On Wed, Jul 13, 2016 at 12:56:51PM +0200, Andreas J. Reichel wrote:
Hardware: CM-FX6 Module from Compulab
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 common/console.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.
Although, this affects other boards as well as it touches common/console.c, the macro WATCHDOG_RESET expands to {} if watchdog support isn't configured. Hence, there's no harm caused and 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) => common/console.c: fgetc => console_tstc
common/console.c: (with CONFIG_CONSOLE_MUX is set)
- 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.
Solution: Add WATCHDOG_RESET into the loop of console_tstc.
Note: Macro expands to {} if not configured, so no #ifdef is needed.
Comment:
Signed-off-by: Christian Storm christian.storm@tngtech.com Signed-off-by: Jan Kiszka jan.kiszka@siemens.com Signed-off-by: Andreas J. Reichel Andreas.Reichel@tngtech.com Acked-by: Simon Glass sjg@chromium.org
Applied to u-boot/master, thanks!