+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 > _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot