On Sun, Feb 01, 2015 at 10:45:12PM -0500, Peter Hurley wrote:
> On 02/01/2015 10:16 PM, Eddie Huang wrote:
> > Hi Peter,
> >
> > On Sun, 2015-02-01 at 13:26 -0500, Peter Hurley wrote:
> >> On 02/01/2015 11:27 AM, Peter Hurley wrote:
> >>> Hi Eddie,
> >>>
> >>> On 01/12/2015 08:08 AM, Eddie Huang wrote:
> >>>> Add earlycon support not only baudrate option, but also add noinit option.
> >>>> If use noinit option, 8250 earlycon will not init serial hardware and use
> >>>> loader setting.
> >>>
> >>> I see this went into Greg's tty-testing branch.
> >>>
> >>> The only point of this is to not program the divisor, right?
> >>>
> >>> I ask because early_serial8250_setup() could already handle this without
> >>> extra options by simply not doing divisor programming if no baud option is
> >>> present.
> >>
> >> Does the patch below work for your use-case?
> >>
> >> [ Note: the patch applies to 3.19-rcX. To test, your noinit patches need to be
> >> reverted first.
> >> ]
> >>
> >> --- >% ---
> >> From: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
> >> Subject: [PATCH] serial: 8250_early: Assume uart already initialized if no
> >> baud option
> >>
> >> The <baud><parity><bit> option string is not supplied if the earlycon
> >> is started via devicetree and OF_EARLYCON_DECLARE(). The option string
> >> is also not required if started via kernel command line parameters of
> >> the form:
> >> earlycon=uart,mmio,<addr>
> >> console=uart,mmio,<addr>
> >>
> >> If earlycon_device->baud is 0, then an option string was not supplied.
> >> In this case, assume the uart has already been initialized by the
> >> bootloader or firmware.
> >>
> >> Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
> >> ---
> >> drivers/tty/serial/8250/8250_early.c | 10 ++++++++--
> >> 1 file changed, 8 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
> >> index d7b831b..1701d00 100644
> >> --- a/drivers/tty/serial/8250/8250_early.c
> >> +++ b/drivers/tty/serial/8250/8250_early.c
> >> @@ -149,12 +149,18 @@ static int __init early_serial8250_setup(struct earlycon_device *device,
> >> return 0;
> >>
> >> if (!device->baud) {
> >> + struct uart_port *port = &device->port;
> >> + unsigned int ier;
> >> +
> >> device->baud = probe_baud(&device->port);
> >> snprintf(device->options, sizeof(device->options), "%u",
> >> device->baud);
> >> - }
> >>
> >> - init_port(device);
> >> + /* assume the device was initialized, only mask interrupts */
> >> + ier = serial8250_early_in(port, UART_IER);
> >> + serial8250_early_out(port, UART_IER, ier & UART_IER_UUE);
> >> + } else
> >> + init_port(device);
> > Should add brace in else.
>
> I don't do that unless I have to.
>
> > Where is original line here.
> > early_device = device;
>
> Whoops :)
>
> I wrote the patch from a private branch which implements extensible console
> matching (so a console can define its own match function) and a bunch of
> other console cleanup and code removal. In that series, early_device becomes
> unnecessary and is removed.
>
> I'll respin proper patches on top of Greg's tty-testing branch with reverts
> for the noinit options. I noticed that one of the noinit patches actually
> has the linkage for the mtk earlycon, so I'll be sure to preserve that.
I can just drop the patches in the tty-testing branch, that's what it is
there for :)
Just let me know the specific patches and I will do so, thanks.
greg k-h
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