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From: Sascha Hauer <sha@pengutronix.de>
To: Roland Hieber <rhi@pengutronix.de>
Cc: barebox@lists.infradead.org, Ahmad Fatoum <ahmad@a3f.at>,
	Andrew John <andrew@mobius-embedded-systems.co.uk>,
	Robert Carnecky <robert@neopsis.com>,
	Rouven Czerwinski <rcz@pengutronix.de>
Subject: Re: [PATCH 11/11] doc: bcm283x: document use of mini-uart on Raspberry Pi Zero W / CM3
Date: Mon, 7 Dec 2020 08:10:58 +0100	[thread overview]
Message-ID: <20201207071058.GB3977@pengutronix.de> (raw)
In-Reply-To: <20201129195042.iz25xbxifh75yryo@pengutronix.de>

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@pengutronix.de>
> > Cc: Rouven Czerwinski <rcz@pengutronix.de>
> > Cc: Robert Carnecky <robert@neopsis.com>
> > Cc: Andrew John <andrew@mobius-embedded-systems.co.uk>
> > Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
> > ---
> >  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

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  parent reply	other threads:[~2020-12-07  7:11 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-28 21:39 [PATCH 01/11] Revert "ARM: dts: bcm2835-rpi: re-enable booting from SD card" Ahmad Fatoum
2020-11-28 21:39 ` [PATCH 02/11] ARM: dts: rpi: drop unnecessary /chosen/stdout-path overrides Ahmad Fatoum
2020-11-28 21:39 ` [PATCH 03/11] ARM: rpi: make functions in rpi-common.c static Ahmad Fatoum
2020-11-28 21:39 ` [PATCH 04/11] ARM: rpi: move rpi_model_init() to postcore Ahmad Fatoum
2020-11-28 21:39 ` [PATCH 05/11] ARM: rpi: support raspberry pi 1 and zero mini-uart Ahmad Fatoum
2020-11-28 21:39 ` [PATCH 06/11] ARM: rpi: add new init function for Raspberry Pi Zero Ahmad Fatoum
2020-11-28 21:39 ` [PATCH 07/11] ARM: rpi: Add Raspberry Pi Zero W mini-uart support Ahmad Fatoum
2020-11-28 21:39 ` [PATCH 08/11] ARM: rpi: drop no longer needed environment Ahmad Fatoum
2020-11-28 21:39 ` [PATCH 09/11] ARM: rpi: fix model description string Ahmad Fatoum
2020-11-28 21:39 ` [PATCH 10/11] ARM: rpi: add new rpi boot target Ahmad Fatoum
2020-11-28 21:39 ` [PATCH 11/11] doc: bcm283x: document use of mini-uart on Raspberry Pi Zero W / CM3 Ahmad Fatoum
2020-11-29 19:50   ` Roland Hieber
2020-11-29 20:20     ` Ahmad Fatoum
2020-12-07  7:10     ` Sascha Hauer [this message]
2020-12-07 10:00       ` Ahmad Fatoum
2020-12-07 10:29         ` Sascha Hauer
2020-12-07 10:00   ` [PATCH] fixup! " Ahmad Fatoum

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