Messages in this thread | | | Subject | Re: [PATCH] tty: serial: meson: Implement earlycon support | From | Andreas Färber <> | Date | Mon, 8 Feb 2016 12:50:43 +0100 |
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Hi Peter,
Am 08.02.2016 um 05:22 schrieb Peter Hurley: > On 02/07/2016 12:57 PM, Andreas Färber wrote: >> Reuse the existing console write implementation for implementing >> DT-based and command-line-based earlycon support. >> >> Signed-off-by: Andreas Färber <afaerber@suse.de> >> --- >> Documentation/kernel-parameters.txt | 6 ++++++ >> drivers/tty/serial/meson_uart.c | 13 +++++++++++++ >> 2 files changed, 19 insertions(+) >> >> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt >> index 602065c..90801ac 100644 >> --- a/Documentation/kernel-parameters.txt >> +++ b/Documentation/kernel-parameters.txt >> @@ -1030,6 +1030,12 @@ Such letter suffixes can also be entirely omitted. >> the driver will use only 32-bit accessors to read/write >> the device registers. >> >> + meson_serial,<addr> >> + Start an early, polled-mode console on a meson serial >> + port at the specified address. The serial port must >> + already be setup and configured. Options are not yet >> + supported. >> + >> msm_serial,<addr> >> Start an early, polled-mode console on an msm serial >> port at the specified address. The serial port >> diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c >> index b12a37b..6f89567 100644 >> --- a/drivers/tty/serial/meson_uart.c >> +++ b/drivers/tty/serial/meson_uart.c >> @@ -548,6 +548,19 @@ static int __init meson_serial_console_init(void) >> } >> console_initcall(meson_serial_console_init); >> >> +static int __init >> +meson_serial_early_console_setup(struct earlycon_device *device, const char *opt) >> +{ >> + if (!device->port.membase) >> + return -ENODEV; >> + >> + device->con->write = meson_serial_console_write; > > meson_serial_console_write() is not appropriate for earlycon; it assumes the > earlycon port is the same as the driver port (it isn't).
Thanks for spotting that.
I forgot to mention that I tested this on arm64, where there is no earlyprintk any more, seemingly successfully getting a bootconsole uart0. Using co->data instead of co->index I now get meson_serial0 instead, doh.
This probably slipped though because another patch is necessary for fixing the baudrate calculation on my device.
>> + return 0; >> +} >> +EARLYCON_DECLARE(meson_serial, meson_serial_early_console_setup); >> +OF_EARLYCON_DECLARE(meson_serial, "amlogic,meson-uart", >> + meson_serial_early_console_setup); > > With today's linux-next (or Greg's tty-next tree), it is no longer necessary to > declare separate earlycon's when you want both; OF_EARLYCON_DECLARE() declares > both a devicetree-enabled earlycon and automatically provides for a command line > earlycon of the same name.
Thanks for the hint, it was based on linux-next from a couple days ago.
Is there any guidance wrt naming? I noticed that msm uses -uart in the compatible string and _serial for earlycon, so I copied that; should it rather be meson_uart or just meson?
Regards, Andreas
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