From: Lukas Wunner <lukas@wunner.de>
To: matthias.bgg@kernel.org
Cc: gregkh@linuxfoundation.org, jslaby@suse.com,
nsaenzjulienne@suse.de, linux-kernel@vger.kernel.org,
linux-serial@vger.kernel.org,
linux-rpi-kernel@lists.infradead.org,
linux-arm-kernel@lists.infradead.org,
Matthias Brugger <mbrugger@suse.com>,
Florian Fainelli <f.fainelli@gmail.com>,
Ray Jui <rjui@broadcom.com>,
Scott Branden <sbranden@broadcom.com>,
Stephen Boyd <swboyd@chromium.org>,
bcm-kernel-feedback-list@broadcom.com
Subject: Re: [PATCH] serial: 8250_early: Add earlycon for BCM2835 aux uart
Date: Sun, 26 Jan 2020 14:12:38 +0100 [thread overview]
Message-ID: <20200126131238.c65zj3wo3srafa7z@wunner.de> (raw)
In-Reply-To: <20200126123314.3558-1-matthias.bgg@kernel.org>
On Sun, Jan 26, 2020 at 01:33:14PM +0100, matthias.bgg@kernel.org wrote:
> +#ifdef CONFIG_SERIAL_8250_CONSOLE
> +
> +static int __init early_bcm2835aux_setup(struct earlycon_device *device,
> + const char *options)
> +{
> + if (!device->port.membase)
> + return -ENODEV;
> +
> + device->port.iotype = UPIO_MEM32;
> + device->port.regshift = 2;
> +
> + return early_serial8250_setup(device, NULL);
> +}
> +
> +OF_EARLYCON_DECLARE(bcm2835aux, "brcm,bcm2835-aux-uart",
> + early_bcm2835aux_setup);
> +#endif
Does this really work? I also tried to get it working recently and
the system just hung on boot. Looking at it with a JTAG debugger
showed that the bcm2835aux registers were inaccessible because
the mini UART wasn't enabled in the AUXENB register.
Maybe if you use OF_EARLYCON_DECLARE, the firmware recognizes that
serial1 is set as stdout-path and performs enablement of the mini UART?
Or are you using U-Boot which perhaps does the enablement?
I also saw in the JTAG debugger that the uartclk member contained
an incorrect value, so I'd expect that it has to be set as well in
early_bcm2835aux_setup().
I'll see to it that I give this patch a whirl when I return to the
office next week.
Thanks,
Lukas
next prev parent reply other threads:[~2020-01-26 13:12 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-26 12:33 [PATCH] serial: 8250_early: Add earlycon for BCM2835 aux uart matthias.bgg
2020-01-26 13:12 ` Lukas Wunner [this message]
2020-01-26 20:20 ` Matthias Brugger
2020-01-28 12:42 ` Nicolas Saenz Julienne
2020-01-28 14:19 ` Lukas Wunner
2020-01-30 16:11 ` Nicolas Saenz Julienne
2020-01-31 15:24 ` Lukas Wunner
2020-02-03 19:10 ` Nicolas Saenz Julienne
2020-02-12 13:28 ` Lukas Wunner
2020-02-12 15:18 ` Matthias Brugger
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