From 1768af38c737f4c14d32f587b51a8ec3d3d6ed5f Mon Sep 17 00:00:00 2001
From: Adam Jackson <ajax@redhat.com>
Date: Thu, 13 Dec 2007 15:06:18 -0500
Subject: [PATCH] Add infrastructure for validating modes by memory bandwidth.

---
 hw/xfree86/common/xf86Mode.c |  2 ++
 hw/xfree86/common/xf86str.h  |  1 +
 hw/xfree86/modes/xf86Modes.c | 37 ++++++++++++++++++++++++++++++++++++
 hw/xfree86/modes/xf86Modes.h |  5 +++++
 4 files changed, 45 insertions(+)

diff --git a/hw/xfree86/common/xf86Mode.c b/hw/xfree86/common/xf86Mode.c
index 544276bdf..782f08b8d 100644
--- a/hw/xfree86/common/xf86Mode.c
+++ b/hw/xfree86/common/xf86Mode.c
@@ -183,6 +183,8 @@ xf86ModeStatusToString(ModeStatus status)
         return "all modes must have the same resolution";
     case MODE_NO_REDUCED:
         return "monitor doesn't support reduced blanking";
+    case MODE_BANDWIDTH:
+	return "mode requires too much memory bandwidth";
     case MODE_BAD:
 	return "unknown reason";
     case MODE_ERROR:
diff --git a/hw/xfree86/common/xf86str.h b/hw/xfree86/common/xf86str.h
index af98b4fd5..2e0213597 100644
--- a/hw/xfree86/common/xf86str.h
+++ b/hw/xfree86/common/xf86str.h
@@ -125,6 +125,7 @@ typedef enum {
     MODE_ONE_HEIGHT,    /* only one height is supported */
     MODE_ONE_SIZE,      /* only one resolution is supported */
     MODE_NO_REDUCED,    /* monitor doesn't accept reduced blanking */
+    MODE_BANDWIDTH,	/* mode requires too much memory bandwidth */
     MODE_BAD = -2,	/* unspecified reason */
     MODE_ERROR	= -1	/* error condition */
 } ModeStatus;
diff --git a/hw/xfree86/modes/xf86Modes.c b/hw/xfree86/modes/xf86Modes.c
index 12ee6e05b..3febd3759 100644
--- a/hw/xfree86/modes/xf86Modes.c
+++ b/hw/xfree86/modes/xf86Modes.c
@@ -118,6 +118,24 @@ xf86ModeHeight (DisplayModePtr mode, Rotation rotation)
     }
 }
 
+/** Calculates the memory bandwidth (in MiB/sec) of a mode. */
+_X_EXPORT unsigned int
+xf86ModeBandwidth(DisplayModePtr mode, int depth)
+{
+    float a_active, a_total, active_percent, pixels_per_second;
+    int bytes_per_pixel = (depth + 7) / 8;
+
+    if (!mode->HTotal || !mode->VTotal || !mode->Clock)
+	return 0;
+
+    a_active = mode->HDisplay * mode->VDisplay;
+    a_total = mode->HTotal * mode->VTotal;
+    active_percent = a_active / a_total;
+    pixels_per_second = active_percent * mode->Clock * 1000.0;
+
+    return (unsigned int)(pixels_per_second * bytes_per_pixel / (1024 * 1024));
+}
+
 /** Sets a default mode name of <width>x<height> on a mode. */
 _X_EXPORT void
 xf86SetModeDefaultName(DisplayModePtr mode)
@@ -485,6 +503,25 @@ xf86ValidateModesUserConfig(ScrnInfoPtr pScrn, DisplayModePtr modeList)
 }
 
 
+/**
+ * Marks as bad any modes exceeding the given bandwidth.
+ *
+ * \param modeList doubly-linked or circular list of modes.
+ * \param bandwidth bandwidth in MHz.
+ * \param depth color depth.
+ */
+_X_EXPORT void
+xf86ValidateModesBandwidth(ScrnInfoPtr pScrn, DisplayModePtr modeList,
+			   unsigned int bandwidth, int depth)
+{
+    DisplayModePtr mode;
+
+    for (mode = modeList; mode != NULL; mode = mode->next) {
+	if (xf86ModeBandwidth(mode, depth) > bandwidth)
+	    mode->status = MODE_BANDWIDTH;
+    }
+}
+
 /**
  * Frees any modes from the list with a status other than MODE_OK.
  *
diff --git a/hw/xfree86/modes/xf86Modes.h b/hw/xfree86/modes/xf86Modes.h
index 3722d25a0..9ad5ee653 100644
--- a/hw/xfree86/modes/xf86Modes.h
+++ b/hw/xfree86/modes/xf86Modes.h
@@ -42,6 +42,7 @@
 
 double xf86ModeHSync(DisplayModePtr mode);
 double xf86ModeVRefresh(DisplayModePtr mode);
+unsigned int xf86ModeBandwidth(DisplayModePtr mode, int depth);
 
 int
 xf86ModeWidth (DisplayModePtr mode, Rotation rotation);
@@ -78,6 +79,10 @@ void
 xf86ValidateModesSync(ScrnInfoPtr pScrn, DisplayModePtr modeList,
 		      MonPtr mon);
 
+void
+xf86ValidateModesBandwidth(ScrnInfoPtr pScrn, DisplayModePtr modeList,
+			   unsigned int bandwidth, int depth);
+
 void
 xf86PruneInvalidModes(ScrnInfoPtr pScrn, DisplayModePtr *modeList,
 		      Bool verbose);