Re: [PATCH v2] Revert "tty: serial: meson: Add a earlycon for the T7 SoC"

[Lucas Tanure]

On 27-08-2023 10:48, Neil Armstrong wrote:
> Hi Lucas,
>
> Le 27/08/2023 à 10:29, Lucas Tanure a écrit :
> > This reverts commit 6a4197f9763325043abf7690a21124a9facbf52e.
> > New SoC will use ttyS0 instead of ttyAML, so T7 SoC doesn't need a 
> > OF_EARLYCON_DECLARE.
> >
> > Signed-off-by: Lucas Tanure <tanure@xxxxxxxxx>
> > ---
> > Since V1:
> > - add Signed-off-by:
> >
> >   drivers/tty/serial/meson_uart.c | 2 --
> >   1 file changed, 2 deletions(-)
> >
> > diff --git a/drivers/tty/serial/meson_uart.c 
> > b/drivers/tty/serial/meson_uart.c
> > index c4f61d82fb727..790d910dafa5d 100644
> > --- a/drivers/tty/serial/meson_uart.c
> > +++ b/drivers/tty/serial/meson_uart.c
> > @@ -648,8 +648,6 @@ meson_serial_early_console_setup(struct 
> > earlycon_device *device, const char *opt
> >   OF_EARLYCON_DECLARE(meson, "amlogic,meson-ao-uart",
> >               meson_serial_early_console_setup);
> > -OF_EARLYCON_DECLARE(meson, "amlogic,t7-uart",
> > -            meson_serial_early_console_setup);
> >   #define MESON_SERIAL_CONSOLE_PTR(_devname) 
> > (&meson_serial_console_##_devname)
> >   #else
>
> How do you use earlycon with this removed ?
>
> Neil
This is my kernel cmdline:
console=ttyS0,921600 no_console_suspend earlycon=ttyS0,0xfe078000

And I can see my log:
boot 64bit kernel
[    0.000000] Booting Linux on physical CPU 0x0000000000 [0x410fd092]
[    0.000000] Linux version 6.5.0-rc7-next-20230825+ (tanureal@ryzen) 
(aarch64-none-linux-gnu-gcc (GNU Toolchain for the A-profile 
Architecture 10.3-2021.07 (arm-10.29)) 10.3.1 20210621, GNU ld (GNU 
Toolchain fo3
[    0.000000] KASLR disabled due to lack of seed
[    0.000000] Machine model: Khadas vim4
[    0.000000] OF: reserved mem: 0x0000000005000000..0x00000000052fffff 
(3072 KiB) nomap non-reusable secmon@5000000
[    0.000000] OF: reserved mem: 0x0000000005300000..0x00000000072fffff 
(32768 KiB) nomap non-reusable secmon@5300000
...
[    0.079368] io scheduler mq-deadline registered
[    0.079374] io scheduler kyber registered
[    0.079549] io scheduler bfq registered
[    0.083373] fe078000.serial: ttyS0 at MMIO 0xfe078000 (irq = 14, 
base_baud = 1500000) is a meson_uart
[    0.083403] printk: console [ttyS0] enabled

As the log is OK, and T7 for now is binding against S4 code we should 
drop this patch and add a S4 one if needed.

But just having this log is not enough for testing earlycon?
I am assuming that by just having the log since 0.0000 is a good sign 
that earlycon is working.
Could you give further guidance?

Lucas Tanure