Re: [PATCH 7/8] serial: 8250/ingenic: Add support for the JZ4750/JZ4755 SoCs

Siarhei Volkau
2022-10-19T15:27:28Z

пн, 17 окт. 2022 г. в 12:32, Paul Cercueil <paul@crapouillou.net>:
> > I checked that approach: serial seems to be working as expected,
> > but not all the time: there's a time period when the CGU driver
> > started but serial console driver is still early one.
> > In my case UART produces garbage at that period since CGU
> > needs to enable clock divider back: ext is 24MHz but 12MHz
> > required for audio codec and USB to function properly.
>
> What I'd do, is just force-enable it to 12 MHz in ingenic_fixup_fdt(),
> since the programming manual basically says that 24 MHz does not work
> properly.
>
> Then in the earlycon setup code hardcode the /2 divider with a big fat
> comment about why it's there.

Agree, the vendor's kernel does that as well.

Also I found that:
1. Many other drivers compile the early console only when
CONFIG_SERIAL_8250_CONSOLE is set.
2. All the early ingenic_ functions can be labeled as __init.
Shall I fix that while I'm already here?