Re: [PATCH v3 1/2] serial: earlycon: add uart_clk_freq parameter

Markus Probst <[email protected]> Sun, 12 Jul 2026 16:36:17 +0000

Newsgroups	org.kernel.vger.linux-serial,org.kernel.vger.linux-acpi,org.kernel.vger.linux-kernel
Message-ID	<[email protected]>

On Fri, 2026-07-10 at 14:36 +0200, Greg Kroah-Hartman wrote:
> On Mon, Jun 15, 2026 at 12:40:21AM +0000, Markus Probst wrote:
> > Add function `setup_earlycon_with_uartclk`. This allows the
> > options string to be reused with `add_preferred_console`, while still
> > allowing to set the uart clock frequency. This will be used in the
> > following commit ("ACPI: SPCR: Support UART clock frequency field").
> > 
> > No logical change intended.
> > 
> > Signed-off-by: Markus Probst <[email protected]>
> > ---
> >  drivers/tty/serial/earlycon.c | 17 ++++++++++++-----
> >  include/linux/serial_core.h   | 11 +++++++++--
> >  2 files changed, 21 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
> > index ab9af37f6cda..5a20fe9e3fb6 100644
> > --- a/drivers/tty/serial/earlycon.c
> > +++ b/drivers/tty/serial/earlycon.c
> > @@ -135,11 +135,14 @@ static int __init parse_options(struct earlycon_device *device, char *options)
> >  	return 0;
> >  }
> >  
> > -static int __init register_earlycon(char *buf, const struct earlycon_id *match)
> > +static int __init register_earlycon(char *buf, unsigned int uart_clk_freq,
> > +				    const struct earlycon_id *match)
> >  {
> >  	int err;
> >  	struct uart_port *port = &early_console_dev.port;
> >  
> > +	port->uartclk = uart_clk_freq;
> 
> This looks like a logical change, the code today does not do that
> anywhere, right?

`register_earlycon` only gets executed once.
Thus early_console_dev.port->uartclk is always 0.
Since all current callers in this patch series use `setup_earlycon`,
the uart_clk_freq parameter is also always 0.

So in case of behaviour/logic, this line does nothing without the 2.
patch.

Thanks
- Markus Probst

> 
> thanks,
> 
> greg k-h

signature.asc (application/pgp-signature, 870 B)