diff options
Diffstat (limited to 'chip')
| -rw-r--r-- | chip/npcx/lpc.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/chip/npcx/lpc.c b/chip/npcx/lpc.c index 8572ce497d..b287ad8c36 100644 --- a/chip/npcx/lpc.c +++ b/chip/npcx/lpc.c @@ -518,11 +518,19 @@ static void handle_host_write(int is_cmd) /* KB controller input buffer full ISR */ void lpc_kbc_ibf_interrupt(void) { + uint8_t status; uint8_t ibf; /* If "command" input 0, else 1*/ if (lpc_keyboard_input_pending()) { + /* + * Reading HIKMDI causes the IBF flag to deassert and allows + * the host to write a new byte into the input buffer. So if we + * don't capture the status before reading HIKMDI we will race + * with the host and get an invalid value for HIKMST.A20. + */ + status = NPCX_HIKMST; ibf = NPCX_HIKMDI; - keyboard_host_write(ibf, (NPCX_HIKMST & 0x08) ? 1 : 0); + keyboard_host_write(ibf, (status & 0x08) ? 1 : 0); CPRINTS("ibf isr %02x", ibf); task_wake(TASK_ID_KEYPROTO); } else { |