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@xxxxxxxxxx> --- include/media/v4l2-mediabus.h | 33 +++++++++++++++++++++++++++++---- 1 file changed, 29 insertions(+), 4 deletions(-) diff --git a/include/media/v4l2-mediabus.h b/include/media/v4l2-mediabus.h index 45f88f0248c4..14818901e713 100644 --- a/include/media/v4l2-mediabus.h +++ b/include/media/v4l2-mediabus.h @@ -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) -- 2.27.0
