Add support for more advanced color correction

ui/ozone/platform/drm/gpu/drm_device.cc

Index: ui/ozone/platform/drm/gpu/drm_device.cc
diff --git a/ui/ozone/platform/drm/gpu/drm_device.cc b/ui/ozone/platform/drm/gpu/drm_device.cc
index 3a30fd23e5ac3cf4b83919525a8c01dcd60e39ed..7e5f4c1d8ef6467ae73a84e5d1fc5ffc77f441ca 100644
--- a/ui/ozone/platform/drm/gpu/drm_device.cc
+++ b/ui/ozone/platform/drm/gpu/drm_device.cc
@@ -14,6 +14,7 @@
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
+#include "base/posix/safe_strerror.h"
 #include "base/task_runner.h"
 #include "base/thread_task_runner_handle.h"
 #include "base/trace_event/trace_event.h"
@@ -113,6 +114,109 @@ bool CanQueryForResources(int fd) {
   return !drmIoctl(fd, DRM_IOCTL_MODE_GETRESOURCES, &resources);
 }
 
+// TODO(robert.bradford): Replace with libdrm structures after libdrm roll.
+// https://crbug.com/586475
+struct DrmColorLut {
+  uint16_t red;
+  uint16_t green;
+  uint16_t blue;
+  uint16_t reserved;
+};
+
+struct DrmColorCtm {
+  int64_t ctm_coeff[9];
+};
+
+std::vector<uint8_t> CreateLutBlob(
+    const std::vector<GammaRampRGBEntry>& source) {
+  TRACE_EVENT0("drm", "CreateLutBlob");
+  std::vector<uint8_t> data;
+
+  data.resize(source.size() * sizeof(DrmColorLut));
+
+  DrmColorLut* lut = reinterpret_cast<DrmColorLut*>(data.data());

[spang, 2016/02/22 18:57:50]

Please use a vector<DrmColorLut> and cast to unsigned char, not the other way
around. Casting unsigned char* to DrmColorLut* is against the type aliasing
rules and undefined behavior.

[robert.bradford, 2016/02/23 19:23:01]

Ack. Replaced with a scoped_ptr w/ base::FreeDeleter and malloc based
allocations. I think this makes the memory management much clearer.

+
+  for (size_t i = 0; i < source.size(); ++i) {
+    lut[i].red = source[i].r;
+    lut[i].green = source[i].g;
+    lut[i].blue = source[i].b;
+  }
+  return data;
+}
+
+std::vector<uint8_t> CreateCTMBlob(
+    const std::vector<float>& correction_matrix) {
+  std::vector<uint8_t> data;
+  data.resize(sizeof(DrmColorCtm));
+  DrmColorCtm* ctm = reinterpret_cast<DrmColorCtm*>(data.data());

[spang, 2016/02/22 18:57:50]

Same here, it's not OK to cast unsigned char* to a struct in general. Casting a
struct to char* is allowed.

[robert.bradford, 2016/02/23 19:23:01]

Done. The cast is migrated now only to the SetBlobProperty() call point

+
+  for (int i = 0; i < 9; ++i) {
+    if (correction_matrix[i] < 0) {
+      ctm->ctm_coeff[i] = static_cast<uint64_t>(
+          -correction_matrix[i] * (static_cast<uint64_t>(1) << 32));
+      ctm->ctm_coeff[i] |= static_cast<uint64_t>(1) << 63;
+    } else {
+      ctm->ctm_coeff[i] = static_cast<uint64_t>(
+          correction_matrix[i] * (static_cast<uint64_t>(1) << 32));
+    }
+  }
+
+  return data;
+}
+
+bool SetBlobProperty(int fd,
+                     uint32_t object_id,
+                     uint32_t object_type,
+                     uint32_t prop_id,
+                     std::vector<uint8_t> data) {

[spang, 2016/02/22 18:57:50]

const &

[robert.bradford, 2016/02/23 19:23:01]

Replaced with a raw pointer now using scoped_ptr and direct memory allocations.

+  uint32_t blob_id;
+  int res;
+  res = drmModeCreatePropertyBlob(fd, data.data(), data.size(), &blob_id);
+  if (res != 0) {
+    LOG(ERROR) << "Error creating property blob: " << base::safe_strerror(res);

[spang, 2016/02/22 18:57:50]

PLOG(ERROR)

[spang, 2016/02/22 19:01:46]

Nevermind that's for strerror(errno).

+    return false;
+  }
+  res = drmModeObjectSetProperty(fd, object_id, object_type, prop_id, blob_id);
+  if (res != 0) {
+    LOG(ERROR) << "Error updating property: " << base::safe_strerror(res);

[spang, 2016/02/22 18:57:50]

PLOG(ERROR)

+    drmModeDestroyPropertyBlob(fd, blob_id);
+    return false;
+  }
+  drmModeDestroyPropertyBlob(fd, blob_id);

[spang, 2016/02/22 18:57:50]

I don't understand the lifetime of the blob. Who's responsible for destroying
the blob after this function returns? Are we just leaking it every time?

[robert.bradford, 2016/02/23 19:23:01]

I was using the stack allocation of the std::vector<unsigned char>, in the
calling stack frame, as the memory management so that the contents of what goes
into the blob isn't leaked. However as you pointed out that wasn't safe so I
went with scoped_ptr instead.

The DRM blobs themselves aren't leaked as we call drmModeDestroyPropertyBlob
(which is really a ref count, the kernel still holds onto the blob internally
whilst it's using it.)

