>>> The second case also would work, if it is applicable to you (you really >>>> have fallback matching all devices). Third solution depends on your >>>> versioning and Rob expressed dislike about it many times. >>>> >>>> We had many discussions on mailing lists, thus simplifying the review - >>>> I recommend the first choice. For a better recommendation you should say >>>> a bit more about the block in different SoCs. >>> >>> I'll try to say a bit more about the PHY block, but in fact, it's not >>> just about differences between SoCs. On the same SoC, 2 different PHYs >>> may have different features/capabilities. >>> >>> For example, on MT8365, There are 2 PHYs: CSI0 and CSI1. CSI0 can >>> function as a C-PHY or a D-PHY, but CSI1 can only function as D-PHY >>> (used as the example in the binding patch[1].) On another related SoC, >>> there are 3 PHYs, where CSI0 is C-D but CSI1 & CSI2 are only D. >>> >>> So that's why it seems (at least to me) that while we need SoC >>> compatible, it's not enough. We also need properties to describe >>> PHY-specific features (e.g. C-D PHY) >> >> I recall the same or very similar case... It bugs me now, but >> unfortunately I cannot find it. >> >>> >>> Of course, we could rely only on SoC-specific compatibles describe this. >>> But then driver will need an SoC-specific table with the number of PHYs >>> and per-PHY features for each SoC encoded in the driver. Since the >>> driver otherwise doesn't (and shouldn't, IMHO) need to know how many >>> PHYs are on each SoC, I suggested to Julien that perhaps the additional >>> propery was the better solution. >> >> Phys were modeled as separate device instances, so you would need >> difference in compatible to figure out which phy is it. >> >> Other way could be to create device for all phys and use phy-cells=1. >> Whether it makes sense, depends on the actual datasheet - maybe the >> split phy per device is artificial? There is one PHY block with two >> address ranges for each PHY - CSI0 and CSI1 - but it is actually one >> block? You should carefully check this because once design is chosen, >> you won't be able to go back to other and it might be a problem (e.g. >> there is some top-level block for powering on all CSI instances). > > We're pretty sure these are multiple instances of the IP block as they > can operate completely independently. > >>> >>> To me it seems redundant to have the driver encode PHYs-per-SoC info, >>> when the per-SoC DT is going to have the same info, so my suggestion was >>> to simplify the driver and have this kind of hardware description in the >>> DT, and keep the driver simple, but we are definitely open to learning >>> the "right way" of doing this. >> >> The property then is reasonable. It should not be bool, though, because >> it does not scale. There can be next block which supports only D-PHY on >> CSI0 and C-PHY on CSI1? Maybe some enum or list, depending on possible >> configurations. > > OK, looks like include/dt-bindings/phy/phy.y already has > > #define PHY_TYPE_DPHY 10 > #define PHY_TYPE_CPHY 11 > > we'll add a PHY_TYPE_CDPHY and use that. Sound reasonable? Yes. Currently it is usually used as phy-cells argument (after the phy number/lane/ID), but cdns,phy-type and intel,phy-mode use it directly as property in provider. In both cases they have a bit different meaning than yours. You want to list all supported modes or narrow/restrict them. Maybe hisilicon,fixed-mode fits your purpose? Best regards, Krzysztof
