diff options
| -rw-r--r-- | chip/lm4/lpc.c | 6 | ||||
| -rw-r--r-- | util/comm-lpc.c | 19 |
2 files changed, 12 insertions, 13 deletions
diff --git a/chip/lm4/lpc.c b/chip/lm4/lpc.c index 587c79c22a..8a99247c74 100644 --- a/chip/lm4/lpc.c +++ b/chip/lm4/lpc.c @@ -724,6 +724,12 @@ static void lpc_init(void) */ LM4_LPC_ADR(LPC_CH_CMD) = EC_LPC_ADDR_HOST_DATA; LM4_LPC_CTL(LPC_CH_CMD) = (LPC_POOL_OFFS_CMD << (5 - 1)); + /* + * Initialize status bits to 0. We never set the ACPI burst status bit, + * so this guarantees that at least one status bit will always be 0. + * This is used by comm_lpc.c to detect that the EC is present on the + * LPC bus. See crosbug.com/p/10963. + */ LM4_LPC_ST(LPC_CH_CMD) = 0; /* Unmask interrupt for host command writes */ LM4_LPC_LPCIM |= LM4_LPC_INT_MASK(LPC_CH_CMD, 4); diff --git a/util/comm-lpc.c b/util/comm-lpc.c index adbbb89f10..8ea4e9ddd8 100644 --- a/util/comm-lpc.c +++ b/util/comm-lpc.c @@ -257,22 +257,15 @@ int comm_init_lpc(void) /* * Test if the I/O port has been configured for Chromium EC LPC - * interface. If all the bytes are 0xff, very likely that Chromium EC - * is not present. - * - * TODO: (crosbug.com/p/10963) Should only need to look at the command - * byte, since we don't support ACPI burst mode and thus bit 4 should - * be 0. + * interface. Chromium EC guarantees that at least one status bit will + * be 0, so if the command and data bytes are both 0xff, very likely + * that Chromium EC is not present. See crosbug.com/p/10963. */ byte &= inb(EC_LPC_ADDR_HOST_CMD); byte &= inb(EC_LPC_ADDR_HOST_DATA); - for (i = 0; i < EC_PROTO2_MAX_PARAM_SIZE && byte == 0xff; ++i) - byte &= inb(EC_LPC_ADDR_HOST_PARAM + i); if (byte == 0xff) { - fprintf(stderr, "Port 0x%x,0x%x,0x%x-0x%x are all 0xFF.\n", - EC_LPC_ADDR_HOST_CMD, EC_LPC_ADDR_HOST_DATA, - EC_LPC_ADDR_HOST_PARAM, - EC_LPC_ADDR_HOST_PARAM + EC_PROTO2_MAX_PARAM_SIZE - 1); + fprintf(stderr, "Port 0x%x,0x%x are both 0xFF.\n", + EC_LPC_ADDR_HOST_CMD, EC_LPC_ADDR_HOST_DATA); fprintf(stderr, "Very likely this board doesn't have a Chromium EC.\n"); return -4; @@ -304,7 +297,7 @@ int comm_init_lpc(void) sizeof(struct ec_host_response); } else if (i & EC_HOST_CMD_FLAG_LPC_ARGS_SUPPORTED) { - /* Protocol version 2*/ + /* Protocol version 2 */ ec_command = ec_command_lpc; ec_max_outsize = ec_max_insize = EC_PROTO2_MAX_PARAM_SIZE; |