Hi Tom,
is my patch going to be applied or is the problem resolved
otherwhise?
Kind regards
Andreas
On Mo, Sep 05, 2016 at 07:04:53 -0600, Simon Glass wrote:
> +Tom, in case this should go into the release.
>
> On 1 August 2016 at 05:49, Andreas J. Reichel
> <andreas.reic...@tngtech.com> wrote:
> > This patch fixes unwanted watchdog resets while the user enters
> > a command at the U-Boot prompt.
> >
> > As found on the CM-FX6 board from Compulab, when having enabled the
> > watchdog, a missing WATCHDOG_RESET call in _serial_tstc() in
> > (/drivers/serial/serial-uclass.c) causes this and alike boards to
> > reset when the watchdog's timeout has elapsed while waiting at the
> > U-Boot prompt.
> >
> > Despite the user could press several keys within the watchdog
> > timeout limit, the while loop in cli_readline.c, line 261, does only
> > call WATCHDOG_RESET if first == 1, which gets set to 0 in the 1st
> > loop iteration. This leads to a watchdog timeout no matter if the
> > user presses keys or not.
> >
> > The problem is solved with a call to WATCHDOG_RESET in _serial_tstc,
> > defined in drivers/serial/serial-uclass.c.
> >
> > Since the macro WATCHDOG_RESET expands to {} if watchdog support
> > isn't configured, there's no need to surround it by #ifdef in this
> > case.
> >
> > * Symptom:
> > U-Boot resets after watchdog times out when in commandline prompt
> > and watchdog is enabled.
> >
> > * Reasoning:
> > When U-Boot shows the commandline prompt, the following function
> > call stack is executed while waiting for a keypress:
> >
> > common/main.c:
> > main_loop => common/cli.c: cli_loop() =>
> > common/cli_hush.c:
> > parse_file_outer => parse_stream_outer =>
> > parse_stream => b_getch(i) =>
> > i->get(i) => file_get =>
> > get_user_input => cmdedit_read_input =>
> > uboot_cli_readline =>
> > common/cli_readline.c:
> > cli_readline => cli_readline_into_buffer =>
> > cread_line => getcmd_getch (== getc) =>
> > commonn/console.c:
> > fgetc => console_tstc
> >
> > - in console_tstc line 181:
> > If dev->tstc(dev) returns 0, the global tstcdev variable doesn't
> > get set. This is the case if no character is in the serial buffer.
> >
> > - in fgetc(int file), line 297:
> > Program flow keeps looping because tstcdev does not get set.
> > Therefore WATCHDOG_RESET is not called, as mx_serial_tstc from
> > drivers/serial/serial_mxc.c does not call it.
> >
> > - Initialization calls drv_system_init in stdio.c, which sets
> > dev.tstc = stdio_serial_tstc. Thus, dev->tstc(dev) calls serial_tstc()
> > which in turn calls _serial_tstc().
> >
> > Hence, _serial_tstc() needs to call WATCHDOG_RESET() to periodically
> > reset the watchdog while cli_readline waits for user input.
> >
> > Signed-off-by: Christian Storm <christian.st...@tngtech.com>
> > Signed-off-by: Jan Kiszka <jan.kis...@siemens.com>
> > Signed-off-by: Andreas J. Reichel <andreas.reic...@tngtech.com>
> > ---
> >
> > Changes in v2:
> > - Move WATCHDOG_RESET() call from common/console.c to
> > drivers/serial/serial-uclass.c.
> >
> > drivers/serial/serial-uclass.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/serial/serial-uclass.c b/drivers/serial/serial-uclass.c
> > index 0ce5c44..72cf808 100644
> > --- a/drivers/serial/serial-uclass.c
> > +++ b/drivers/serial/serial-uclass.c
> > @@ -155,6 +155,7 @@ static int _serial_tstc(struct udevice *dev)
> > {
> > struct dm_serial_ops *ops = serial_get_ops(dev);
> >
> > + WATCHDOG_RESET();
> > if (ops->pending)
> > return ops->pending(dev, true);
>
> Great explanation, thank you.
>
> Acked-by: Simon Glass <s...@chromium.org>
>
> >
> > --
> > 2.8.2
> >
--
Andreas Reichel
Dipl.-Phys. (Univ.)
Software Consultant
andreas.reic...@tngtech.com
+49-174-3180074
TNG Technology Consulting GmbH, Betastr. 13a, 85774 Unterföhring
Geschäftsführer: Henrik Klagges, Christoph Stock, Dr. Robert Dahlke
Sitz: Unterföhring * Amtsgericht München * HRB 135082
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