@@ -11,9 +11,34 @@
#include <linux/v4l2-mediabus.h>
#include <linux/bitops.h>
+/*
+ * How to use the V4L2_MBUS_* flags:
+ * Flags are defined for each of the possible states and values of a media
+ * bus configuration parameter. One and only one bit of each group of flags
+ * shall be set by the users of the v4l2_subdev_pad_ops.get_mbus_config and
+ * v4l2_subdev_pad_ops.set_mbus_config operations to ensure that no
+ * conflicting settings are specified when reporting and setting the media bus
+ * configuration with the two operations respectively. For example, it is
+ * invalid to set or clear both the V4L2_MBUS_HSYNC_ACTIVE_HIGH and the
+ * V4L2_MBUS_HSYNC_ACTIVE_LOW flag at the same time. Instead either flag
+ * V4L2_MBUS_HSYNC_ACTIVE_HIGH or flag V4L2_MBUS_HSYNC_ACTIVE_LOW shall be
+ * set. The same is true for the V4L2_MBUS_CSI2_1/2/3/4_LANE flags group: only
+ * one of these four bits shall be set.
+ *
+ * TODO: replace the existing V4L2_MBUS_* flags with structures of fields
+ * to avoid conflicting settings.
+ *
+ * In example:
+ * #define V4L2_MBUS_HSYNC_ACTIVE_HIGH BIT(2)
+ * #define V4L2_MBUS_HSYNC_ACTIVE_LOW BIT(3)
+ * will be replaced by a field whose value reports the intended active state of
+ * the signal:
+ * unsigned int v4l2_mbus_hsync_active : 1;
+ */
+
/* Parallel flags */
/*
- * Can the client run in master or in slave mode. By "Master mode" an operation
+ * The client runs in master or in slave mode. By "Master mode" an operation
* mode is meant, when the client (e.g., a camera sensor) is producing
* horizontal and vertical synchronisation. In "Slave mode" the host is
* providing these signals to the slave.
@@ -45,17 +70,17 @@
#define V4L2_MBUS_DATA_ENABLE_LOW BIT(15)
/* Serial flags */
-/* How many lanes the client can use */
+/* CSI-2 D-PHY number of data lanes. */
#define V4L2_MBUS_CSI2_1_LANE BIT(0)
#define V4L2_MBUS_CSI2_2_LANE BIT(1)
#define V4L2_MBUS_CSI2_3_LANE BIT(2)
#define V4L2_MBUS_CSI2_4_LANE BIT(3)
-/* On which channels it can send video data */
+/* CSI-2 Virtual Channel identifiers. */
#define V4L2_MBUS_CSI2_CHANNEL_0 BIT(4)
#define V4L2_MBUS_CSI2_CHANNEL_1 BIT(5)
#define V4L2_MBUS_CSI2_CHANNEL_2 BIT(6)
#define V4L2_MBUS_CSI2_CHANNEL_3 BIT(7)
-/* Does it support only continuous or also non-continuous clock mode */
+/* Clock non-continuous mode support. */
#define V4L2_MBUS_CSI2_CONTINUOUS_CLOCK BIT(8)
#define V4L2_MBUS_CSI2_NONCONTINUOUS_CLOCK BIT(9)
With the removal of the legacy g_mbus_config and s_mbus_config video operations, the sole users of V4L2_MBUS_* flags are now the newly introduced get_mbus_config and set_mbus_config pad operations. As the semantic of the new operations differs from the semantic of the legacy ones, add a usage note in the v4l2-mediabus.h header to specify how to use the flags. Also add a TODO note to record that we intend to replace the existing flags with fields, to prevent users from mixing conflicting values in a single operation call. Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org> --- include/media/v4l2-mediabus.h | 33 +++++++++++++++++++++++++++++---- 1 file changed, 29 insertions(+), 4 deletions(-) -- 2.27.0