On Mon, 2019-02-18 at 17:15 -0300, Ezequiel Garcia wrote:
> Currently, the v4l2 control code is a bit silent on errors.
> To ease debugging of the control logic, add debug messages
> on (hopefully) most of the error paths.
>
I'm thinking some of these could receive a struct video_device,
and so use it to print the device node name.
I'll explore that and try to get a v2.
Thanks,
Eze
> Signed-off-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>
> ---
> drivers/media/v4l2-core/v4l2-ctrls.c | 63 +++++++++++++++++++++++-----
> include/media/v4l2-ioctl.h | 2 +
> 2 files changed, 54 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
> index 99308dac2daa..c9f4e00f2229 100644
> --- a/drivers/media/v4l2-core/v4l2-ctrls.c
> +++ b/drivers/media/v4l2-core/v4l2-ctrls.c
> @@ -18,6 +18,8 @@
> Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
> */
>
> +#define pr_fmt(fmt) "v4l2-ctrls: " fmt
> +
> #include <linux/ctype.h>
> #include <linux/mm.h>
> #include <linux/slab.h>
> @@ -28,6 +30,14 @@
> #include <media/v4l2-event.h>
> #include <media/v4l2-dev.h>
>
> +extern unsigned int videodev_debug;
> +
> +#define dprintk(fmt, arg...) do { \
> + if (videodev_debug & V4L2_DEV_DEBUG_CTRL) \
> + printk(KERN_DEBUG pr_fmt("%s: " fmt), \
> + __func__, ##arg); \
> +} while (0)
> +
> #define has_op(master, op) \
> (master->ops && master->ops->op)
> #define call_op(master, op) \
> @@ -1952,8 +1962,11 @@ static int validate_new(const struct v4l2_ctrl *ctrl, union v4l2_ctrl_ptr p_new)
> unsigned idx;
> int err = 0;
>
> - for (idx = 0; !err && idx < ctrl->elems; idx++)
> + for (idx = 0; !err && idx < ctrl->elems; idx++) {
> err = ctrl->type_ops->validate(ctrl, idx, p_new);
> + if (err)
> + dprintk("failed to validate control id 0x%x (%d)\n", ctrl->id, err);
> + }
> return err;
> }
>
> @@ -3136,20 +3149,28 @@ static int prepare_ext_ctrls(struct v4l2_ctrl_handler *hdl,
> if (cs->which &&
> cs->which != V4L2_CTRL_WHICH_DEF_VAL &&
> cs->which != V4L2_CTRL_WHICH_REQUEST_VAL &&
> - V4L2_CTRL_ID2WHICH(id) != cs->which)
> + V4L2_CTRL_ID2WHICH(id) != cs->which) {
> + dprintk("invalid which 0x%x or control id 0x%x\n", cs->which, id);
> return -EINVAL;
> + }
>
> /* Old-style private controls are not allowed for
> extended controls */
> - if (id >= V4L2_CID_PRIVATE_BASE)
> + if (id >= V4L2_CID_PRIVATE_BASE) {
> + dprintk("old-style private controls not allowed for extended controls\n");
> return -EINVAL;
> + }
> ref = find_ref_lock(hdl, id);
> - if (ref == NULL)
> + if (ref == NULL) {
> + dprintk("cannot find control id 0x%x\n", id);
> return -EINVAL;
> + }
> h->ref = ref;
> ctrl = ref->ctrl;
> - if (ctrl->flags & V4L2_CTRL_FLAG_DISABLED)
> + if (ctrl->flags & V4L2_CTRL_FLAG_DISABLED) {
> + dprintk("control id 0x%x is disabled\n", id);
> return -EINVAL;
> + }
>
> if (ctrl->cluster[0]->ncontrols > 1)
> have_clusters = true;
> @@ -3159,10 +3180,16 @@ static int prepare_ext_ctrls(struct v4l2_ctrl_handler *hdl,
> unsigned tot_size = ctrl->elems * ctrl->elem_size;
>
> if (c->size < tot_size) {
> + /*
> + * In the get case the application first queries
> + * to obtain the size of the control.
