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media: subdev: Split v4l2_subdev_get_frame_desc_passthrough() into locked and unlocked

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JIRA: https://redhat.atlassian.net/browse/RHEL-162130

commit 64d712aa31f30a125291e7c47209ef7ebd3285a3
Author: Tomi Valkeinen <tomi.valkeinen+renesas@ideasonboard.com>
Date: Tue, 17 Mar 2026 14:09:42 +0200

  The recently added v4l2_subdev_get_frame_desc_passthrough() can be used
  directly as an implementation for .get_frame_desc subdev op. However, in
  some cases the drivers may want to add some customizations, while the
  bulk of the work is still identical to what
  v4l2_subdev_get_frame_desc_passthrough() does. Current locking scheme
  makes this impossible to do properly.

  Split v4l2_subdev_get_frame_desc_passthrough() into two functions:

  __v4l2_subdev_get_frame_desc_passthrough(), which takes a locked subdev
  state as a parameter, instead of locking and getting the active state
  internally. Other than that, it does the same as
  v4l2_subdev_get_frame_desc_passthrough() used to do.

  v4l2_subdev_get_frame_desc_passthrough(), which locks the active state
  and calls __v4l2_subdev_get_frame_desc_passthrough().

  In other words, v4l2_subdev_get_frame_desc_passthrough() works as
  before, but drivers can now alternatively add custom .get_frame_desc
  code and call v4l2_subdev_get_frame_desc_passthrough().

  An example use case is with DS90UB953 serializer: in normal use the
  serializer passes through everything, but when test-pattern-generator
  (TPG) is used, an internal TPG source is used. After this commit, the
  UB953 get_frame_desc() can lock the state, look at the routing table to
  see if we're in normal or TPG mode, then either call
  __v4l2_subdev_get_frame_desc_passthrough() if in normal mode, or
  construct a TPG frame desc if in TPG mode.

  Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas@ideasonboard.com>
  [Sakari Ailus: Rebase on an earlier remote source pad error code fix.]
  Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
  Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
  Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>

