On Wed, Feb 22, 2023 at 07:46:25PM +0100, Krzysztof Kozlowski wrote: > On 22/02/2023 18:20, Andy Shevchenko wrote: > >> > >>> Which effectively breaks i.e. user-space instantiation for other display > >>> types which now do work due to i2c_of_match_device(). > >>> (so my suggestion above is not sufficient). > >>> > >>> Are you proposing extending and searching the I2C ID table to work around > >>> that? > >> > >> See (1) above. This is the downside I have noticed after sending this series. > >> So, the I²C ID table match has to be restored, but the above mentioned issues > >> with existing table are not gone, hence they need to be addressed in the next > >> version. > > > > I see now what you mean. So, we have even more issues in this driver: > > - I²C table is not in sync with all devices supported > > Does anything actually rely on i2c_device_id table? ACPI would match > either via ACPI or OF tables. All modern ARM systems (e.g. imx6) are > DT-based. Maybe just drop the I2C ID table? For I²C it's still possible to enumerate the device via sysfs, which is ABI. > > - the OF ID table seems has something really badly formed for adafruit > > (just a number after a comma) > > Maybe it is a model number? It was documented: > Documentation/devicetree/bindings/auxdisplay/holtek,ht16k33.yaml Yes, it's not a problem for ACPI/DT platforms, the problem is for the above way of enumeration, so if we have more than 1 manufacturer that uses plain numbers for the model, I²C framework may not distinguish which driver to use. I.o.w. the part after comma in the compatible strings of the I²C devices must be unique globally to make that enumeration disambiguous. > > The latter shows how broken it is. The I²C ID table mechanism is used as > > a backward compatibility to the OF. Unfortunately, user space may not provide > > the data except in form of DT overlays, so for the legacy enumeration we > > have only device name, which is a set of 4 digits for adafruit case. > > > > Now imagine if by some reason we will get adafruit2 (you name it) with > > the same schema. How I²C framework can understand that you meant adafruit > > and not adafruit2? Or did I miss something? -- With Best Regards, Andy Shevchenko
