Fix for bug 6691452

Hand merge from ics-aah

> Fix for bug 6691452 : DO NOT MERGE
>
> As it so happens, there seem to be panels out there who disapprove of
> sudden changes in their HDMI clock rate.  In particular, Sony LCD
> panels made from around 2010-2011 (including the Sony GTV panel) seem
> to dislike this behavior.  When exposed to a large jump in the clock
> rate (say from -100pmm to +100ppm in about 30mSec), they seem to
> panic, blank their audio and video, and then resync.  The whole
> panic process takes about 2 seconds.
>
> The HDMI spec says that its clock jitter requirements are defined by
> their differential signalling eye diagram requirements relative to an
> "Ideal Recovery Clock" (see section 4.2.3.1 of the HDMI 1.3a spec).
> Basically, if you pass the eye diagram tests, you pass the clock
> jitter requirements.  We have determined in lab that even being
> extremely aggressive in our VCXO rate changes does not come even close
> to violating the HDMI eye diagrams.  Its just this era of Sony panels
> which seem to be upset by this behavior.
>
> One way or the other, experiments which the GTV devices have seemed to
> indicate that a full range sweep of the VCXO done in 10mSec steps over
> anything faster than 190mSec can cause trouble.  Adding a healthy
> degree of margin to this finding, the fix is to limit the rate of VCXO
> control change such that it never goes at a rate faster than
> FullRange/300mSec.
>
> Change flagged as do not merge due to the code structure changes to master.
> This will need to be merged by hand.
>
> Signed-off-by: John Grossman <johngro@google.com>
> Change-Id: Ibfd361fe1cc2cbd4909489e3317fb12e005c6a75

Change-Id: If62f791c826f1145262a6b546b1dc1f9776c37d8
Signed-off-by: John Grossman <johngro@google.com>

7 files changed, 251 insertions, 58 deletions

diff --git a/services/common_time/Android.mk b/services/common_time/Android.mk
index e534d49..0606ab4 100644
--- a/services/common_time/Android.mk
+++ b/services/common_time/Android.mk
@@ -14,7 +14,8 @@ LOCAL_SRC_FILES := \
     common_time_server_packets.cpp \
     clock_recovery.cpp \
     common_clock.cpp \
-    main.cpp
+    main.cpp \
+    utils.cpp
 
 # Uncomment to enable vesbose logging and debug service.
 #TIME_SERVICE_DEBUG=true
diff --git a/services/common_time/clock_recovery.cpp b/services/common_time/clock_recovery.cpp
index 6c98d32..4a5b2ef 100644
--- a/services/common_time/clock_recovery.cpp
+++ b/services/common_time/clock_recovery.cpp
@@ -53,6 +53,21 @@ ClockRecoveryLoop::ClockRecoveryLoop(LocalClock* local_clock,
 
     local_clock_can_slew_ = local_clock_->initCheck() &&
                            (local_clock_->setLocalSlew(0) == OK);
+    tgt_correction_ = 0;
+    cur_correction_ = 0;
+
+    // Precompute the max rate at which we are allowed to change the VCXO
+    // control.
+    uint64_t N = 0x10000ull * 1000ull;
+    uint64_t D = local_clock_->getLocalFreq() * kMinFullRangeSlewChange_mSec;
+    LinearTransform::reduce(&N, &D);
+    while ((N > INT32_MAX) || (D > UINT32_MAX)) {
+        N >>= 1;
+        D >>= 1;
+        LinearTransform::reduce(&N, &D);
+    }
+    time_to_cur_slew_.a_to_b_numer = static_cast<int32_t>(N);
+    time_to_cur_slew_.a_to_b_denom = static_cast<uint32_t>(D);
 
     reset(true, true);
 
