Commit ddf5c927 authored by Jacopo Mondi's avatar Jacopo Mondi Committed by Mauro Carvalho Chehab
Browse files

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: default avatarJacopo Mondi <jacopo+renesas@jmondi.org>
Signed-off-by: default avatarHans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+huawei@kernel.org>
parent d9857a6d

include/media/v4l2-mediabus.h

+29 −4
Original line number Diff line number Diff line
@@ -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)

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