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charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi Jonathan and Krzysztof, Thank you for the detailed guidance on the fallback compatible. On Sat, Aug 16, 2025 at 12:23=E2=80=AFPM Jonathan Cameron wrote: > > Is that second byte optional? Figure 3b seems to suggest so but I haven'= t > taken the time to read the rest of the data sheet. > If it is never written does this new device function as backwards compati= ble > with the LTC2497? > > If so a fallback compatible is appropriate. This is used when we have > new newer DT against an older driver that doesn't support new features. > > A newer kernel will match on the new ID and hence provide these extended > features you have here. > The second I2C command byte is indeed optional. If it is not sent, the LTC2495 defaults to its standard mode and functions as backwards-compatible with the LTC2497 for basic voltage readings. The new "lltc,ltc2495" compatible is therefore needed only to allow the updated driver to identify the chip and enable the temperature channel. I will rework the patch series to reflect this. > Note this discussion should have happened before you posted v2, let alone= v3 and v4! My apologies for the extra revisions and discussion on this topic. Best regards, Alper