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.st...@tngtech.com>
> Signed-off-by: Jan Kiszka <jan.kis...@siemens.com>
> Signed-off-by: Andreas J. Reichel <andreas.reic...@tngtech.com>
> Acked-by: Simon Glass <s...@chromium.org>Applied to u-boot/master, thanks! -- Tom
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