Hi Sakari, On Fri, Feb 22, 2019 at 01:49:36AM +0200, Sakari Ailus wrote: > Hi Jacopo, > > On Thu, Feb 21, 2019 at 03:59:20PM +0100, Jacopo Mondi wrote: > > Hi Sakari, Laurent, Niklas, > > (another) quick question, but a different one :) > > > > On Wed, Jan 16, 2019 at 01:51:45AM +0200, Laurent Pinchart wrote: > > > Hi Niklas, > > > > > > Thank you for the patch. > > > > > > On Fri, Nov 02, 2018 at 12:31:30AM +0100, Niklas Söderlund wrote: > > > > From: Laurent Pinchart > > > > > > > > Signed-off-by: Laurent Pinchart > > > > Signed-off-by: Michal Simek > > > > > > > > - Add sink and source streams for multiplexed links > > > > - Copy the argument back in case of an error. This is needed to let the > > > > caller know the number of routes. > > > > > > > > Signed-off-by: Sakari Ailus > > > > Reviewed-by: Niklas Söderlund > > > > --- > > > > drivers/media/v4l2-core/v4l2-ioctl.c | 20 +++++++++++++- > > > > drivers/media/v4l2-core/v4l2-subdev.c | 28 +++++++++++++++++++ > > > > include/media/v4l2-subdev.h | 7 +++++ > > > > include/uapi/linux/v4l2-subdev.h | 40 +++++++++++++++++++++++++++ > > > > > > Missing documentation :-( > > > > > > > 4 files changed, 94 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c > > > > index 7de041bae84fb2f2..40406acb51ec0906 100644 > > > > --- a/drivers/media/v4l2-core/v4l2-ioctl.c > > > > +++ b/drivers/media/v4l2-core/v4l2-ioctl.c > > > > @@ -19,6 +19,7 @@ > > > > #include > > > > #include > > > > > > > > +#include > > > > #include > > > > > > > > #include > > > > @@ -2924,6 +2925,23 @@ static int check_array_args(unsigned int cmd, void *parg, size_t *array_size, > > > > } > > > > break; > > > > } > > > > + > > > > + case VIDIOC_SUBDEV_G_ROUTING: > > > > + case VIDIOC_SUBDEV_S_ROUTING: { > > > > + struct v4l2_subdev_routing *route = parg; > > > > + > > > > + if (route->num_routes > 0) { > > > > + if (route->num_routes > 256) > > > > + return -EINVAL; > > > > + > > > > + *user_ptr = (void __user *)route->routes; > > > > + *kernel_ptr = (void *)&route->routes; > > > > + *array_size = sizeof(struct v4l2_subdev_route) > > > > + * route->num_routes; > > > > + ret = 1; > > > > + } > > > > + break; > > > > + } > > > > } > > > > > > > > return ret; > > > > @@ -3033,7 +3051,7 @@ video_usercopy(struct file *file, unsigned int cmd, unsigned long arg, > > > > * Some ioctls can return an error, but still have valid > > > > * results that must be returned. > > > > */ > > > > - if (err < 0 && !always_copy) > > > > + if (err < 0 && !always_copy && cmd != VIDIOC_SUBDEV_G_ROUTING) > > > > > > This seems like a hack. Shouldn't VIDIOC_SUBDEV_G_ROUTING set > > > always_copy instead ? > > > > > > > goto out; > > > > > > > > out_array_args: > > > > diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c > > > > index 792f41dffe2329b9..1d3b37cf548fa533 100644 > > > > --- a/drivers/media/v4l2-core/v4l2-subdev.c > > > > +++ b/drivers/media/v4l2-core/v4l2-subdev.c > > > > @@ -516,7 +516,35 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg) > > > > > > > > case VIDIOC_SUBDEV_QUERYSTD: > > > > return v4l2_subdev_call(sd, video, querystd, arg); > > > > + > > > > + case VIDIOC_SUBDEV_G_ROUTING: > > > > + return v4l2_subdev_call(sd, pad, get_routing, arg); > > > > + > > > > + case VIDIOC_SUBDEV_S_ROUTING: { > > > > + struct v4l2_subdev_routing *route = arg; > > > > + unsigned int i; > > > > + > > > > + if (route->num_routes > sd->entity.num_pads) > > > > + return -EINVAL; > > > > + > > > > + for (i = 0; i < route->num_routes; ++i) { > > > > How have you envisioned the number of routes to be negotiated with > > applications? I'm writing the documentation for this ioctl, and I > > would like to insert this part as well. > > > > Would a model like the one implemented in G_TOPOLOGY work in your > > opinion? In my understanding, at the moment applications do not have a > > way to reserve a known number of routes entries, but would likely > > reserve 'enough(tm)' (ie 256) and pass them to the G_ROUTING ioctl that the > > first time will likely adjust the number of num_routes and return -ENOSPC. > > > > Wouldn't it work to make the IOCTL behave in a way that it > > expects the first call to be performed with (num_routes == 0) and no routes > > entries reserved, and just adjust 'num_routes' in that case? > > So that applications should call G_ROUTING a first time with > > num_routes = 0, get back the number of routes entries, reserve memory > > for them, and then call G_ROUTING again to have the entries populated > > by the driver. Do you have different ideas or was this the intended > > behavior already? > > I think whenever the number of routes isn't enough to return them all, the > IOCTL should return -ENOSPC, and set the actual number of routes there. Not > just zero. The user could e.g. try with a static allocation of some, and > allocate memory if the static allocation turns not to be enough. I see. That's fine, I just wanted to make sure I was not missing something... Fine with me if num_routes is not adequate, it should be corrected by the driver and -ENOSPC returned. How applications deal with allocation is up to them (even if documentation might suggest to perform and "call with 0, allocate, call again" sequence as a way to ease this) > > Btw. the idea behind S_ROUTING behaviour was to allow multiple users to > work on a single sub-device without having to know about each other. That's > why there are flags to tell which routes are enabled and which are not. > > I'll be better available tomorrow, let's discuss e.g. on #v4l then. > Unfortunately I won't too much today :) I'll keep pinging in the next days then, sorry about this :p Thanks j > -- > Sakari Ailus > sakari.ailus@linux.intel.com