serial: 8250: Add Armada 38x earlycon support

[PATCH] serial: 8250: Add Armada 38x earlycon support

Posted by Rosen Penev 3 weeks, 2 days ago

Register the Armada 38x UART compatible with the built-in 8250
earlycon implementation so stdout-path can enable an early console
without adding a generic ns16550a compatible to the device tree.

Keeping the vendor-specific compatible avoids exposing the UART to the
generic OF 8250 runtime driver while preserving the DesignWare driver
Armada-specific runtime handling.

Assisted-by: Codex:GPT-5
Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 drivers/tty/serial/8250/8250_early.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
index 44ec209f37c4..265d49850e15 100644
--- a/drivers/tty/serial/8250/8250_early.c
+++ b/drivers/tty/serial/8250/8250_early.c
@@ -175,6 +175,7 @@ EARLYCON_DECLARE(uart8250, early_serial8250_setup);
 EARLYCON_DECLARE(uart, early_serial8250_setup);
 OF_EARLYCON_DECLARE(ns16550, "ns16550", early_serial8250_setup);
 OF_EARLYCON_DECLARE(ns16550a, "ns16550a", early_serial8250_setup);
+OF_EARLYCON_DECLARE(uart, "marvell,armada-38x-uart", early_serial8250_setup);
 OF_EARLYCON_DECLARE(uart, "nvidia,tegra20-uart", early_serial8250_setup);
 OF_EARLYCON_DECLARE(uart, "snps,dw-apb-uart", early_serial8250_setup);
 
-- 
2.55.0

Re: [PATCH] serial: 8250: Add Armada 38x earlycon support

Posted by Greg Kroah-Hartman 2 days, 20 hours ago

On Wed, Sep 02, 2026 at 03:17:09PM -0700, Rosen Penev wrote:
> Register the Armada 38x UART compatible with the built-in 8250
> earlycon implementation so stdout-path can enable an early console
> without adding a generic ns16550a compatible to the device tree.
> 
> Keeping the vendor-specific compatible avoids exposing the UART to the
> generic OF 8250 runtime driver while preserving the DesignWare driver
> Armada-specific runtime handling.
> 
> Assisted-by: Codex:GPT-5
> Signed-off-by: Rosen Penev <rosenp@gmail.com>
> ---
>  drivers/tty/serial/8250/8250_early.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
> index 44ec209f37c4..265d49850e15 100644
> --- a/drivers/tty/serial/8250/8250_early.c
> +++ b/drivers/tty/serial/8250/8250_early.c
> @@ -175,6 +175,7 @@ EARLYCON_DECLARE(uart8250, early_serial8250_setup);
>  EARLYCON_DECLARE(uart, early_serial8250_setup);
>  OF_EARLYCON_DECLARE(ns16550, "ns16550", early_serial8250_setup);
>  OF_EARLYCON_DECLARE(ns16550a, "ns16550a", early_serial8250_setup);
> +OF_EARLYCON_DECLARE(uart, "marvell,armada-38x-uart", early_serial8250_setup);
>  OF_EARLYCON_DECLARE(uart, "nvidia,tegra20-uart", early_serial8250_setup);
>  OF_EARLYCON_DECLARE(uart, "snps,dw-apb-uart", early_serial8250_setup);
>  
> -- 
> 2.55.0
> 

How was this tested?

thanks,

greg k-h

Re: [PATCH] serial: 8250: Add Armada 38x earlycon support

Posted by Rosen Penev 2 days, 14 hours ago

On Wed, Sep 23, 2026 at 5:22 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Wed, Sep 02, 2026 at 03:17:09PM -0700, Rosen Penev wrote:
> > Register the Armada 38x UART compatible with the built-in 8250
> > earlycon implementation so stdout-path can enable an early console
> > without adding a generic ns16550a compatible to the device tree.
> >
> > Keeping the vendor-specific compatible avoids exposing the UART to the
> > generic OF 8250 runtime driver while preserving the DesignWare driver
> > Armada-specific runtime handling.
> >
> > Assisted-by: Codex:GPT-5
> > Signed-off-by: Rosen Penev <rosenp@gmail.com>
> > ---
> >  drivers/tty/serial/8250/8250_early.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
> > index 44ec209f37c4..265d49850e15 100644
> > --- a/drivers/tty/serial/8250/8250_early.c
> > +++ b/drivers/tty/serial/8250/8250_early.c
> > @@ -175,6 +175,7 @@ EARLYCON_DECLARE(uart8250, early_serial8250_setup);
> >  EARLYCON_DECLARE(uart, early_serial8250_setup);
> >  OF_EARLYCON_DECLARE(ns16550, "ns16550", early_serial8250_setup);
> >  OF_EARLYCON_DECLARE(ns16550a, "ns16550a", early_serial8250_setup);
> > +OF_EARLYCON_DECLARE(uart, "marvell,armada-38x-uart", early_serial8250_setup);
> >  OF_EARLYCON_DECLARE(uart, "nvidia,tegra20-uart", early_serial8250_setup);
> >  OF_EARLYCON_DECLARE(uart, "snps,dw-apb-uart", early_serial8250_setup);
> >
> > --
> > 2.55.0
> >
>
> How was this tested?
This is actually a bugfix to avoid having to add "ns16550a" in dts,
which arose from a dt bindings commit asking why "ns16550a" is even
needed.

Anyway, the actual earlycon functionality was probably tested on a
Turris Omnia given the author of 62480772263a
>
> thanks,
>
> greg k-h