pd: Refine HPD debounce values.

Change refines HPD debounce values into both upstream and downstream
values for packetizing across the type-C link.

For LVL, the upstream type-C device will packetize any HPD transition
>=2ms as either HIGH or LOW.  On the downstream side the value is
driven immediately.  Additional debouncing should be done by true
upstream device according to specification.

For IRQ, the upstream type-C device will packetize any HPD pulse
>250usec as an IRQ.  On the downstream side it will be de-packetized
to create 750usec pulse.

Signed-off-by: Todd Broch <tbroch@chromium.org>

BRANCH=samus
BUG=chrome-os-partner:39717
TEST=samus|macbook(2015) + hoho|dingdong|apple HDMI type-C dongles
still drive screens successfully.

Change-Id: Ide58f3b2d675a82c12ca6afc2be53ca6e2561ace
Reviewed-on: https://chromium-review.googlesource.com/273867
Reviewed-by: Alec Berg <alecaberg@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
Commit-Queue: Todd Broch <tbroch@chromium.org>
Tested-by: Todd Broch <tbroch@chromium.org>

6 files changed, 40 insertions, 35 deletions

diff --git a/board/dingdong/board.c b/board/dingdong/board.c
index cdeb95342c..2896135389 100644
--- a/board/dingdong/board.c
+++ b/board/dingdong/board.c
@@ -34,16 +34,16 @@ void hpd_event(enum gpio_signal signal);
  *    3. irq  : downstream display sink signalling an interrupt.
  *
  * The debounce times for these various events are:
- *  100MSEC : min pulse width of level value.
- *    2MSEC : min pulse width of IRQ low pulse.  Max is level debounce min.
+ *   HPD_USTREAM_DEBOUNCE_LVL : min pulse width of level value.
+ *   HPD_USTREAM_DEBOUNCE_IRQ : min pulse width of IRQ low pulse.
  *
  * lvl(n-2) lvl(n-1)  lvl   prev_delta  now_delta event
  * ----------------------------------------------------
- * 1        0         1     <2ms        n/a       low glitch (ignore)
- * 1        0         1     >2ms        <100ms    irq
- * x        0         1     n/a         >100ms    high
- * 0        1         0     <100ms      n/a       high glitch (ignore)
- * x        1         0     n/a         >100ms    low
+ * 1        0         1     <IRQ        n/a       low glitch (ignore)
+ * 1        0         1     >IRQ        <LVL      irq
+ * x        0         1     n/a         >LVL      high
+ * 0        1         0     <LVL        n/a       high glitch (ignore)
+ * x        1         0     n/a         >LVL      low
  */
 
 void hpd_irq_deferred(void)
@@ -77,14 +77,15 @@ void hpd_event(enum gpio_signal signal)
 	hook_call_deferred(hpd_lvl_deferred, -1);
 
 	/* It's a glitch.  Previous time moves but level is the same. */
-	if (cur_delta < HPD_DEBOUNCE_IRQ)
+	if (cur_delta < HPD_USTREAM_DEBOUNCE_IRQ)
 		return;
 
-	if ((!hpd_prev_level && level) && (cur_delta < HPD_DEBOUNCE_LVL))
+	if ((!hpd_prev_level && level) &&
+	    (cur_delta < HPD_USTREAM_DEBOUNCE_LVL))
 		/* It's an irq */
 		hook_call_deferred(hpd_irq_deferred, 0);
-	else if (cur_delta >= HPD_DEBOUNCE_LVL)
-		hook_call_deferred(hpd_lvl_deferred, HPD_DEBOUNCE_LVL);
+	else if (cur_delta >= HPD_USTREAM_DEBOUNCE_LVL)
+		hook_call_deferred(hpd_lvl_deferred, HPD_USTREAM_DEBOUNCE_LVL);
 
 	hpd_prev_level = level;
 }
diff --git a/board/hoho/board.c b/board/hoho/board.c
index 19f0cc2f7c..8e0a370bf3 100644
--- a/board/hoho/board.c
+++ b/board/hoho/board.c
@@ -36,16 +36,16 @@ void hpd_event(enum gpio_signal signal);
  *    3. irq  : downstream display sink signalling an interrupt.
  *
  * The debounce times for these various events are:
- *  100MSEC : min pulse width of level value.
- *    2MSEC : min pulse width of IRQ low pulse.  Max is level debounce min.
+ *   HPD_USTREAM_DEBOUNCE_LVL : min pulse width of level value.
+ *   HPD_USTREAM_DEBOUNCE_IRQ : min pulse width of IRQ low pulse.
  *
  * lvl(n-2) lvl(n-1)  lvl   prev_delta  now_delta event
  * ----------------------------------------------------
- * 1        0         1     <2ms        n/a       low glitch (ignore)
- * 1        0         1     >2ms        <100ms    irq
- * x        0         1     n/a         >100ms    high
- * 0        1         0     <100ms      n/a       high glitch (ignore)
- * x        1         0     n/a         >100ms    low
+ * 1        0         1     <IRQ        n/a       low glitch (ignore)
+ * 1        0         1     >IRQ        <LVL      irq
+ * x        0         1     n/a         >LVL      high
+ * 0        1         0     <LVL        n/a       high glitch (ignore)
+ * x        1         0     n/a         >LVL      low
  */
 
 void hpd_irq_deferred(void)
@@ -79,14 +79,15 @@ void hpd_event(enum gpio_signal signal)
 	hook_call_deferred(hpd_lvl_deferred, -1);
 
 	/* It's a glitch.  Previous time moves but level is the same. */
-	if (cur_delta < HPD_DEBOUNCE_IRQ)
+	if (cur_delta < HPD_USTREAM_DEBOUNCE_IRQ)
 		return;
 