@@ -85,6 +100,9 @@ const int64_t ClockRecoveryLoop::panic_thresh_ = 50000;
 const int64_t ClockRecoveryLoop::control_thresh_ = 10000;
 const float ClockRecoveryLoop::COmin = -100.0f;
 const float ClockRecoveryLoop::COmax = 100.0f;
+const uint32_t ClockRecoveryLoop::kMinFullRangeSlewChange_mSec = 300;
+const int ClockRecoveryLoop::kSlewChangeStepPeriod_mSec = 10;
+
 
 void ClockRecoveryLoop::reset(bool position, bool frequency) {
     Mutex::Autolock lock(&lock_);
@@ -144,7 +162,7 @@ bool ClockRecoveryLoop::pushDisciplineEvent(int64_t local_time,
     int64_t observed_common;
     int64_t delta;
     float delta_f, dCO;
-    int32_t correction_cur;
+    int32_t tgt_correction;
 
     if (OK != common_clock_->localToCommon(local_time, &observed_common)) {
         // Since we just checked to make certain that this conversion was valid,
@@ -254,23 +272,20 @@ bool ClockRecoveryLoop::pushDisciplineEvent(int64_t local_time,
 
     // Convert PPM to 16-bit int range. Add some guard band (-0.01) so we
     // don't get fp weirdness.
-    correction_cur = CO * 327.66;
+    tgt_correction = CO * 327.66;
 
     // If there was a change in the amt of correction to use, update the
     // system.
-    if (correction_cur_ != correction_cur) {
-        correction_cur_ = correction_cur;
-        applySlew();
-    }
+    setTargetCorrection_l(tgt_correction);
 
-    LOG_TS("clock_loop %lld %f %f %f %d\n", raw_delta, delta_f, CO, CObias, correction_cur);
+    LOG_TS("clock_loop %lld %f %f %f %d\n", raw_delta, delta_f, CO, CObias, tgt_correction);
 
 #ifdef TIME_SERVICE_DEBUG
     diag_thread_->pushDisciplineEvent(
             local_time,
             observed_common,
             nominal_common_time,
-            correction_cur,
+            tgt_correction,
             rtt);
 #endif
 
@@ -298,24 +313,109 @@ void ClockRecoveryLoop::reset_l(bool position, bool frequency) {
         last_delta_valid_ = false;
         last_delta_ = 0;
         last_delta_f_ = 0.0;
-        correction_cur_ = 0x0;
         CO = 0.0f;
         lastCObias = CObias = 0.0f;
-        applySlew();
+        setTargetCorrection_l(0);
+        applySlew_l();
     }
 
