[PATCH] menu: fix the logic checking whether ESC key is pressed

[Weijie Gao]

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.

Signed-off-by: Weijie Gao <weijie.gao at mediatek.com>
---
 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();
-- 
2.17.0