Linus Walleij wrote: > Hi Emil, > > thanks for your patch! > > On Fri, Dec 15, 2023 at 3:39 PM Emil Renner Berthing > <emil.renner.berthing@xxxxxxxxxxxxx> wrote: > > > + The TH1520 has 3 groups of pads each controlled from different memory ranges. > > + Confusingly the memory ranges are named > > + PADCTRL_AOSYS -> PAD Group 1 > > + PADCTRL1_APSYS -> PAD Group 2 > > + PADCTRL0_APSYS -> PAD Group 3 > > Really, even in the documentation? If you look at the layout on the actual > chip, does a pattern emerge? Yes, the documentation is where I got this from: https://git.beagleboard.org/beaglev-ahead/beaglev-ahead/-/blob/main/docs/TH1520%20System%20User%20Manual.pdf The pinmux chapter starting on page 31 only talks about the 3 pad groups, but if you match the base addresses, table 3-8 page 46, with the memory map, table 1-2 page 1, they same base addresses have the PADCTRL names above. > I think some use the north/south/east/west as group names with the BGA > chip facing up with the package text correctly readable then it is a bit > like a map. I don't know if or where such documentation is available. Jisheng, Guo or Drew, do you know? > > + function: > > + $ref: /schemas/types.yaml#/definitions/string > > + enum: [ "0", "1", "2", "3", "4", "5" ] > > + description: The mux function to select for the given pins. > > So why is the opaque names "0", "1" etc used, and they will be the same for > all pins I bet. Most drivers use a string identifying the actual function here. > Such as "i2c", "gpio", etc. > > Names that are just figures are *impossible* to understand without access > to a datasheet. > > The point of device trees sources are to be human readable, strings of > magic numbers are not human readable at all. > > > + bias-disable: true > > + > > + bias-pull-up: > > + type: boolean > > + > > + bias-pull-down: > > + type: boolean > > + > > + drive-strength: > > + enum: [ 1, 2, 3, 5, 7, 8, 10, 12, 13, 15, 16, 18, 20, 21, 23, 25 ] > > milliamperes? Then use drive-strength-microamp. > > If not, explain what each setting means, i.e. the number of max microamps. It *is* the number of mA. I can change it uA if that's better. > At which point using drive-strength-microamp and a translation table in the > driver may be a better idea. That's what it does, just with mA. > The only reason to use opaque numbers is if 1, 2 (etc) mean something like > "number of driver stages" with a current output that varies with technology. > > > + thead,strong-pull-up: > > + oneOf: > > + - type: boolean > > + - $ref: /schemas/types.yaml#/definitions/uint32 > > + enum: [ 0, 2100 ] > > + description: Enable or disable strong 2.1kOhm pull-up. > > Just use bias-pull-up with an argument. > > bias-pull-up = <2100000>; > > No argument would be the default setting. > > No need for custom bindings. > > > + uart0_pins: uart0-0 { > > + tx-pins { > > + pins = "UART0_TXD"; > > Pins have reasonable names, but... > > > + function = "0"; > > What about function = "uart_0" hmmm? > > Yours, > Linus Walleij > > _______________________________________________ > linux-riscv mailing list > linux-riscv@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-riscv