Signed-off-by: Kate Hsuan <hpa@redhat.com>
This commit is contained in:
Kate Hsuan
2026-05-15 15:46:54 +08:00
parent 12436b0d0e
commit 66a0dc3221
2 changed files with 61 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/media/v4l2-core/v4l2-subdev.c
+28 -20
View File
@@ -2441,21 +2441,21 @@ int v4l2_subdev_s_stream_helper(struct v4l2_subdev *sd, int enable)
}
EXPORT_SYMBOL_GPL(v4l2_subdev_s_stream_helper);
int v4l2_subdev_get_frame_desc_passthrough(struct v4l2_subdev *sd,
unsigned int pad,
struct v4l2_mbus_frame_desc *fd)
int __v4l2_subdev_get_frame_desc_passthrough(struct v4l2_subdev *sd,
struct v4l2_subdev_state *state,
unsigned int pad,
struct v4l2_mbus_frame_desc *fd)
{
struct media_pad *local_sink_pad;
struct v4l2_subdev_route *route;
struct v4l2_subdev_state *state;
struct device *dev = sd->dev;
int ret = 0;
lockdep_assert_held(state->lock);
if (WARN_ON(!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE)))
return -EINVAL;
state = v4l2_subdev_lock_and_get_active_state(sd);
/* Iterate over sink pads */
media_entity_for_each_pad(&sd->entity, local_sink_pad) {
struct v4l2_mbus_frame_desc source_fd;
@@ -2482,15 +2482,12 @@ int v4l2_subdev_get_frame_desc_passthrough(struct v4l2_subdev *sd,
if (IS_ERR(remote_source_pad)) {
dev_dbg(dev, "Failed to find remote pad for sink pad %u\n",
local_sink_pad->index);
ret = PTR_ERR(remote_source_pad);
goto out_unlock;
return PTR_ERR(remote_source_pad);
}
remote_sd = media_entity_to_v4l2_subdev(remote_source_pad->entity);
if (!remote_sd) {
ret = -EINVAL;
goto out_unlock;
}
if (!remote_sd)
return -EINVAL;
ret = v4l2_subdev_call(remote_sd, pad,
get_frame_desc,
@@ -2500,7 +2497,7 @@ int v4l2_subdev_get_frame_desc_passthrough(struct v4l2_subdev *sd,
dev_err(dev,
"Failed to get frame desc from remote subdev %s\n",
remote_sd->name);
goto out_unlock;
return ret;
}
have_source_fd = true;
@@ -2511,8 +2508,7 @@ int v4l2_subdev_get_frame_desc_passthrough(struct v4l2_subdev *sd,
dev_err(dev,
"Frame desc type mismatch: %u != %u\n",
fd->type, source_fd.type);
ret = -EPIPE;
goto out_unlock;
return -EPIPE;
}
}
@@ -2527,14 +2523,12 @@ int v4l2_subdev_get_frame_desc_passthrough(struct v4l2_subdev *sd,
dev_dbg(dev,
"Failed to find stream %u from source frame desc\n",
route->sink_stream);
ret = -EPIPE;
goto out_unlock;
return -EPIPE;
}
if (fd->num_entries >= V4L2_FRAME_DESC_ENTRY_MAX) {
dev_dbg(dev, "Frame desc entry limit reached\n");
ret = -ENOSPC;
goto out_unlock;
return -ENOSPC;
}
fd->entry[fd->num_entries] = *source_entry;
@@ -2545,7 +2539,21 @@ int v4l2_subdev_get_frame_desc_passthrough(struct v4l2_subdev *sd,
}
}
out_unlock:
return 0;
}
EXPORT_SYMBOL_GPL(__v4l2_subdev_get_frame_desc_passthrough);
int v4l2_subdev_get_frame_desc_passthrough(struct v4l2_subdev *sd,
unsigned int pad,
struct v4l2_mbus_frame_desc *fd)
{
struct v4l2_subdev_state *state;
int ret;
state = v4l2_subdev_lock_and_get_active_state(sd);
ret = __v4l2_subdev_get_frame_desc_passthrough(sd, state, pad, fd);
v4l2_subdev_unlock_state(state);
return ret;
include/media/v4l2-subdev.h
+33 -5
View File
@@ -1699,15 +1699,15 @@ int v4l2_subdev_disable_streams(struct v4l2_subdev *sd, u32 pad,
int v4l2_subdev_s_stream_helper(struct v4l2_subdev *sd, int enable);
/**
* v4l2_subdev_get_frame_desc_passthrough() - Helper to implement the subdev
* get_frame_desc operation in simple passthrough cases
* __v4l2_subdev_get_frame_desc_passthrough - Helper to implement the
* subdev get_frame_desc operation in simple passthrough cases
* @sd: The subdevice
* @state: The locked subdevice active state
* @pad: The source pad index
* @fd: The mbus frame desc
*
* This helper implements get_frame_desc operation for subdevices that pass
* streams through without modification. It can be assigned directly as the
* .get_frame_desc callback in &v4l2_subdev_pad_ops.
* This helper implements the get_frame_desc operation for subdevices that pass
* streams through without modification.
*
* The helper iterates over the subdevice's sink pads, calls get_frame_desc on
* the remote subdevice connected to each sink pad, and collects the frame desc
@@ -1720,6 +1720,34 @@ int v4l2_subdev_s_stream_helper(struct v4l2_subdev *sd, int enable);
* sink pads are involved and the upstream sources report different frame desc
* types, -EPIPE is returned.
*
* The caller must hold the subdevice's active state lock. This variant is
* intended for drivers that need to perform additional work around the
* passthrough frame descriptor collection. Drivers that do not need any
* customization should use v4l2_subdev_get_frame_desc_passthrough() instead.
*
* Return: 0 on success, or a negative error code otherwise.
*/
int __v4l2_subdev_get_frame_desc_passthrough(struct v4l2_subdev *sd,
struct v4l2_subdev_state *state,
unsigned int pad,
struct v4l2_mbus_frame_desc *fd);
/**
* v4l2_subdev_get_frame_desc_passthrough() - Helper to implement the subdev
* get_frame_desc operation in simple passthrough cases
* @sd: The subdevice
* @pad: The source pad index
* @fd: The mbus frame desc
*
* This function locks the subdevice's active state, calls
* __v4l2_subdev_get_frame_desc_passthrough(), and unlocks the state.
*
* This function can be assigned directly as the .get_frame_desc callback in
* &v4l2_subdev_pad_ops for subdevices that pass streams through without
* modification. Drivers that need to perform additional work should use
* __v4l2_subdev_get_frame_desc_passthrough() in their custom
* .get_frame_desc implementation instead.
*
* Return: 0 on success, or a negative error code otherwise.
*/
int v4l2_subdev_get_frame_desc_passthrough(struct v4l2_subdev *sd,