From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jon Hunter Subject: Re: [PATCH] ARM64: tegra: Add support for Google Pixel C Date: Thu, 7 Jan 2016 16:53:24 +0000 Message-ID: <568E9804.5020503@nvidia.com> References: <1452073222-2956-1-git-send-email-jonathanh@nvidia.com> <568D0D70.4020309@nvidia.com> <568E65F0.2070201@nvidia.com> <4442990.rM1mk43t6M@wuerfel> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4442990.rM1mk43t6M@wuerfel> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Arnd Bergmann Cc: Mark Rutland , Rob Herring , Pawel Moll , Ian Campbell , Kumar Gala , Stephen Warren , Thierry Reding , Alexandre Courbot , Olof Johansson , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org On 07/01/16 14:11, Arnd Bergmann wrote: > On Thursday 07 January 2016 13:19:44 Jon Hunter wrote: >> >> Adding Arnd. >> >> Hmmm ... well apparently stdout-path does not work for tegra and in >> order to make this work I had to do the following ... >> >> >> [PATCH] serial: 8250: of: Add earlycon support for Tegra >> >> Currently, early console support only works for Tegra when the serial >> port information is passed via the earlycon boot parameter. If the >> serial port information is specified via device-tree using the >> "stdout-path" then the early console does not work because: >> >> 1. The tegra serial ports compatibility parameter does not match any >> of the supported serial drivers for early console. >> 2. The of_setup_earlycon() function assumes that serial port registers >> are byte aligned and for tegra they are 32-bit aligned. >> >> Add an early console setup function for tegra so that the early console >> can be specified via the device-tree "stdout-path" variable. >> >> Signed-off-by: Jon Hunter >> --- >> drivers/tty/serial/8250/8250_of.c | 10 ++++++++++ >> 1 file changed, 10 insertions(+) >> >> diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c >> index 33021c1f7d55..98adf83e83c2 100644 >> --- a/drivers/tty/serial/8250/8250_of.c >> +++ b/drivers/tty/serial/8250/8250_of.c >> @@ -44,6 +44,16 @@ void tegra_serial_handle_break(struct uart_port *p) >> udelay(1); >> } while (1); >> } >> + >> +int __init tegra_earlycon_setup(struct earlycon_device *device, >> + const char *options) >> +{ >> + device->port.iotype = UPIO_MEM32; >> + device->port.regshift = 2; >> + >> + return early_serial8250_setup(device, options); >> +} >> +OF_EARLYCON_DECLARE(tegra20_uart, "nvidia,tegra20-uart", tegra_earlycon_setup); >> #else >> static inline void tegra_serial_handle_break(struct uart_port *port) >> { >> >> >> Arnd, does the above look ok, or should there be a generic >> early_serial8250x32_setup() somewhere? > > I think it would be better to put it into 8250_early.c rather than > 8250_of.c, as there are already some other definitions in there, > and the #ifdef CONFIG_TEGRA in 8250_of.c is for some other workaround. Ok so something like this ... diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c index af62131af21e..4ce6e2b57534 100644 --- a/drivers/tty/serial/8250/8250_early.c +++ b/drivers/tty/serial/8250/8250_early.c @@ -141,7 +141,18 @@ int __init early_serial8250_setup(struct earlycon_device *device, device->con->write = early_serial8250_write; return 0; } + +int __init early_serial8250_mem32_setup(struct earlycon_device *device, + const char *options) +{ + device->port.iotype = UPIO_MEM32; + device->port.regshift = 2; + + return early_serial8250_setup(device, options); +} EARLYCON_DECLARE(uart8250, early_serial8250_setup); EARLYCON_DECLARE(uart, early_serial8250_setup); OF_EARLYCON_DECLARE(ns16550, "ns16550", early_serial8250_setup); OF_EARLYCON_DECLARE(ns16550a, "ns16550a", early_serial8250_setup); +OF_EARLYCON_DECLARE(tegra20_uart, "nvidia,tegra20-uart", + early_serial8250_mem32_setup); > Would it be possible to handle the "reg-io-width" parsing in > early_serial8250_setup instead of keying it off the string? Good point. I spent a bit of time looking at this, but I cannot see an easy way to do this unless we check for "reg-io-width" and "reg-shift" in early_init_dt_scan_chosen_serial() and pass to of_setup_earlycon(), however, I am guessing that this would not be ideal as this would happen for non-8250 devices. May be that would be ok, but I am not sure. Cheers Jon