     filter_wr_   = 0;
     filter_full_ = false;
 }
 
-void ClockRecoveryLoop::applySlew() {
+void ClockRecoveryLoop::setTargetCorrection_l(int32_t tgt) {
+    // When we make a change to the slew rate, we need to be careful to not
+    // change it too quickly as it can anger some HDMI sinks out there, notably
+    // some Sony panels from the 2010-2011 timeframe.  From experimenting with
+    // some of these sinks, it seems like swinging from one end of the range to
+    // another in less that 190mSec or so can start to cause trouble.  Adding in
+    // a hefty margin, we limit the system to a full range sweep in no less than
+    // 300mSec.
+    if (tgt_correction_ != tgt) {
+        int64_t now = local_clock_->getLocalTime();
+        status_t res;
+
+        tgt_correction_ = tgt;
+
+        // Set up the transformation to figure out what the slew should be at
+        // any given point in time in the future.
+        time_to_cur_slew_.a_zero = now;
+        time_to_cur_slew_.b_zero = cur_correction_;
+
+        // Make sure the sign of the slope is headed in the proper direction.
+        bool needs_increase = (cur_correction_ < tgt_correction_);
+        bool is_increasing  = (time_to_cur_slew_.a_to_b_numer > 0);
+        if (( needs_increase && !is_increasing) ||
+            (!needs_increase &&  is_increasing)) {
+            time_to_cur_slew_.a_to_b_numer = -time_to_cur_slew_.a_to_b_numer;
+        }
+
+        // Finally, figure out when the change will be finished and start the
+        // slew operation.
+        time_to_cur_slew_.doReverseTransform(tgt_correction_,
+                                             &slew_change_end_time_);
+
+        applySlew_l();
+    }
+}
+
+bool ClockRecoveryLoop::applySlew_l() {
+    bool ret = true;
+
+    // If cur == tgt, there is no ongoing sleq rate change and we are already
+    // finished.
+    if (cur_correction_ == tgt_correction_)
+        goto bailout;
+
     if (local_clock_can_slew_) {
-        local_clock_->setLocalSlew(correction_cur_);
+        int64_t now = local_clock_->getLocalTime();
+        int64_t tmp;
+
+        if (now >= slew_change_end_time_) {
+            cur_correction_ = tgt_correction_;
+            next_slew_change_timeout_.setTimeout(-1);
+        } else {
+            time_to_cur_slew_.doForwardTransform(now, &tmp);
+
+            if (tmp > INT16_MAX)
+                cur_correction_ = INT16_MAX;
+            else if (tmp < INT16_MIN)
+                cur_correction_ = INT16_MIN;
+            else
+                cur_correction_ = static_cast<int16_t>(tmp);
+
+            next_slew_change_timeout_.setTimeout(kSlewChangeStepPeriod_mSec);
+            ret = false;
+        }
+
+        local_clock_->setLocalSlew(cur_correction_);
     } else {
+        // Since we are not actually changing the rate of a HW clock, we don't
+        // need to worry to much about changing the slew rate so fast that we
+        // anger any downstream HDMI devices.
+        cur_correction_ = tgt_correction_;
+        next_slew_change_timeout_.setTimeout(-1);
+
         // The SW clock recovery implemented by the common clock class expects
         // values expressed in PPM. CO is in ppm.
         common_clock_->setSlew(local_clock_->getLocalTime(), CO);
     }
+
+bailout:
+    return ret;
+}
+
+int ClockRecoveryLoop::applyRateLimitedSlew() {
+    Mutex::Autolock lock(&lock_);
+
+    int ret = next_slew_change_timeout_.msecTillTimeout();
+    if (!ret) {
+        if (applySlew_l())
+            next_slew_change_timeout_.setTimeout(-1);
+        ret = next_slew_change_timeout_.msecTillTimeout();
+    }
+
+    return ret;
 }
 
 }  // namespace android
diff --git a/services/common_time/clock_recovery.h b/services/common_time/clock_recovery.h
index b7362be..20fbf96 100644
--- a/services/common_time/clock_recovery.h
+++ b/services/common_time/clock_recovery.h
@@ -26,6 +26,8 @@
 #include "diag_thread.h"
 #endif
 
+#include "utils.h"
+
 namespace android {
 
 class CommonClock;
@@ -42,6 +44,11 @@ class ClockRecoveryLoop {
                              int64_t data_point_rtt);
     int32_t getLastErrorEstimate();
 
+    // Applies the next step in any ongoing slew change operation.  Returns a
+    // timeout suitable for use with poll/select indicating the number of mSec
+    // until the next change should be applied.
+    int applyRateLimitedSlew();
+
   private:
 
     // Tuned using the "Good Gain" method.
@@ -87,7 +94,8 @@ class ClockRecoveryLoop {
     static uint32_t findMinRTTNdx(DisciplineDataPoint* data, uint32_t count);
 
     void reset_l(bool position, bool frequency);
-    void applySlew();
+    void setTargetCorrection_l(int32_t tgt);
+    bool applySlew_l();
 
     // The local clock HW abstraction we use as the basis for common time.
     LocalClock* local_clock_;
@@ -104,7 +112,11 @@ class ClockRecoveryLoop {
     int32_t last_delta_;
     float last_delta_f_;
     int32_t integrated_error_;
-    int32_t correction_cur_;
+    int32_t tgt_correction_;
+    int32_t cur_correction_;
+    LinearTransform time_to_cur_slew_;
+    int64_t slew_change_end_time_;
+    Timeout next_slew_change_timeout_;
 
