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usb: gadget: uvc: Make bmControls attr read/write 

For the Processing Unit and Camera Terminal descriptors defined in
the UVC Gadget we currently hard-code values into their bmControls
fields, which enumerates which controls the gadget is able to
support. This isn't appropriate since only the userspace companion
program to the kernel driver will know which controls are supported.
Make the configfs attributes that point to those fields read/write
so userspace can set them to appropriate values.

Document the new behaviour at the same time so the functionality is
clear.

Signed-off-by: Daniel Scally <dan.scally@ideasonboard.com>
Link: https://lore.kernel.org/r/20230309105825.216745-1-dan.scally@ideasonboard.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Daniel Scally 2023-03-09 10:58:25 +00:00 committed by Greg Kroah-Hartman
parent 0d6a119cec
commit 7bf1c56a90
3 changed files with 149 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
Documentation/ABI/testing/configfs-usb-gadget-uvc
View File

@ -76,7 +76,7 @@ Date: Dec 2014
KernelVersion: 4.0
Description: Default camera terminal descriptors
All attributes read only:
All attributes read only except bmControls, which is read/write:
======================== ====================================
bmControls bitmap specifying which controls are
@ -101,7 +101,7 @@ Date: Dec 2014
KernelVersion: 4.0
Description: Default processing unit descriptors
All attributes read only:
All attributes read only except bmControls, which is read/write:
=============== ========================================
iProcessing index of string descriptor

28
Documentation/usb/gadget_uvc.rst
View File

@ -275,6 +275,34 @@ out with 0x00, for example:
bNrInPins and baSourceID function in the same way.
Configuring Supported Controls for Camera Terminal and Processing Unit
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The Camera Terminal and Processing Units in the UVC chain also have bmControls
attributes which function similarly to the same field in an Extension Unit.
Unlike XUs however, the meaning of the bitflag for these units is defined in
the UVC specification; you should consult the "Camera Terminal Descriptor" and
"Processing Unit Descriptor" sections for an enumeration of the flags.
.. code-block:: bash
# Set the Processing Unit's bmControls, flagging Brightness, Contrast
# and Hue as available controls:
echo 0x05 > $FUNCTION/control/processing/default/bmControls
# Set the Camera Terminal's bmControls, flagging Focus Absolute and
# Focus Relative as available controls:
echo 0x60 > $FUNCTION/control/terminal/camera/default/bmControls
If you do not set these fields then by default the Auto-Exposure Mode control
for the Camera Terminal and the Brightness control for the Processing Unit will
be flagged as available; if they are not supported you should set the field to
0x00.
Note that the size of the bmControls field for a Camera Terminal or Processing
Unit is fixed by the UVC specification, and so the bControlSize attribute is
read-only here.
Custom Strings Support
~~~~~~~~~~~~~~~~~~~~~~

121
drivers/usb/gadget/function/uvc_configfs.c
View File

@ -334,6 +334,64 @@ UVCG_DEFAULT_PROCESSING_ATTR(i_processing, iProcessing, 8);
#undef UVCG_DEFAULT_PROCESSING_ATTR
static ssize_t uvcg_default_processing_bm_controls_store(
struct config_item *item, const char *page, size_t len)
{
struct config_group *group = to_config_group(item);
struct mutex *su_mutex = &group->cg_subsys->su_mutex;
struct uvc_processing_unit_descriptor *pd;
struct config_item *opts_item;
struct f_uvc_opts *opts;
u8 *bm_controls, *tmp;
unsigned int i;
int ret, n = 0;
mutex_lock(su_mutex);
opts_item = group->cg_item.ci_parent->ci_parent->ci_parent;
opts = to_f_uvc_opts(opts_item);
pd = &opts->uvc_processing;
mutex_lock(&opts->lock);
if (opts->refcnt) {
ret = -EBUSY;
goto unlock;
}
ret = __uvcg_iter_item_entries(page, len, __uvcg_count_item_entries, &n,
sizeof(u8));
if (ret)
goto unlock;
if (n > pd->bControlSize) {
ret = -EINVAL;
goto unlock;
}
tmp = bm_controls = kcalloc(n, sizeof(u8), GFP_KERNEL);
if (!bm_controls) {
ret = -ENOMEM;
goto unlock;
}
ret = __uvcg_iter_item_entries(page, len, __uvcg_fill_item_entries, &tmp,
sizeof(u8));
if (ret)
goto free_mem;
for (i = 0; i < n; i++)
pd->bmControls[i] = bm_controls[i];
ret = len;
free_mem:
kfree(bm_controls);
unlock:
mutex_unlock(&opts->lock);
mutex_unlock(su_mutex);
return ret;
}
static ssize_t uvcg_default_processing_bm_controls_show(
struct config_item *item, char *page)
{
@ -363,7 +421,7 @@ static ssize_t uvcg_default_processing_bm_controls_show(
return result;
}
UVC_ATTR_RO(uvcg_default_processing_, bm_controls, bmControls);
UVC_ATTR(uvcg_default_processing_, bm_controls, bmControls);
static struct configfs_attribute *uvcg_default_processing_attrs[] = {
&uvcg_default_processing_attr_b_unit_id,
@ -445,6 +503,65 @@ UVCG_DEFAULT_CAMERA_ATTR(w_ocular_focal_length, wOcularFocalLength,
#undef UVCG_DEFAULT_CAMERA_ATTR
static ssize_t uvcg_default_camera_bm_controls_store(
struct config_item *item, const char *page, size_t len)
{
struct config_group *group = to_config_group(item);
struct mutex *su_mutex = &group->cg_subsys->su_mutex;
struct uvc_camera_terminal_descriptor *cd;
struct config_item *opts_item;
struct f_uvc_opts *opts;
u8 *bm_controls, *tmp;
unsigned int i;
int ret, n = 0;
mutex_lock(su_mutex);
opts_item = group->cg_item.ci_parent->ci_parent->ci_parent->
ci_parent;
opts = to_f_uvc_opts(opts_item);
cd = &opts->uvc_camera_terminal;
mutex_lock(&opts->lock);
if (opts->refcnt) {
ret = -EBUSY;
goto unlock;
}
ret = __uvcg_iter_item_entries(page, len, __uvcg_count_item_entries, &n,
sizeof(u8));
if (ret)
goto unlock;
if (n > cd->bControlSize) {
ret = -EINVAL;
goto unlock;
}
tmp = bm_controls = kcalloc(n, sizeof(u8), GFP_KERNEL);
if (!bm_controls) {
ret = -ENOMEM;
goto unlock;
}
ret = __uvcg_iter_item_entries(page, len, __uvcg_fill_item_entries, &tmp,
sizeof(u8));
if (ret)
goto free_mem;
for (i = 0; i < n; i++)
cd->bmControls[i] = bm_controls[i];
ret = len;
free_mem:
kfree(bm_controls);
unlock:
mutex_unlock(&opts->lock);
mutex_unlock(su_mutex);
return ret;
}
static ssize_t uvcg_default_camera_bm_controls_show(
struct config_item *item, char *page)
{
@ -474,7 +591,7 @@ static ssize_t uvcg_default_camera_bm_controls_show(
return result;
}
UVC_ATTR_RO(uvcg_default_camera_, bm_controls, bmControls);
UVC_ATTR(uvcg_default_camera_, bm_controls, bmControls);
static struct configfs_attribute *uvcg_default_camera_attrs[] = {
&uvcg_default_camera_attr_b_terminal_id,