> + */
> if (get) {
> c->size = tot_size;
> return -ENOSPC;
> }
> + dprintk("pointer control id 0x%x size too small, %d bytes but %d bytes needed\n",
> + id, c->size, tot_size);
> return -EFAULT;
> }
> c->size = tot_size;
> @@ -3534,16 +3561,20 @@ static int validate_ctrls(struct v4l2_ext_controls *cs,
>
> cs->error_idx = i;
>
> - if (ctrl->flags & V4L2_CTRL_FLAG_READ_ONLY)
> + if (ctrl->flags & V4L2_CTRL_FLAG_READ_ONLY) {
> + dprintk("control id 0x%x is read-only\n", ctrl->id);
> return -EACCES;
> + }
> /* This test is also done in try_set_control_cluster() which
> is called in atomic context, so that has the final say,
> but it makes sense to do an up-front check as well. Once
> an error occurs in try_set_control_cluster() some other
> controls may have been set already and we want to do a
> best-effort to avoid that. */
> - if (set && (ctrl->flags & V4L2_CTRL_FLAG_GRABBED))
> + if (set && (ctrl->flags & V4L2_CTRL_FLAG_GRABBED)) {
> + dprintk("control id 0x%x is grabbed, cannot set\n", ctrl->id);
> return -EBUSY;
> + }
> /*
> * Skip validation for now if the payload needs to be copied
> * from userspace into kernelspace. We'll validate those later.
> @@ -3588,13 +3619,17 @@ static int try_set_ext_ctrls_common(struct v4l2_fh *fh,
> cs->error_idx = cs->count;
>
> /* Default value cannot be changed */
> - if (cs->which == V4L2_CTRL_WHICH_DEF_VAL)
> + if (cs->which == V4L2_CTRL_WHICH_DEF_VAL) {
> + dprintk("cannot change default value\n");
> return -EINVAL;
> + }
>
> cs->which = V4L2_CTRL_ID2WHICH(cs->which);
>
> - if (hdl == NULL)
> + if (hdl == NULL) {
> + dprintk("invalid null control handler\n");
> return -EINVAL;
> + }
>
> if (cs->count == 0)
> return class_check(hdl, cs->which);
> @@ -3700,21 +3735,27 @@ static int try_set_ext_ctrls(struct v4l2_fh *fh,
> int ret;
>
> if (cs->which == V4L2_CTRL_WHICH_REQUEST_VAL) {
> - if (!mdev || cs->request_fd < 0)
> + if (!mdev || cs->request_fd < 0) {
> + dprintk("missing media device or invalid request fd\n");
> return -EINVAL;
> + }
>
> req = media_request_get_by_fd(mdev, cs->request_fd);
> - if (IS_ERR(req))
> + if (IS_ERR(req)) {
> + dprintk("cannot find request fd %d\n", cs->request_fd);
> return PTR_ERR(req);
> + }
>
> ret = media_request_lock_for_update(req);
> if (ret) {
> + dprintk("cannot lock request fd %d\n", cs->request_fd);
> media_request_put(req);
> return ret;
> }
>
> obj = v4l2_ctrls_find_req_obj(hdl, req, set);
> if (IS_ERR(obj)) {
> + dprintk("cannot find request object for request fd %d\n", cs->request_fd);
> media_request_unlock_for_update(req);
> media_request_put(req);
> return PTR_ERR(obj);
> diff --git a/include/media/v4l2-ioctl.h b/include/media/v4l2-ioctl.h
> index 8533ece5026e..0ecd4e3e76a4 100644
> --- a/include/media/v4l2-ioctl.h
> +++ b/include/media/v4l2-ioctl.h
> @@ -612,6 +612,8 @@ struct v4l2_ioctl_ops {
> #define V4L2_DEV_DEBUG_STREAMING 0x08
> /* Log poll() */
> #define V4L2_DEV_DEBUG_POLL 0x10
> +/* Log controls */
> +#define V4L2_DEV_DEBUG_CTRL 0x20
>
> /* Video standard functions */
>