-	if ((!hpd_prev_level && level) && (cur_delta < HPD_DEBOUNCE_LVL))
+	if ((!hpd_prev_level && level) &&
+	    (cur_delta < HPD_USTREAM_DEBOUNCE_LVL))
 		/* It's an irq */
 		hook_call_deferred(hpd_irq_deferred, 0);
-	else if (cur_delta >= HPD_DEBOUNCE_LVL)
-		hook_call_deferred(hpd_lvl_deferred, HPD_DEBOUNCE_LVL);
+	else if (cur_delta >= HPD_USTREAM_DEBOUNCE_LVL)
+		hook_call_deferred(hpd_lvl_deferred, HPD_USTREAM_DEBOUNCE_LVL);
 
 	hpd_prev_level = level;
 }
diff --git a/board/plankton/board.c b/board/plankton/board.c
index 40b0c2b2d8..64f23549ec 100644
--- a/board/plankton/board.c
+++ b/board/plankton/board.c
@@ -41,16 +41,16 @@ static int sn75dp130_dpcd_init(void);
  *    3. irq  : downstream display sink signalling an interrupt.
  *
  * The debounce times for these various events are:
- *  100MSEC : min pulse width of level value.
- *    2MSEC : min pulse width of IRQ low pulse.  Max is level debounce min.
+ *   HPD_USTREAM_DEBOUNCE_LVL : min pulse width of level value.
+ *   HPD_USTREAM_DEBOUNCE_IRQ : min pulse width of IRQ low pulse.
  *
  * lvl(n-2) lvl(n-1)  lvl   prev_delta  now_delta event
  * ----------------------------------------------------
- * 1        0         1     <2ms        n/a       low glitch (ignore)
- * 1        0         1     >2ms        <100ms    irq
- * x        0         1     n/a         >100ms    high
- * 0        1         0     <100ms      n/a       high glitch (ignore)
- * x        1         0     n/a         >100ms    low
+ * 1        0         1     <IRQ        n/a       low glitch (ignore)
+ * 1        0         1     >IRQ        <LVL      irq
+ * x        0         1     n/a         >LVL      high
+ * 0        1         0     <LVL        n/a       high glitch (ignore)
+ * x        1         0     n/a         >LVL      low
  */
 
 void hpd_lvl_deferred(void)
@@ -84,14 +84,14 @@ void hpd_event(enum gpio_signal signal)
 	uint64_t cur_delta = now.val - hpd_prev_ts;
 
 	/* Record low pulse */
-	if (cur_delta >= HPD_DEBOUNCE_IRQ && level)
+	if (cur_delta >= HPD_USTREAM_DEBOUNCE_IRQ && level)
 		hpd_possible_irq = 1;
 
 	/* store current time */
 	hpd_prev_ts = now.val;
 
 	/* All previous hpd level events need to be re-triggered */
-	hook_call_deferred(hpd_lvl_deferred, HPD_DEBOUNCE_LVL);
+	hook_call_deferred(hpd_lvl_deferred, HPD_USTREAM_DEBOUNCE_LVL);
 }
 
 /* Debounce time for voltage buttons */
diff --git a/board/ryu/usb_pd_policy.c b/board/ryu/usb_pd_policy.c
index c64d59e41c..1bd5c6e6cd 100644
--- a/board/ryu/usb_pd_policy.c
+++ b/board/ryu/usb_pd_policy.c
@@ -338,7 +338,7 @@ static int svdm_dp_attention(int port, uint32_t *payload)
 	if (irq & cur_lvl) {
 		gpio_set_level(GPIO_USBC_DP_HPD, 0);
 		hook_call_deferred(hpd_irq_deferred,
-				   HPD_DEBOUNCE_IRQ);
+				   HPD_DSTREAM_DEBOUNCE_IRQ);
 	} else if (irq & !cur_lvl) {
 		CPRINTF("ERR:HPD:IRQ&LOW\n");
 		return 0; /* nak */
diff --git a/board/samus_pd/usb_pd_policy.c b/board/samus_pd/usb_pd_policy.c
index 154a1303e7..af58c7e004 100644
--- a/board/samus_pd/usb_pd_policy.c
+++ b/board/samus_pd/usb_pd_policy.c
@@ -367,7 +367,7 @@ static int svdm_dp_attention(int port, uint32_t *payload)
 	if (irq & cur_lvl) {
 		gpio_set_level(hpd, 0);
 		hook_call_deferred(PORT_TO_HPD_IRQ_DEFERRED(port),
-				   HPD_DEBOUNCE_IRQ);
+				   HPD_DSTREAM_DEBOUNCE_IRQ);
 	} else if (irq & !cur_lvl) {
 		CPRINTF("ERR:HPD:IRQ&LOW\n");
 		return 0; /* nak */
diff --git a/include/usb_pd.h b/include/usb_pd.h
index 31c3501726..2a432936f4 100644
--- a/include/usb_pd.h
+++ b/include/usb_pd.h
@@ -555,8 +555,11 @@ struct pd_policy {
 #define PD_VDO_DPSTS_HPD_LVL(x) (((x) >> 7) & 1)
 #define PD_VDO_DPSTS_MF_PREF(x) (((x) >> 4) & 1)
 
-#define HPD_DEBOUNCE_LVL (100*MSEC)
-#define HPD_DEBOUNCE_IRQ (2*MSEC)
+/* Per DisplayPort Spec v1.3 Section 3.3 */
+#define HPD_USTREAM_DEBOUNCE_LVL (2*MSEC)
+#define HPD_USTREAM_DEBOUNCE_IRQ (250)
+#define HPD_DSTREAM_DEBOUNCE_IRQ (750)  /* between 500-1000us */
+
 /*
  * DisplayPort Configure VDO
  * -------------------------