Messages in this thread | | | Date | Sun, 27 Aug 2023 11:31:35 +0100 | Subject | Re: [PATCH v2] Revert "tty: serial: meson: Add a earlycon for the T7 SoC" | From | Lucas Tanure <> |
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On 27-08-2023 11:23, Neil Armstrong wrote: > Hi Lucas, > > Le 27/08/2023 à 12:04, Lucas Tanure a écrit : >> 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@linux.com> >>>> --- >>>> 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? > > First the kernel argument is simply "earlycon" with no other options, > the earlycon code will fetch the first uart using the DT > /chosen/stdout-path property. > > Then you should see something like right after "Machine model": > [ 0.000000] earlycon: meson0 at MMIO 0x00000000ff803000 (options > '115200n8') > > The boot log you share doesn't use earlycon, it waits until all > depedency of the UART > has been probed before probing the UART driver and prints the whole boot > log. > > Earlycon is a mechanism to use the UART HW as configured by the > bootloader in > a minimal way very early in the boot in order to detect very early lockups. > > Keeping OF_EARLYCON_DECLARE for t7 would enable this. > > Neil > >> >> Lucas Tanure >> > But then we would need to add Earlycon for S4 too. How can we add one Earlycon for all future SoCs, like S4 and T7?
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