Support failing modeset

chromeos/display/output_configurator.cc

Index: chromeos/display/output_configurator.cc
diff --git a/chromeos/display/output_configurator.cc b/chromeos/display/output_configurator.cc
index 67da273b64965469c0b9d252e2e64e3c8ab16158..3e2c836ffbdd2dc3891380983a54500dcda4db1e 100644
--- a/chromeos/display/output_configurator.cc
+++ b/chromeos/display/output_configurator.cc
@@ -943,7 +943,7 @@ bool OutputConfigurator::EnterState(
   DCHECK_EQ(cached_outputs_.size(), updated_outputs.size());
   if (!updated_outputs.empty()) {
     delegate_->CreateFrameBuffer(width, height, updated_outputs);
-    for (size_t i = 0; i < updated_outputs.size(); ++i) {
+    for (size_t i = 0; i < updated_outputs.size(); ) {

[Daniel Erat, 2013/12/21 14:25:54]

please structure this code in a more logical way:

for (size_t i = 0; i < updated_outputs.size(); ++i) {
  ...
  while (!delegate_->ConfigureCrtc(...)) {
    updated_outputs[i].current_mode = ...
    // break when you run out of modes to try
  }
}

       const OutputSnapshot& output = updated_outputs[i];
       if (delegate_->ConfigureCrtc(output.crtc, output.current_mode,
                                    output.output, output.x, output.y)) {
@@ -956,7 +956,24 @@ bool OutputConfigurator::EnterState(
                      << " output=" << output.output
                      << " x=" << output.x
                      << " y=" << output.y;
+
+        int best_mode_pixels = 0;
+        const ModeInfo mode_info =
+               output.mode_infos.find(output.current_mode)->second;

[Daniel Erat, 2013/12/21 14:25:54]

indent 4 spaces, not 7

+        int pixels = mode_info.width * mode_info.height;

[Daniel Erat, 2013/12/21 14:25:54]

give this a better name like current_mode_pixels

+        for (ModeInfoMap::const_iterator it = output.mode_infos.begin();
+             it != output.mode_infos.end(); it++) {
+          int pixel_count = it->second.width * it->second.height;
+          if ((pixel_count < pixels) && (pixel_count > best_mode_pixels)) {
+            updated_outputs[i].current_mode = it->first;
+            best_mode_pixels = pixel_count;
+          }
+        }

[marcheu, 2013/12/21 01:56:15]

If we are in mirror mode, and modeset fails on one of the monitors, we will end
up with two mismatched modes. I'm not sure what the effect will be, but most
likely not what we want. We should probably fix that before landing this change.

To fix it, it might be sufficient to return false in this case.

+
+        if (best_mode_pixels != 0)
+        continue;

[Daniel Erat, 2013/12/21 14:25:54]

indent 2 spaces, not 0

       }
+      i++;
     }
   }