On 13/04/2023 00:24, Brenda Streiff wrote: > On 4/11/23 00:44, Krzysztof Kozlowski wrote: >> On 10/04/2023 23:11, Brenda Streiff wrote: >>> + >>> + interrupts: >>> + maxItems: 1 >>> + >>> + clock-frequency: true >> >> I missed it last time - why do you need this property? You do not have >> any clock input, so which clock's frequency is it? >> > > This is the clock frequency of the UART; on our x86-based platforms this > comes from the LPC clock, on Zynq-7000 it's derived from a clock in the > FPGA. This is used to set struct uart_port::uartclk in the serial core, > as it is for other UARTs. > > This clock frequency can vary based on board design (especially on the > x86 side, due to different LPC clocks) but for a given design is fixed- > frequency. So you must have clock input - clocks property. Once you add this, use assigned-clocks to get the rate you want. > > Would you prefer this be documented further? I was following 8250.yaml's > lead here with the simple `true`. I prefer to drop it. It is not correct and a legacy property. Without clock inputs how can you even configure some clock? Best regards, Krzysztof
