On Thu, Jul 14, 2022 at 8:05 PM Peter Delevoryas <peter@xxxxxxx> wrote:
> On Thu, Jul 07, 2022 at 03:33:48PM +0200, Arnd Bergmann wrote:
> > > + model = "Facebook fby35";
> > > + compatible = "facebook,fby35", "aspeed,ast2600";
> > > +
> > > + aliases {
> > > + serial4 = &uart5;
> > > + };
> >
> > Why not start at serial0 here?
>
> Hey, Facebook person jumping in here (using a personal email):
>
> I think you're right, it should be like this:
>
> aliases {
> serial0 = &uart5;
> serial1 = &uart1;
> serial2 = &uart2;
> serial3 = &uart3;
> serial4 = &uart4;
> };
Are you actually using all five uarts though?
> > > + chosen {
> > > + stdout-path = &uart5;
> > > + bootargs = "console=ttyS4,57600n8 root=/dev/ram rw vmalloc=384M";
> > > + };
>
> Also: if we do serial0 = &uart5, it should be console=ttyS0, not ttyS4.
>
> >
> > The bootargs should really come from the boot loader.
>
> What if we want to boot the kernel by itself with QEMU? It's kinda annoying to
> have to specify '-append "console=ttyS0,57600n8...' everytime, or to have to use
> a wrapper script. But, it's also a source of bugs: I realized yesterday the
> dts we were using here:
>
> https://github.com/facebook/openbmc-linux/blob/e26c76992e0761d9e440ff514538009384c094b4/arch/arm/boot/dts/aspeed-bmc-facebook-fby35.dts
>
> Has the wrong console setting.
You can encode the uart settings like
stdout-path = "serial0:115200n8"
the rest really should be passed on the command line, not in
the DT shipped with the kernel.
Arnd
