media/gpu/v4l2: Correct v4l2_format from Tegra driver.

Originally, we use the value of num_planes returned from driver.
However, the Tegra driver returns the wrong value for YM12 pixel
format. This CL change to use the correct value.

BUG=938156
TEST=run video_encode_accelerator_unittests on nyan_blaze
TEST=run video_decode_accelerator_tests on nyan_blaze

Change-Id: I6fc19e8a9f4a20a5b8c92628ea485c633fd7d8cf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1765093
Commit-Queue: Chih-Yu Huang <akahuang@chromium.org>
Reviewed-by: Alexandre Courbot <acourbot@chromium.org>
Reviewed-by: Hirokazu Honda <hiroh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#691497}

media/gpu/v4l2/tegra_v4l2_device.cc

@@ -64,15 +64,26 @@ int TegraV4L2Device::Ioctl(int flags, void* arg) {
     return ret;
 
   // Workarounds for Tegra's broken closed-source V4L2 interface.
-  struct v4l2_format* format;
   switch (flags) {
-    // VIDIOC_G_FMT returns 0 planes for multiplanar formats with 1 plane.
-    case static_cast<int>(VIDIOC_G_FMT):
-      format = static_cast<struct v4l2_format*>(arg);
-      if (V4L2_TYPE_IS_MULTIPLANAR(format->type) &&
-          format->fmt.pix_mp.num_planes == 0)
-        format->fmt.pix_mp.num_planes = 1;
+    case static_cast<int>(VIDIOC_S_FMT): {
+      struct v4l2_format format;
+      memcpy(&format, arg, sizeof(struct v4l2_format));
+      v4l2_format_cache_[static_cast<enum v4l2_buf_type>(format.type)] = format;
       break;
+    }
+    case static_cast<int>(VIDIOC_G_FMT): {
+      // The driver doesn't fill values of returned v4l2_format correctly. Set
+      // the value that is previously passed to driver via VIDIOC_S_FMT.
+      struct v4l2_format* format = static_cast<struct v4l2_format*>(arg);
+      const auto it = v4l2_format_cache_.find(
+          static_cast<enum v4l2_buf_type>(format->type));
+      if (it != v4l2_format_cache_.end()) {
+        format->fmt.pix_mp.pixelformat = it->second.fmt.pix_mp.pixelformat;
+        if (format->fmt.pix_mp.num_planes == 0)
+          format->fmt.pix_mp.num_planes = it->second.fmt.pix_mp.num_planes;
+      }
+      break;
+    }
     default:
       break;
   }

media/gpu/v4l2/tegra_v4l2_device.h

@@ -11,6 +11,7 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#include <map>
 #include <vector>
 
 #include "base/macros.h"
@@ -86,6 +87,10 @@ class TegraV4L2Device : public V4L2Device {
   // The actual device fd.
   int device_fd_ = -1;
 
+  // The v4l2_format cache passed to the driver via VIDIOC_S_FMT. The key is
+  // v4l2_buf_type.
+  std::map<enum v4l2_buf_type, struct v4l2_format> v4l2_format_cache_;
+
   DISALLOW_COPY_AND_ASSIGN(TegraV4L2Device);
 };