+  return true;
+}
+
+std::vector<GammaRampRGBEntry> ResampleLut(
+    const std::vector<GammaRampRGBEntry>& lut_in,
+    size_t desired_size) {
+  TRACE_EVENT1("drm", "ResampleLut", "desired_size", desired_size);
+  if (lut_in.size() == desired_size)
+    return lut_in;
+
+  std::vector<GammaRampRGBEntry> result;
+  result.resize(desired_size);
+
+  for (size_t i = 0; i < desired_size; ++i) {
+    size_t base_index = lut_in.size() * i / desired_size;
+    size_t remaining = lut_in.size() * i % desired_size;
+    if (base_index < lut_in.size() - 1) {
+      result[i].r = lut_in[base_index].r +
+                    (lut_in[base_index + 1].r - lut_in[base_index].r) *
+                        remaining / desired_size;
+      result[i].g = lut_in[base_index].g +
+                    (lut_in[base_index + 1].g - lut_in[base_index].g) *
+                        remaining / desired_size;
+      result[i].b = lut_in[base_index].b +
+                    (lut_in[base_index + 1].b - lut_in[base_index].b) *
+                        remaining / desired_size;
+    } else {
+      result[i] = lut_in[lut_in.size() - 1];
+    }
+  }
+
+  return result;
+}
+
 }  // namespace
 
 class DrmDevice::PageFlipManager {
@@ -542,4 +646,74 @@ bool DrmDevice::SetGammaRamp(uint32_t crtc_id,
                               &g[0], &b[0]) == 0);
 }
 
+bool DrmDevice::SetColorCorrection(
+    uint32_t crtc_id,
+    const std::vector<GammaRampRGBEntry>& degamma_lut,
+    const std::vector<GammaRampRGBEntry>& gamma_lut,
+    const std::vector<float>& correction_matrix) {
+  ScopedDrmObjectPropertyPtr crtc_props(drmModeObjectGetProperties(
+      file_.GetPlatformFile(), crtc_id, DRM_MODE_OBJECT_CRTC));
+  uint64_t degamma_lut_size = 0;
+  uint64_t gamma_lut_size = 0;
+
+  for (uint32_t i = 0; i < crtc_props->count_props; ++i) {
+    ScopedDrmPropertyPtr property(
+        drmModeGetProperty(file_.GetPlatformFile(), crtc_props->props[i]));
+    if (property && !strcmp(property->name, "DEGAMMA_LUT_SIZE")) {
+      degamma_lut_size = crtc_props->prop_values[i];
+    }
+    if (property && !strcmp(property->name, "GAMMA_LUT_SIZE")) {
+      gamma_lut_size = crtc_props->prop_values[i];
+    }
+
+    if (degamma_lut_size && gamma_lut_size)
+      break;
+  }
+
+  if (degamma_lut_size == 0 || gamma_lut_size == 0) {
+    LOG(WARNING) << "No available (de)gamma tables.";

[spang, 2016/02/22 18:57:50]

Will we hit this if color correction isn't supported or does it not get called
in that case?

[robert.bradford, 2016/02/23 19:23:01]

This is protection against a broken kernel implementation. The properties are
generic DRM APIs. If you don't have a degamma table then there is no way to
correctly apply a matrix transformation (they only make sense in a linear colour
space.) Similarly if you don't have a gamma then you can't display anything
useful to the user as linear output looks strange.

+    return false;
+  }
+
+  std::vector<uint8_t> degamma_blob_data =
+      CreateLutBlob(ResampleLut(degamma_lut, degamma_lut_size));
+  std::vector<uint8_t> gamma_blob_data =
+      CreateLutBlob(ResampleLut(gamma_lut, gamma_lut_size));
+  std::vector<uint8_t> ctm_blob_data = CreateCTMBlob(correction_matrix);
+
+  for (uint32_t i = 0; i < crtc_props->count_props; ++i) {
+    ScopedDrmPropertyPtr property(
+        drmModeGetProperty(file_.GetPlatformFile(), crtc_props->props[i]));
+    if (!property)
+      continue;
+
+    if (!strcmp(property->name, "DEGAMMA_LUT")) {
+      if (!SetBlobProperty(file_.GetPlatformFile(), crtc_id,
+                           DRM_MODE_OBJECT_CRTC, crtc_props->props[i],
+                           degamma_blob_data)) {
+        LOG(WARNING) << "Error setting degamma property.";

[spang, 2016/02/22 18:57:50]

Can you pass the property name into SetBlobProperty, add it to the internal
LOG(ERROR), and then remove these duplicate logs?

[robert.bradford, 2016/02/23 19:23:01]

Done.

+        return false;
+      }
+    }
+    if (!strcmp(property->name, "GAMMA_LUT")) {
+      if (!SetBlobProperty(file_.GetPlatformFile(), crtc_id,
+                           DRM_MODE_OBJECT_CRTC, crtc_props->props[i],
+                           gamma_blob_data)) {
+        LOG(WARNING) << "Error setting gamma property.";
+        return false;
+      }
+    }
+    if (!strcmp(property->name, "CTM_MATRIX")) {
+      if (!SetBlobProperty(file_.GetPlatformFile(), crtc_id,
+                           DRM_MODE_OBJECT_CRTC, crtc_props->props[i],
+                           ctm_blob_data)) {
+        LOG(WARNING) << "Error setting correction matrix property.";
+        return false;
+      }
+    }
+  }
+
+  return true;
+}
+
 }  // namespace ui