From 84f7eb85cc7b5ed9c1a31c4eaaab8edebac9b4ad Mon Sep 17 00:00:00 2001
From: Simon Rettberg
Date: Wed, 14 Sep 2022 10:39:17 +0200
Subject: Fix TMDS clock limiting if DTD info is missing (Default to 165MHz)

---
 src/xprivate.cpp | 35 +++++++++++++++++------------------
 1 file changed, 17 insertions(+), 18 deletions(-)

diff --git a/src/xprivate.cpp b/src/xprivate.cpp
index afdf32d..3aea9b5 100644
--- a/src/xprivate.cpp
+++ b/src/xprivate.cpp
@@ -47,15 +47,14 @@ static int modeEqual(const XRRModeInfo *a, const XRRModeInfo *b)
 {
 	return (a->width == b->width &&
 		a->height == b->height &&
-		a->dotClock / 10 == b->dotClock / 10 &&
+		a->dotClock / 100 == b->dotClock / 100 &&
 		a->hSyncStart == b->hSyncStart &&
 		a->hSyncEnd == b->hSyncEnd &&
 		a->hTotal == b->hTotal &&
 		a->hSkew == b->hSkew &&
 		a->vSyncStart == b->vSyncStart &&
 		a->vSyncEnd == b->vSyncEnd &&
-		a->vTotal == b->vTotal &&
-		a->modeFlags == b->modeFlags);
+		a->vTotal == b->vTotal);
 }
 
 static int errorHandler(Display *dpy, XErrorEvent *err)
@@ -291,6 +290,9 @@ void XPrivate::addMissingEdidResolutions()
             if (maxClock != 0)
                 break;
         }
+        if (maxClock <= 0) {
+            maxClock = 165;
+        }
         qDebug() << "Standard block DTD for output" << resptr->outputs[i] << "aka" << _outputMap[resptr->outputs[i]]->outputName
                  << "MaxClock" << maxClock << "MHz";
         for (unsigned int j = 54; j < 125; j+= 18) {
@@ -434,12 +436,7 @@ void XPrivate::addMissingModesFromDtd(XRRScreenResources *res, RROutput outputId
 	m.vSyncEnd  = static_cast<unsigned int>(vactive + vsyncoff + vsyncwidth);
 	m.vTotal    = static_cast<unsigned int>(vactive + vblank);
 	m.id        = 0;
-	m.name = buf;
-	refresh = static_cast<int>(m.dotClock / (m.hTotal * m.vTotal));
-	m.nameLength = static_cast<unsigned int>(snprintf(buf, sizeof(buf), "%dx%d_%d", hactive, vactive, refresh));
-	if (m.nameLength > sizeof(buf)) {
-		m.nameLength = sizeof(buf);
-	}
+	// m.name gets set after we potentially limit the Hz down below
 	if ((data[17] & 0x18) == 0x18) {
 		// Digital Separate
 		if (data[17] & 0x04) {
@@ -467,13 +464,8 @@ void XPrivate::addMissingModesFromDtd(XRRScreenResources *res, RROutput outputId
 		m.modeFlags |= RR_Interlace;
 	}
 	RRMode modeId = 0;
-	// More special case B/S: So, X11 mysteriously ignores a couple of resolutions, sometimes.
-	// Curiously, this happens with a Philips TV, but not an LG TV. EDID dump looks very similar
-	// on both. More curiously, in Xorg.log, the first time the modelines for the Philips TV get dumped,
-	// the 4k resolution is missing, even though it's in the EDID dump from right before those lines.
-	// Then the xserver logs the modelines for the Philips TV a couple more times, and every time the 4k
-	// resolution is in the list. Just not the first time. However, the resolutions never get added to
-	// the TV.
+	// Kernel might have wrongly identified a DP++ adapter as type 1, limiting TMDS to 165MHz, we ignore this and
+	// hope for the best.
 	if (m.dotClock > maxClockMhz * 1000000) {
 		for (int mode = 0; mode < res->nmode; ++mode) {
 			if (res->modes[mode].width == m.width && res->modes[mode].height == m.height && res->modes[mode].dotClock <= maxClockMhz * 1000000) {
@@ -494,6 +486,13 @@ void XPrivate::addMissingModesFromDtd(XRRScreenResources *res, RROutput outputId
 			qDebug() << "Capping to" << refresh << "Hz, " << (m.dotClock / 1000000) << "MHz";
 		}
 	}
+	// Now set name
+	m.name = buf;
+	refresh = static_cast<int>(m.dotClock / (m.hTotal * m.vTotal));
+	m.nameLength = static_cast<unsigned int>(snprintf(buf, sizeof(buf), "%dx%d_%d", hactive, vactive, refresh));
+	if (m.nameLength > sizeof(buf)) {
+		m.nameLength = sizeof(buf);
+	}
 	// See if we should add this mode
 	if (modeId == 0) {
 		for (int mode = 0; mode < res->nmode; ++mode) {
@@ -505,13 +504,13 @@ void XPrivate::addMissingModesFromDtd(XRRScreenResources *res, RROutput outputId
 		}
 	}
 	if (modeId == 0) {
-		qDebug() << "Creating" << m.name << "for output" << outputId << m.width << "x" << m.height << "@" << (m.dotClock / 1000000);
+		qDebug() << "Creating" << m.name << "for output" << outputId << m.width << "x" << m.height << "@" << (m.dotClock / 1000000) << "MHz";
 		qDebug() << m.hSyncStart << m.hSyncEnd << m.hTotal;
 		qDebug() << m.vSyncStart << m.vSyncEnd << m.vTotal;
 		modeId = XRRCreateMode(_display, DefaultRootWindow(_display), &m);
 	}
 	if (modeId != 0) {
-		qDebug() << "Adding mode for output" << outputId << m.width << "x" << m.height << "@" << (m.dotClock / 1000000);
+		qDebug() << "Adding mode for output" << outputId << m.width << "x" << m.height << "@" << (m.dotClock / 1000000) << "MHz";
 		XRRAddOutputMode(_display, outputId, modeId);
 	} else {
 		qDebug() << "Failed to add" << buf << "to" << outputId << "- mode not found/created";
-- 
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