On Sun, Nov 29, 2020 at 08:50:42PM +0100, Roland Hieber wrote: > On Sat, Nov 28, 2020 at 10:39:34PM +0100, Ahmad Fatoum wrote: > > As described in the UART configuration[1] article in the Raspberry Pi > > Foundation documentation, Raspberry Pi 3 & 4 as well as Zero W use the > > mini-uart as primary (easily user-accessible) UART. At least on the > > Raspberry Zero W and CM3, we need to pass uart_2ndstage=1, so the > > BootROM leaves the 8250 IP in a suitable state for use by barebox. > > Document this. > > > > [1]: https://www.raspberrypi.org/documentation/configuration/uart.md > > > > Cc: Roland Hieber <rhi@xxxxxxxxxxxxxx> > > Cc: Rouven Czerwinski <rcz@xxxxxxxxxxxxxx> > > Cc: Robert Carnecky <robert@xxxxxxxxxxx> > > Cc: Andrew John <andrew@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx> > > Signed-off-by: Ahmad Fatoum <ahmad@xxxxxx> > > --- > > Documentation/boards/bcm2835.rst | 7 +++++++ > > 1 file changed, 7 insertions(+) > > > > diff --git a/Documentation/boards/bcm2835.rst b/Documentation/boards/bcm2835.rst > > index c896871e0d82..dbdfc2633173 100644 > > --- a/Documentation/boards/bcm2835.rst > > +++ b/Documentation/boards/bcm2835.rst > > @@ -23,6 +23,13 @@ Raspberry Pi > > kernel=barebox.img > > enable_uart=1 > > > > + If you want to use the mini-uart instead of the PL011, you might need to additionally set:: > > + > > + uart_2ndstage=1 > > + > > + This is useful on newer boards like the Raspberry Pi Zero W and CM3, which route the > > + more easily accessible primary UART to the mini-uart. > > This seems to be non-optional on RPi Zero W, so I would word it more > strongly. > > With this series, at least barebox boots, which is better than in master > :-) However, I cannot get the stock kernel (/boot/kernel.img) to boot on > Zero W, and I cannot figure out why: Should I wait for this being fixed before I merge this series? Sascha -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox
