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| author | Jacopo Mondi <jacopo+renesas@jmondi.org> | 2020-07-17 17:53:20 +0300 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab+huawei@kernel.org> | 2020-08-18 16:47:20 +0300 |
| commit | ddf5c927bd362b8b7c5e09e2e2271e4348e76b76 (patch) | |
| tree | 02a44583ee43ad036f5567052d7763db760dd31f /include | |
| parent | d9857a6d81d327f39ef7a1ead50ebab458dd5564 (diff) | |
| download | linux-ddf5c927bd362b8b7c5e09e2e2271e4348e76b76.tar.xz | |
media: v4l2- mediabus: Add usage note for V4L2_MBUS_*
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>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/media/v4l2-mediabus.h | 33 |
1 files changed, 29 insertions, 4 deletions
diff --git a/include/media/v4l2-mediabus.h b/include/media/v4l2-mediabus.h index 45f88f0248c4..59b1de197114 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) |