     // Contoller Output.
     float CO;
@@ -128,6 +140,15 @@ class ClockRecoveryLoop {
     DisciplineDataPoint startup_filter_data_[kStartupFilterSize];
     uint32_t startup_filter_wr_;
 
+    // Minimum number of milliseconds over which we allow a full range change
+    // (from rail to rail) of the VCXO control signal.  This is the rate
+    // limiting factor which keeps us from changing the clock rate so fast that
+    // we get in trouble with certain HDMI sinks.
+    static const uint32_t kMinFullRangeSlewChange_mSec;
+
+    // How much time (in msec) to wait 
+    static const int kSlewChangeStepPeriod_mSec;
+
 #ifdef TIME_SERVICE_DEBUG
     sp<DiagThread> diag_thread_;
 #endif
diff --git a/services/common_time/common_time_server.cpp b/services/common_time/common_time_server.cpp
index 7a4986b..4e5d16e 100644
--- a/services/common_time/common_time_server.cpp
+++ b/services/common_time/common_time_server.cpp
@@ -202,9 +202,11 @@ bool CommonTimeServer::runStateMachine_l() {
     // run the state machine
     while (!exitPending()) {
         struct pollfd pfds[2];
-        int rc;
+        int rc, timeout;
         int eventCnt = 0;
         int64_t wakeupTime;
+        uint32_t t1, t2;
+        bool needHandleTimeout = false;
 
         // We are always interested in our wakeup FD.
         pfds[eventCnt].fd      = mWakeupThreadFD;
@@ -221,10 +223,14 @@ bool CommonTimeServer::runStateMachine_l() {
             eventCnt++;
         }
 
+        t1 = static_cast<uint32_t>(mCurTimeout.msecTillTimeout());
+        t2 = static_cast<uint32_t>(mClockRecovery.applyRateLimitedSlew());
+        timeout = static_cast<int>(t1 < t2 ? t1 : t2);
+
         // Note, we were holding mLock when this function was called.  We
         // release it only while we are blocking and hold it at all other times.
         mLock.unlock();
-        rc          = poll(pfds, eventCnt, mCurTimeout.msecTillTimeout());
+        rc          = poll(pfds, eventCnt, timeout);
         wakeupTime  = mLocalClock.getLocalTime();
         mLock.lock();
 
@@ -238,8 +244,11 @@ bool CommonTimeServer::runStateMachine_l() {
             return false;
         }
 
-        if (rc == 0)
-            mCurTimeout.setTimeout(kInfiniteTimeout);
+        if (rc == 0) {
+            needHandleTimeout = !mCurTimeout.msecTillTimeout();
+            if (needHandleTimeout)
+                mCurTimeout.setTimeout(kInfiniteTimeout);
+        }
 
         // Were we woken up on purpose?  If so, clear the eventfd with a read.
         if (pfds[0].revents)
@@ -336,9 +345,8 @@ bool CommonTimeServer::runStateMachine_l() {
             continue;
         }
 
-        // Did we wakeup with no signalled events across all of our FDs?  If so,
-        // we must have hit our timeout.
-        if (rc == 0) {
+        // Time to handle the timeouts?
+        if (needHandleTimeout) {
             if (!handleTimeout())
                 ALOGE("handleTimeout failed");
             continue;
@@ -1326,29 +1334,6 @@ bool CommonTimeServer::sockaddrMatch(const sockaddr_storage& a1,
     }
 }
 
