media/gpu/v4l2: Pass UBWC modifier to V4L2

V4L2 does not support modifiers with the current API.
This is a way to allow UBWC to be turned on for
Qualcomm SOCs by using a special format.

This should be reverted once V4L2 has an api that
supports modifiers.

BUG=b:149525848
BUG=b:166275274
TEST=none

Change-Id: I89e8d543fc8f021fd184bbfe26fdab689747c330
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2343804
Commit-Queue: Fritz Koenig <frkoenig@chromium.org>
Reviewed-by: Alexandre Courbot <acourbot@chromium.org>
Cr-Commit-Position: refs/heads/master@{#803912}

media/gpu/v4l2/v4l2_device.cc

@@ -1274,6 +1274,19 @@ bool V4L2Queue::SupportsRequests() {
   return supports_requests_;
 }
 
+base::Optional<struct v4l2_format> V4L2Queue::SetModifierFormat(
+    uint64_t modifier,
+    const gfx::Size& size) {
+  if (DRM_FORMAT_MOD_QCOM_COMPRESSED == modifier) {
+    const uint32_t v4l2_pix_fmt_nv12_ubwc = v4l2_fourcc('Q', '1', '2', '8');
+    auto format = SetFormat(v4l2_pix_fmt_nv12_ubwc, size, 0);
+    if (!format)
+      VPLOGF(1) << "Failed to set magic modifier format.";
+    return format;
+  }
+  return base::nullopt;
+}
+
 // This class is used to expose V4L2Queue's constructor to this module. This is
 // to ensure that nobody else can create instances of it.
 class V4L2QueueFactory {

media/gpu/v4l2/v4l2_device.h

@@ -397,6 +397,11 @@ class MEDIA_GPU_EXPORT V4L2Queue
   // Returns true if requests are supported by this queue.
   bool SupportsRequests();
 
+  // TODO (b/166275274) : Remove this once V4L2 properly supports modifiers.
+  // Out of band method to configure V4L2 for modifier use.
+  base::Optional<struct v4l2_format> SetModifierFormat(uint64_t modifier,
+                                                       const gfx::Size& size);
+
  private:
   ~V4L2Queue();
 

media/gpu/v4l2/v4l2_video_decoder.cc

@@ -344,6 +344,24 @@ bool V4L2VideoDecoder::SetupOutputFormat(const gfx::Size& size,
                << " != " << layout->size().ToString();
       return false;
     }
+
+    if (layout->modifier() &&
+        layout->modifier() != gfx::NativePixmapHandle::kNoModifier) {
+      base::Optional<struct v4l2_format> modifier_format =
+          output_queue_->SetModifierFormat(layout->modifier(), size);
+      if (!modifier_format)
+        return false;
+
+      gfx::Size size_for_modifier_format(format->fmt.pix_mp.width,
+                                         format->fmt.pix_mp.height);
+      if (size_for_modifier_format != adjusted_size) {
+        VLOGF(1)
+            << "Buffers were allocated for " << adjusted_size.ToString()
+            << " but modifier format is expecting buffers to be allocated for "
+            << size_for_modifier_format.ToString();
+        return false;
+      }
+    }
   }
 
   return true;