[PATCH v3 1/8] media: v4l2-subdv: Introduce get_mbus_config pad op

[Jacopo Mondi <jacopo+renesas@jmondi.org>]

Introduce a new pad operation to allow retrieving the media bus
configuration on a subdevice pad.

The newly introduced operation reassembles the s/g_mbus_config video
operation, which have been on their way to be deprecated since a long
time.

Currently only support MIPI CSI-2 mbus configuration.

Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
---
 include/media/v4l2-mediabus.h |  2 +-
 include/media/v4l2-subdev.h   | 31 +++++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/include/media/v4l2-mediabus.h b/include/media/v4l2-mediabus.h
index 45f88f0248c4..438c7337248f 100644
--- a/include/media/v4l2-mediabus.h
+++ b/include/media/v4l2-mediabus.h
@@ -22,7 +22,7 @@
 #define V4L2_MBUS_SLAVE				BIT(1)
 /*
  * Signal polarity flags
- * Note: in BT.656 mode HSYNC, FIELD, and VSYNC are unused
+ * Note: in BT.656 mode HSYNC, FIELD, DATA_ACTIVE and VSYNC are unused
  * V4L2_MBUS_[HV]SYNC* flags should be also used for specifying
  * configuration of hardware that uses [HV]REF signals
  */
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index a4848de59852..654b29f8c01e 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -670,6 +670,33 @@ struct v4l2_subdev_pad_config {
  *
  * @set_frame_desc: set the low level media bus frame parameters, @fd array
  *                  may be adjusted by the subdev driver to device capabilities.
+ *
+ * @get_mbus_config: get the current media bus configuration. This operation is
+ *		     intended to be used to synchronize the media bus
+ *		     configuration parameters between receivers and
+ *		     transmitters. The static bus configuration is usually
+ *		     received from the firmware interface, and updated
+ *		     dynamically using this operation to retrieve bus
+ *		     configuration parameters which could change at run-time.
+ *		     Callers should make sure they get the most up-to-date as
+ *		     possible configuration from the connected sub-device,
+ *		     likely calling this operation as close as possible to
+ *		     stream on time. The operation is allowed to fail if the
+ *		     the pad index it has been called on is unsupported.
+ *
+ * @set_mbus_config: set the media bus configuration. This operations is
+ *		     intended to allow, in combination with the
+ *		     get_mbus_format operation, the negotiation of media bus
+ *		     configuration parameters between media subdevices.
+ *		     The initial media bus configuration is retrieved from
+ *		     the firmware interface and later updated through this
+ *		     operation if the sub-device allows changing it.
+ *		     The operation shall not fail if the requested configuration
+ *		     is not supported, but the driver shall update the received
+ *		     %config argument to reflect what has been actually applied
+ *		     to its media bus configuration. The operation is allowed
+ *		     to fail if the pad index it has been called on is
+ *		     unsupported.
  */
 struct v4l2_subdev_pad_ops {
 	int (*init_cfg)(struct v4l2_subdev *sd,
@@ -710,6 +737,10 @@ struct v4l2_subdev_pad_ops {
 			      struct v4l2_mbus_frame_desc *fd);
 	int (*set_frame_desc)(struct v4l2_subdev *sd, unsigned int pad,
 			      struct v4l2_mbus_frame_desc *fd);
+	int (*get_mbus_config)(struct v4l2_subdev *sd, unsigned int pad,
+			       struct v4l2_mbus_config *config);
+	int (*set_mbus_config)(struct v4l2_subdev *sd, unsigned int pad,
+			       struct v4l2_mbus_config *config);
 };
 
 /**
-- 
2.26.2