input: Flush the keyboard buffer before resetting it

If U-Boot is not the first-stage bootloader the keyboard may already be
set up. Make sure to flush any data before trying to reset it. This
avoids a long timeout / hang.

Add some comments and a log category while we are here.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

diff --git a/drivers/input/i8042.c b/drivers/input/i8042.c
index 3563dc98838fd7234f6090a6e85835714d76bec4..e6070ca015296b29d618e31fb123669786f2d5e8 100644 (file)
--- a/drivers/input/i8042.c
+++ b/drivers/input/i8042.c
@@ -6,6 +6,8 @@
 
 /* i8042.c - Intel 8042 keyboard driver routines */
 
+#define LOG_CATEGORY UCLASS_KEYBOARD
+
 #include <common.h>
 #include <dm.h>
 #include <env.h>
@@ -54,6 +56,14 @@ static unsigned char ext_key_map[] = {
        0x00  /* map end */
        };
 
+/**
+ * kbd_input_empty() - Wait until the keyboard is ready for a command
+ *
+ * Checks the IBF flag (input buffer full), waiting for it to indicate that
+ * any previous command has been processed.
+ *
+ * Return: true if ready, false if it timed out
+ */
 static int kbd_input_empty(void)
 {
        int kbd_timeout = KBD_TIMEOUT * 1000;
@@ -64,6 +74,12 @@ static int kbd_input_empty(void)
        return kbd_timeout != -1;
 }
 
+/**
+ * kbd_output_full() - Wait until the keyboard has data available
+ *
+ * Checks the OBF flag (output buffer full), waiting for it to indicate that
+ * a response to a previous command is available
+ */
 static int kbd_output_full(void)
 {
        int kbd_timeout = KBD_TIMEOUT * 1000;
@@ -127,6 +143,9 @@ static int kbd_reset(int quirk)
 {
        int config;
 
+       if (!kbd_input_empty())
+               goto err;
+
        /* controller self test */
        if (kbd_cmd_read(CMD_SELF_TEST) != KBC_TEST_OK)
                goto err;