[libcamera-devel] [PATCH 1/3] libcamera: v4l2_subdevice: Implement ENUM_FRAME_SIZES

[Jacopo Mondi]

Implement enumFormat() methods to enumerate the available image
resolutions on the subdevice.

Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
 src/libcamera/include/v4l2_subdevice.h | 11 ++++
 src/libcamera/v4l2_subdevice.cpp       | 90 ++++++++++++++++++++++++++
 2 files changed, 101 insertions(+)

diff --git a/src/libcamera/include/v4l2_subdevice.h b/src/libcamera/include/v4l2_subdevice.h
index 82fa6685ab52..c7045776555c 100644
--- a/src/libcamera/include/v4l2_subdevice.h
+++ b/src/libcamera/include/v4l2_subdevice.h
@@ -14,6 +14,16 @@ namespace libcamera {
 class MediaEntity;
 struct Rectangle;
 
+struct V4L2SubdeviceFormatEnum {
+	unsigned int index;
+	uint32_t mbus_code;
+
+	uint32_t minWidth;
+	uint32_t maxWidth;
+	uint32_t minHeight;
+	uint32_t maxHeight;
+};
+
 struct V4L2SubdeviceFormat {
 	uint32_t mbus_code;
 	uint32_t width;
@@ -36,6 +46,7 @@ public:
 	int setCrop(unsigned int pad, Rectangle *rect);
 	int setCompose(unsigned int pad, Rectangle *rect);
 
+	int enumFormat(unsigned int pad, V4L2SubdeviceFormatEnum *formatEnum);
 	int getFormat(unsigned int pad, V4L2SubdeviceFormat *format);
 	int setFormat(unsigned int pad, V4L2SubdeviceFormat *format);
 
diff --git a/src/libcamera/v4l2_subdevice.cpp b/src/libcamera/v4l2_subdevice.cpp
index b436f73cc75f..5665154a2762 100644
--- a/src/libcamera/v4l2_subdevice.cpp
+++ b/src/libcamera/v4l2_subdevice.cpp
@@ -26,6 +26,52 @@ namespace libcamera {
 
 LOG_DEFINE_CATEGORY(V4L2Subdev)
 
+/**
+ * \struct V4L2SubdeviceFormatEnum
+ * \brief The V4L2 sub-device image size enumeration
+ *
+ * This structure describes an image resolution as enumerated by the V4L2
+ * sub-device. The structure is used as format exchange between the caller and
+ * the enumFormat() method. The caller is responsible to fill the media bus
+ * code to use and the index of the format to be enumerated.
+ */
+
+/**
+ * \var V4L2SubdeviceFormatEnum::index
+ * \brief The index of the format to be enumerated
+ */
+
+/**
+ * \var V4L2SubdeviceFormatEnum::mbus_code
+ * \brief The pixel format identification code for the formats to enumerate
+ *
+ * \sa V4L2SubdeviceFormat for media bus format pixel code description.
+ */
+
+/**
+ * \var V4L2SubdeviceFormatEnum::minWidth
+ * \brief The minimum width of the enumerated format as reported by the V4L2
+ * sub-device
+ */
+
+/**
+ * \var V4L2SubdeviceFormatEnum::maxWidth
+ * \brief The maximum width of the enumerated format as reported by the V4L2
+ * sub-device
+ */
+
+/**
+ * \var V4L2SubdeviceFormatEnum::minHeight
+ * \brief The minimum height of the enumerated format as reported by the V4L2
+ * sub-device
+ */
+
+/**
+ * \var V4L2SubdeviceFormatEnum::maxHeight
+ * \brief The maximum height of the enumerated format as reported by the V4L2
+ * sub-device
+ */
+
 /**
  * \struct V4L2SubdeviceFormat
  * \brief The V4L2 sub-device image format and sizes
@@ -171,6 +217,50 @@ int V4L2Subdevice::setCompose(unsigned int pad, Rectangle *rect)
 	return setSelection(pad, V4L2_SEL_TGT_COMPOSE, rect);
 }
 
+/**
+ * \brief Enumerate the sub-device image resolutions
+ * \param[in] pad The 0-indexed pad number to enumerate formats on
+ * \param[inout] formatEnum The format enumeration description
+ *
+ * The method retrieve the image resolution of the image format with index
+ * formatEnum.index for the pixel format specified by formatEnum.mbus_code.
+ *
+ * To enumerate image resolutions, the caller shall start enumerating all
+ * formats by setting the formatEnum.index field to 0, and increasing it by
+ * one for any successive call, until the -EINVAL return code is returned.
+ *
+ * \return 0 on success, or a negative error code otherwise
+ */
+int V4L2Subdevice::enumFormat(unsigned int pad,
+			      V4L2SubdeviceFormatEnum *formatEnum)
+{
+	struct v4l2_subdev_frame_size_enum sizeEnum = {};
+
+	sizeEnum.index = formatEnum->index;
+	sizeEnum.code = formatEnum->mbus_code;
+	sizeEnum.pad = pad;
+	sizeEnum.which = V4L2_SUBDEV_FORMAT_ACTIVE;
+
+	int ret = ioctl(fd_, VIDIOC_SUBDEV_ENUM_FRAME_SIZE, &sizeEnum);
+	if (ret) {
+		ret = -errno;
+		if (ret == -EINVAL)
+			return ret;
+
+		LOG(V4L2Subdev, Error)
+			<< "Unable to enumerate format on pad " << pad
+			<< " of " << deviceNode_ << ": " << strerror(-ret);
+		return ret;
+	}
+
+	formatEnum->maxWidth = sizeEnum.max_width;
+	formatEnum->minWidth = sizeEnum.min_width;
+	formatEnum->maxHeight = sizeEnum.max_height;
+	formatEnum->minHeight = sizeEnum.min_height;
+
+	return 0;
+}
+
 /**
  * \brief Retrieve the image format set on one of the V4L2 subdevice pads
  * \param[in] pad The 0-indexed pad number the format is to be retrieved from
-- 
2.20.1