Hi Doug
On Tue, Dec 12, 2023 at 9:54 AM Michael Nazzareno Trimarchi
<michael@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hi Doug
>
> On Mon, Dec 11, 2023 at 11:00 PM Doug Anderson <dianders@xxxxxxxxxxxx> wrote:
> >
> > Hi,
> >
> > On Mon, Dec 11, 2023 at 1:42 PM Michael Nazzareno Trimarchi
> > <michael@xxxxxxxxxxxxxxxxxxxx> wrote:
> > >
> > > > 1. init_kgdboc() runs and registers the singleton kgdb "platform driver".
> > > >
> > > > 2. The platform driver's probe function, kgdboc_probe(), runs and
> > > > checks to see if the console is ready by looking at the return value
> > > > of configure_kgdboc(). If it's ready then we're good to go. If it's
> > > > not ready then we defer.
> > > >
> > > > So I think the bug here is that somehow the console looks "ready"
> > > > (because tty_find_polling_driver() can find it) but it isn't actually
> > > > ready yet (because it crashes). That's what you need to fix.
> > > >
> > >
> > > The polling driver look for uart and uart8250_core is registered and 4 fake uart
> > > are there but there are not still replaced by platform driver that can
> > > come later.
> > > The try_polling find it but it's the isa-8250 driver. It means that
> > > add_uart 8250 is
> > > not still happen
> >
> > The 8250 driver is always a maze, so you might need to do a bunch of
> > digging. ...but it sure sounds like the console shouldn't be
> > registered until the correct ops are in place. That either means
> > getting the ops put in place earlier or deferring when the console is
> > registered...
> >
>
> Your point is pretty clear and my initial idea was to find a real fix.
> This come to avoid
> breaking existing setup but anyway I will dig in it more
>
> Michael
What about this?
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -385,6 +385,7 @@ struct tty_driver *tty_find_polling_driver(char
*name, int *line)
int tty_line = 0;
int len;
char *str, *stp;
+ int index;
for (str = name; *str; str++)
if ((*str >= '0' && *str <= '9') || *str == ',')
@@ -406,7 +407,7 @@ struct tty_driver *tty_find_polling_driver(char
*name, int *line)
if (*stp == '\0')
stp = NULL;
- if (tty_line >= 0 && tty_line < p->num && p->ops &&
+ if (tty_line >= 0 && tty_line < p->num && p->ops &&
console_device(&index) == p &&
p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
res = tty_driver_kref_get(p);
*line = tty_line;
I will send proper patch
[ 18.885348] printk: legacy console [ttyS2] disabled
[ 18.890821] 2800000.serial: ttyS2 at MMIO 0x2800000 (irq = 283,
base_baud = 3000000) is a 8250
[ 18.899727] printk: legacy console [ttyS2] enabled
[ 18.909440] printk: legacy bootconsole [ns16550a0] disabled
[ 18.923263] omap8250_probe: register uart 2800000.serial
Michael
>
> > -Doug
>
>
>
> --
> Michael Nazzareno Trimarchi
> Co-Founder & Chief Executive Officer
> M. +39 347 913 2170
> michael@xxxxxxxxxxxxxxxxxxxx
> __________________________________
>
> Amarula Solutions BV
> Joop Geesinkweg 125, 1114 AB, Amsterdam, NL
> T. +31 (0)85 111 9172
> info@xxxxxxxxxxxxxxxxxxxx
> www.amarulasolutions.com
--
Michael Nazzareno Trimarchi
Co-Founder & Chief Executive Officer
M. +39 347 913 2170
michael@xxxxxxxxxxxxxxxxxxxx
__________________________________
Amarula Solutions BV
Joop Geesinkweg 125, 1114 AB, Amsterdam, NL
T. +31 (0)85 111 9172
info@xxxxxxxxxxxxxxxxxxxx
www.amarulasolutions.com
