media: v4l: subdev: Add len_routes field to struct v4l2_subdev_routing

The len_routes field is used to tell the size of the routes array in
struct v4l2_subdev_routing. This way the number of routes returned from
S_ROUTING IOCTL may be larger than the number of routes provided, in case
there are more routes returned by the driver.

Note that this uAPI is still disabled in the code, so this change can
safely be done. Anyone who manually patched the code to enable this uAPI
must update their code.

The patch also increases the number of reserved fields in struct
v4l2_subdev_routing.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
This commit is contained in:
Sakari Ailus 2023-08-31 14:56:28 +03:00 committed by Hans Verkuil
parent 38c84932de
commit 83a22a07cd
5 changed files with 48 additions and 24 deletions

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@ -43,23 +43,38 @@ The routing configuration determines the flows of data inside an entity.
Drivers report their current routing tables using the
``VIDIOC_SUBDEV_G_ROUTING`` ioctl and application may enable or disable routes
with the ``VIDIOC_SUBDEV_S_ROUTING`` ioctl, by adding or removing routes and
setting or clearing flags of the ``flags`` field of a
struct :c:type:`v4l2_subdev_route`.
setting or clearing flags of the ``flags`` field of a struct
:c:type:`v4l2_subdev_route`.
All stream configurations are reset when ``VIDIOC_SUBDEV_S_ROUTING`` is called. This
means that the userspace must reconfigure all streams after calling the ioctl
with e.g. ``VIDIOC_SUBDEV_S_FMT``.
All stream configurations are reset when ``VIDIOC_SUBDEV_S_ROUTING`` is called.
This means that the userspace must reconfigure all stream formats and selections
after calling the ioctl with e.g. ``VIDIOC_SUBDEV_S_FMT``.
Only subdevices which have both sink and source pads can support routing.
When inspecting routes through ``VIDIOC_SUBDEV_G_ROUTING`` and the application
provided ``num_routes`` is not big enough to contain all the available routes
the subdevice exposes, drivers return the ENOSPC error code and adjust the
value of the ``num_routes`` field. Application should then reserve enough memory
for all the route entries and call ``VIDIOC_SUBDEV_G_ROUTING`` again.
The ``len_routes`` field indicates the number of routes that can fit in the
``routes`` array allocated by userspace. It is set by applications for both
ioctls to indicate how many routes the kernel can return, and is never modified
by the kernel.
On a successful ``VIDIOC_SUBDEV_G_ROUTING`` call the driver updates the
``num_routes`` field to reflect the actual number of routes returned.
The ``num_routes`` field indicates the number of routes in the routing
table. For ``VIDIOC_SUBDEV_S_ROUTING``, it is set by userspace to the number of
routes that the application stored in the ``routes`` array. For both ioctls, it
is returned by the kernel and indicates how many routes are stored in the
subdevice routing table. This may be smaller or larger than the value of
``num_routes`` set by the application for ``VIDIOC_SUBDEV_S_ROUTING``, as
drivers may adjust the requested routing table.
The kernel can return a ``num_routes`` value larger than ``len_routes`` from
both ioctls. This indicates thare are more routes in the routing table than fits
the ``routes`` array. In this case, the ``routes`` array is filled by the kernel
with the first ``len_routes`` entries of the subdevice routing table. This is
not considered to be an error, and the ioctl call succeeds. If the applications
wants to retrieve the missing routes, it can issue a new
``VIDIOC_SUBDEV_G_ROUTING`` call with a large enough ``routes`` array.
``VIDIOC_SUBDEV_S_ROUTING`` may return more routes than the user provided in
``num_routes`` field due to e.g. hardware properties.
.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
@ -74,6 +89,9 @@ On a successful ``VIDIOC_SUBDEV_G_ROUTING`` call the driver updates the
- ``which``
- Routing table to be accessed, from enum
:ref:`v4l2_subdev_format_whence <v4l2-subdev-format-whence>`.
* - __u32
- ``len_routes``
- The length of the array (as in memory reserved for the array)
* - struct :c:type:`v4l2_subdev_route`
- ``routes[]``
- Array of struct :c:type:`v4l2_subdev_route` entries
@ -81,7 +99,7 @@ On a successful ``VIDIOC_SUBDEV_G_ROUTING`` call the driver updates the
- ``num_routes``
- Number of entries of the routes array
* - __u32
- ``reserved``\ [5]
- ``reserved``\ [11]
- Reserved for future extensions. Applications and drivers must set
the array to zero.

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@ -3201,13 +3201,13 @@ static int check_array_args(unsigned int cmd, void *parg, size_t *array_size,
case VIDIOC_SUBDEV_S_ROUTING: {
struct v4l2_subdev_routing *routing = parg;
if (routing->num_routes > 256)
if (routing->len_routes > 256)
return -E2BIG;
*user_ptr = u64_to_user_ptr(routing->routes);
*kernel_ptr = (void **)&routing->routes;
*array_size = sizeof(struct v4l2_subdev_route)
* routing->num_routes;
* routing->len_routes;
ret = 1;
break;
}

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@ -960,14 +960,10 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg,
krouting = &state->routing;
if (routing->num_routes < krouting->num_routes) {
routing->num_routes = krouting->num_routes;
return -ENOSPC;
}
memcpy((struct v4l2_subdev_route *)(uintptr_t)routing->routes,
krouting->routes,
krouting->num_routes * sizeof(*krouting->routes));
min(krouting->num_routes, routing->len_routes) *
sizeof(*krouting->routes));
routing->num_routes = krouting->num_routes;
return 0;
@ -989,6 +985,9 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg,
if (routing->which != V4L2_SUBDEV_FORMAT_TRY && ro_subdev)
return -EPERM;
if (routing->num_routes > routing->len_routes)
return -EINVAL;
memset(routing->reserved, 0, sizeof(routing->reserved));
for (i = 0; i < routing->num_routes; ++i) {
@ -1015,6 +1014,7 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg,
}
krouting.num_routes = routing->num_routes;
krouting.len_routes = routing->len_routes;
krouting.routes = routes;
return v4l2_subdev_call(sd, pad, set_routing, state,

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@ -714,12 +714,14 @@ struct v4l2_subdev_stream_configs {
/**
* struct v4l2_subdev_krouting - subdev routing table
*
* @len_routes: length of routes array, in routes
* @num_routes: number of routes
* @routes: &struct v4l2_subdev_route
*
* This structure contains the routing table for a subdev.
*/
struct v4l2_subdev_krouting {
unsigned int len_routes;
unsigned int num_routes;
struct v4l2_subdev_route *routes;
};

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@ -228,15 +228,19 @@ struct v4l2_subdev_route {
* struct v4l2_subdev_routing - Subdev routing information
*
* @which: configuration type (from enum v4l2_subdev_format_whence)
* @num_routes: the total number of routes in the routes array
* @len_routes: the length of the routes array, in routes; set by the user, not
* modified by the kernel
* @routes: pointer to the routes array
* @num_routes: the total number of routes, possibly more than fits in the
* routes array
* @reserved: drivers and applications must zero this array
*/
struct v4l2_subdev_routing {
__u32 which;
__u32 num_routes;
__u32 len_routes;
__u64 routes;
__u32 reserved[6];
__u32 num_routes;
__u32 reserved[11];
};
/*