On Mon, 5 Jun 2023, Uwe Kleine-König wrote:
> Hello Ilpo,
>
> On Mon, Jun 05, 2023 at 04:44:08PM +0300, Ilpo Järvinen wrote:
> > On Mon, 5 Jun 2023, Uwe Kleine-König wrote:
> > > On Mon, Jun 05, 2023 at 04:22:55PM +0300, Ilpo Järvinen wrote:
> > > > On Mon, 5 Jun 2023, Uwe Kleine-König wrote:
> > > >
> > > > > The need to handle the FSL variant of 8250 in a special way is also
> > > > > present without console support. So soften the dependency for
> > > > > SERIAL_8250_FSL accordingly. Note that with the 8250 driver compiled
> > > > > as
> > > > > a module, some devices still might not make use of the needed
> > > > > workarounds. That affects the ports instantiated in
> > > > > arch/powerpc/kernel/legacy_serial.c.
> > > > >
> > > > > This issue was identified by Dominik Andreas Schorpp.
> > > > >
> > > > > To cope for CONFIG_SERIAL_8250=m + CONFIG_SERIAL_8250_FSL=y,
> > > > > 8250_fsl.o
> > > > > must be put in the same compilation unit as 8250_port.o because the
> > > > > latter defines some functions needed in the former and so 8250_fsl.o
> > > > > must not be built-in if 8250_port.o is available in a module.
> > > > >
> > > > > Acked-by: Ilpo Järvinen <ilpo.jarvi...@linux.intel.com>
> > > > > Link:
> > > > > https://lore.kernel.org/r/20230531083230.2702181-1-u.kleine-koe...@pengutronix.de
> > > > > Signed-off-by: Uwe Kleine-König <u.kleine-koe...@pengutronix.de>
> > > > > ---
> > > > > drivers/tty/serial/8250/Kconfig | 2 +-
> > > > > drivers/tty/serial/8250/Makefile | 2 +-
> > > > > 2 files changed, 2 insertions(+), 2 deletions(-)
> > > > >
> > > > > diff --git a/drivers/tty/serial/8250/Kconfig
> > > > > b/drivers/tty/serial/8250/Kconfig
> > > > > index 5313aa31930f..10c09b19c871 100644
> > > > > --- a/drivers/tty/serial/8250/Kconfig
> > > > > +++ b/drivers/tty/serial/8250/Kconfig
> > > > > @@ -378,7 +378,7 @@ config SERIAL_8250_BCM2835AUX
> > > > >
> > > > > config SERIAL_8250_FSL
> > > > > bool "Freescale 16550 UART support" if COMPILE_TEST && !(PPC ||
> > > > > ARM || ARM64)
> > > > > - depends on SERIAL_8250_CONSOLE
> > > > > + depends on SERIAL_8250
> > > >
> > > > Just one additional thought: After the adding the arch side
> > > > workaround/hack, SERIAL_8250_FSL could become a tristate?
> > >
> > > I see no benefit for a module separate from 8250_base.ko. There are
> > > dependencies in both directions between 8250_port.o and 8250_fsl.o[1].
> > > So in my book a bool SERIAL_8250_FSL that modifies 8250_base.ko (with
> > > SERIAL_8250=m) is fine.
> > >
> > > Best regards
> > > Uwe
> > >
> > > [1] 8250_port.o uses fsl8250_handle_irq() from 8250_fsl.o
> >
> > Is that after some fix which isn't in tty-next? I see only these:
> >
> > $ git grep -l fsl8250_handle_irq
> > arch/powerpc/kernel/legacy_serial.c
> > drivers/tty/serial/8250/8250_fsl.c
> > drivers/tty/serial/8250/8250_of.c
> > include/linux/serial_8250.h
> >
> > No users of fsl8250_handle_irq in 8250_port.c.
>
> Ah right, I was too quick:
>
> 8250_of.o uses fsl8250_handle_irq() from 8250_fsl.o
> 8250_fsl.o uses serial8250_modem_status() from 8250_port.o (which is in
> 8250_base.o)
>
>
> However linking 8250_fsl.o in 8250_of.o isn't a good solution either as
> 8250_fsl.o should also be available with CONFIG_SERIAL_OF_PLATFORM
> disabled to provide the ACPI driver. And as 8250_of.o already depends on
> 8250_port.o (e.g. via serial8250_em485_config()) adding 8250_fsl.o
> together with 8250_port.o into 8250_base.ko is fine and doesn't add new
> dependencies.
So we have dependencies one-way only:
8250_port
/\ |\
\
8250_fsl \
/
/\ /
8250_of
There's no loop here, both they be indepedent modules and configured
independently (with a correct IS_*() in 8250_of.c).
--
i.
