From 0a1dcacbfded8ab5f0468d6eeed40b334e09d656 Mon Sep 17 00:00:00 2001
From: tmk <hasu@tmk-kbd.com>
Date: Fri, 5 Feb 2021 23:46:18 +0900
Subject: [PATCH] ibmpc: Fix ACK check in host_send() for Z-150 AT #661

Zenith Z-150 AT doesn't seems to place ACK signaling normally.
https://github.com/tmk/tmk_keyboard/issues/661#issue-743168434
https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#zenith-z-150-beige

IBM genuine PC host checks data line only, not clock on ACK. In this
case Z-150 AT ACK signaling can be handled.
http://www.halicery.com/Hardware/Intel%208042%20and%208048/8042_PS2_INTERN.TEXT (026C:)
http://halicery.com/8042/8042_1503033.TXT (0274:)

Place 'inhibit' on lines for long enough to cancel current state and
recovery from ERROR but not sure this really helps.
---
 tmk_core/protocol/ibmpc.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/tmk_core/protocol/ibmpc.c b/tmk_core/protocol/ibmpc.c
index 0e94e301..73439c62 100644
--- a/tmk_core/protocol/ibmpc.c
+++ b/tmk_core/protocol/ibmpc.c
@@ -135,18 +135,12 @@ int16_t ibmpc_host_send(uint8_t data)
     /* Stop bit */
     wait_us(15);
     data_hi();
-    WAIT(clock_hi, 50, 6);
-    if (ibmpc_protocol == IBMPC_PROTOCOL_AT_Z150) { goto RECV; }
-    WAIT(clock_lo, 50, 7);
 
     /* Ack */
-    WAIT(data_lo, 50, 8);
+    WAIT(data_lo, 300, 6);
+    WAIT(data_hi, 300, 7);
+    WAIT(clock_hi, 300, 8);
 
-    /* wait for idle state */
-    WAIT(clock_hi, 50, 9);
-    WAIT(data_hi, 50, 10);
-
-RECV:
     // clear buffer to get response correctly
     recv_data = 0xFFFF;
     ibmpc_host_isr_clear();
@@ -156,6 +150,8 @@ RECV:
     return ibmpc_host_recv_response();
 ERROR:
     ibmpc_error |= IBMPC_ERR_SEND;
+    inhibit();
+    wait_ms(2);
     idle();
     IBMPC_INT_ON();
     return -1;