media: v4l: subdev: Add pre_streamon and post_streamoff callbacks

Add pre_streamon and post_streamoff callbacks that can be used to set a
CSI-2 transmitter to LP-11 or LP-111 mode. This can be used by receiver
drivers to reliably initialise the receiver when its initialisation
requires software involvement.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index 5364e3a6ac9bf423ebde5cf513182055f4c49035..95ec18c2f49ce96728a4575d06b5c2774fa680fd 100644 (file)
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -354,6 +354,16 @@ struct v4l2_mbus_frame_desc {
        unsigned short num_entries;
 };
 
+/**
+ * enum v4l2_subdev_pre_streamon_flags - Flags for pre_streamon subdev core op
+ *
+ * @V4L2_SUBDEV_PRE_STREAMON_FL_MANUAL_LP: Set the transmitter to either LP-11
+ *     or LP-111 mode before call to s_stream().
+ */
+enum v4l2_subdev_pre_streamon_flags {
+       V4L2_SUBDEV_PRE_STREAMON_FL_MANUAL_LP = BIT(0),
+};
+
 /**
  * struct v4l2_subdev_video_ops - Callbacks used when v4l device was opened
  *                               in video mode.
@@ -409,6 +419,19 @@ struct v4l2_mbus_frame_desc {
  * @s_rx_buffer: set a host allocated memory buffer for the subdev. The subdev
  *     can adjust @size to a lower value and must not write more data to the
  *     buffer starting at @data than the original value of @size.
+ *
+ * @pre_streamon: May be called before streaming is actually started, to help
+ *     initialising the bus. Current usage is to set a CSI-2 transmitter to
+ *     LP-11 or LP-111 mode before streaming. See &enum
+ *     v4l2_subdev_pre_streamon_flags.
+ *
+ *     pre_streamon shall return error if it cannot perform the operation as
+ *     indicated by the flags argument. In particular, -EACCES indicates lack
+ *     of support for the operation. The caller shall call post_streamoff for
+ *     each successful call of pre_streamon.
+ *
+ * @post_streamoff: Called after streaming is stopped, but if and only if
+ *     pre_streamon was called earlier.
  */
 struct v4l2_subdev_video_ops {
        int (*s_routing)(struct v4l2_subdev *sd, u32 input, u32 output, u32 config);
@@ -435,6 +458,8 @@ struct v4l2_subdev_video_ops {
                        struct v4l2_dv_timings *timings);
        int (*s_rx_buffer)(struct v4l2_subdev *sd, void *buf,
                           unsigned int *size);
+       int (*pre_streamon)(struct v4l2_subdev *sd, u32 flags);
+       int (*post_streamoff)(struct v4l2_subdev *sd);
 };
 
 /**