-void CommonTimeServer::TimeoutHelper::setTimeout(int msec) {
-    mTimeoutValid = (msec >= 0);
-    if (mTimeoutValid)
-        mEndTime = systemTime() +
-                   (static_cast<nsecs_t>(msec) * 1000000);
-}
-
-int CommonTimeServer::TimeoutHelper::msecTillTimeout() {
-    if (!mTimeoutValid)
-        return kInfiniteTimeout;
-
-    nsecs_t now = systemTime();
-    if (now >= mEndTime)
-        return 0;
-
-    uint64_t deltaMsec = (((mEndTime - now) + 999999) / 1000000);
-
-    if (deltaMsec > static_cast<uint64_t>(MAX_INT))
-        return MAX_INT;
-
-    return static_cast<int>(deltaMsec);
-}
-
 bool CommonTimeServer::shouldPanicNotGettingGoodData() {
     if (mClient_FirstSyncTX) {
         int64_t now = mLocalClock.getLocalTime();
diff --git a/services/common_time/common_time_server.h b/services/common_time/common_time_server.h
index a0f549f..b2ad3f0 100644
--- a/services/common_time/common_time_server.h
+++ b/services/common_time/common_time_server.h
@@ -28,6 +28,7 @@
 #include "clock_recovery.h"
 #include "common_clock.h"
 #include "common_time_server_packets.h"
+#include "utils.h"
 
 #define RTT_LOG_SIZE 30
 
@@ -104,18 +105,6 @@ class CommonTimeServer : public Thread {
         int64_t rxTimes[RTT_LOG_SIZE];
     };
 
-    class TimeoutHelper {
-      public:
-        TimeoutHelper() : mTimeoutValid(false) { }
-
-        void setTimeout(int msec);
-        int msecTillTimeout();
-
-      private:
-        bool        mTimeoutValid;
-        nsecs_t     mEndTime;
-    };
-
     bool threadLoop();
 
     bool runStateMachine_l();
@@ -194,7 +183,7 @@ class CommonTimeServer : public Thread {
     bool shouldPanicNotGettingGoodData();
 
     // Helper to keep track of the state machine's current timeout
-    TimeoutHelper mCurTimeout;
+    Timeout mCurTimeout;
 
     // common clock, local clock abstraction, and clock recovery loop
     CommonClock mCommonClock;
diff --git a/services/common_time/utils.cpp b/services/common_time/utils.cpp
new file mode 100644
index 0000000..3ed2599
--- /dev/null
+++ b/services/common_time/utils.cpp
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "utils.h"
+
+namespace android {
+
+void Timeout::setTimeout(int msec) {
+    if (msec < 0) {
+        mSystemEndTime = 0;
+        return;
+    }
+
+    mSystemEndTime = systemTime() + (static_cast<nsecs_t>(msec) * 1000000);
+}
+
+int Timeout::msecTillTimeout(nsecs_t nowTime) {
+    if (!mSystemEndTime) {
+        return -1;
+    }
+
+    if (mSystemEndTime < nowTime) {
+        return 0;
+    }
+
+    nsecs_t delta = mSystemEndTime - nowTime;
+    delta += 999999;
+    delta /= 1000000;
+    if (delta > 0x7FFFFFFF) {
+        return 0x7FFFFFFF;
+    }
+
+    return static_cast<int>(delta);
+}
+
+}  // namespace android
diff --git a/services/common_time/utils.h b/services/common_time/utils.h
new file mode 100644
index 0000000..d3545c9
--- /dev/null
+++ b/services/common_time/utils.h
@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef __UTILS_H__
+#define __UTILS_H__
+
+#include <stdint.h>
+#include <unistd.h>
+
+#include <utils/Timers.h>
+
+namespace android {
+
+class Timeout {
+  public:
+    Timeout() : mSystemEndTime(0) { }
+
+    // Set a timeout which should occur msec milliseconds from now.
+    // Negative values will cancel any current timeout;
+    void setTimeout(int msec);
+
+    // Return the number of milliseconds until the timeout occurs, or -1 if
+    // no timeout is scheduled.
+    int msecTillTimeout(nsecs_t nowTime);
+    int msecTillTimeout() { return msecTillTimeout(systemTime()); }
+
+  private:
+    // The systemTime() at which the timeout will be complete, or 0 if no
+    // timeout is currently scheduled.
+    nsecs_t mSystemEndTime;
+};
+
+}  // namespace android
+
+#endif  // __UTILS_H__