[PATCH v2 1/3] menu: fix the logic checking whether ESC key is pressed

[Daniel Golle]

On Tue, Oct 29, 2024 at 05:47:10PM +0800, Weijie Gao wrote:
> It's observed that the bootmenu on a serial console sometimes
> incorrectly quitted with superfluous characters filled to command
> line input:
> 
> >  *** U-Boot Boot Menu ***
> >
> >      1. Startup system (Default)
> >      2. Upgrade firmware
> >      3. Upgrade ATF BL2
> >      4. Upgrade ATF FIP
> >      5. Load image
> >      0. U-Boot console
> >
> >
> >  Press UP/DOWN to move, ENTER to select, ESC to quit
> >MT7988> [B
> 
> Analysis shows it was caused by the wrong logic of bootmenu_loop:
> 
> At first the bootmenu_loop received the first ESC char correctly.
> 
> However, during the second call to bootmenu_loop, there's no data
> in the UART Rx FIFO. Due to the low baudrate, the second char of
> the down array key sequence hasn't be fully received.
> 
> But bootmenu_loop just did a mdelay(10), and then treated it as a
> single ESC key press event. It didn't even try tstc() again after
> the 10ms timeout.
> 
> This patch fixes this issue by letting bootmenu_loop check tstc()
> twice.
> 
> Tested-By: E Shattow <lucent at gmail.com>
> Signed-off-by: Weijie Gao <weijie.gao at mediatek.com>

Reviewed-by: Daniel Golle <daniel at makrotopia.org>
Tested-by: Daniel Golle <daniel at makrotopia.org>

Together with 2/3 and 3/3 this now avoids dropping into the U-Boot shell
as long as the menu is short enough. In case of menus with 8 entries of
more I still manage to drop into shell when holding the arrow down key
before the last item has been reached.
That being said, it's already a very big improvement that this now only
happens when holding down a button traversing over a menu with a high
number of items.


> ---
>  common/menu.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/common/menu.c b/common/menu.c
> index 8cc9bf06d9c..48ab7f0f398 100644
> --- a/common/menu.c
> +++ b/common/menu.c
> @@ -525,14 +525,15 @@ enum bootmenu_key bootmenu_loop(struct bootmenu_data *menu,
>  				struct cli_ch_state *cch)
>  {
>  	enum bootmenu_key key;
> -	int c;
> +	int c, errchar = 0;
>  
>  	c = cli_ch_process(cch, 0);
>  	if (!c) {
>  		while (!c && !tstc()) {
>  			schedule();
>  			mdelay(10);
> -			c = cli_ch_process(cch, -ETIMEDOUT);
> +			c = cli_ch_process(cch, errchar);
> +			errchar = -ETIMEDOUT;
>  		}
>  		if (!c) {
>  			c = getchar();
> -- 
> 2.45.2
>