Re: [PATCH 11/15] media: intel/ipu6: input system video capture nodes

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Bingbu,

On Wed, Dec 20, 2023 at 11:42:47AM +0800, Bingbu Cao wrote:
> On 7/27/23 3:15 PM, bingbu.cao@intel.com wrote:
> > From: Bingbu Cao <bingbu.cao@intel.com>
> > 
> > Register v4l2 video device and setup the vb2 queue to
> > support basic video capture. Video streaming callback
> > will trigger the input system driver to construct a
> > input system stream configuration for firmware based on
> > data type and stream ID and then queue buffers to firmware
> > to do capture.
> > 
> > Signed-off-by: Bingbu Cao <bingbu.cao@intel.com>
> > ---
> >  .../media/pci/intel/ipu6/ipu6-isys-queue.c    |  864 ++++++++++++
> >  .../media/pci/intel/ipu6/ipu6-isys-queue.h    |   97 ++
> >  .../media/pci/intel/ipu6/ipu6-isys-video.c    | 1237 +++++++++++++++++
> >  .../media/pci/intel/ipu6/ipu6-isys-video.h    |  133 ++
> >  4 files changed, 2331 insertions(+)
> >  create mode 100644 drivers/media/pci/intel/ipu6/ipu6-isys-queue.c
> >  create mode 100644 drivers/media/pci/intel/ipu6/ipu6-isys-queue.h
> >  create mode 100644 drivers/media/pci/intel/ipu6/ipu6-isys-video.c
> >  create mode 100644 drivers/media/pci/intel/ipu6/ipu6-isys-video.h
> > 
> > diff --git a/drivers/media/pci/intel/ipu6/ipu6-isys-queue.c b/drivers/media/pci/intel/ipu6/ipu6-isys-queue.c
> > new file mode 100644
> > index 000000000000..c683a1b7c91f
> --snip--
> 
> > +static const struct vb2_ops ipu6_isys_queue_ops = {
> > +	.queue_setup = queue_setup,
> > +	.wait_prepare = vb2_ops_wait_prepare,
> > +	.wait_finish = vb2_ops_wait_finish,
> > +	.buf_prepare = buf_prepare,
> > +	.start_streaming = start_streaming,
> > +	.stop_streaming = stop_streaming,
> > +	.buf_queue = buf_queue,
> > +};
> > +
> > +int ipu6_isys_queue_init(struct ipu6_isys_queue *aq)
> > +{
> > +	struct ipu6_isys *isys = ipu6_isys_queue_to_video(aq)->isys;
> > +	struct ipu6_isys_video *av = ipu6_isys_queue_to_video(aq);
> > +	int ret;
> > +
> > +	/* no support for userptr */
> > +	if (!aq->vbq.io_modes)
> > +		aq->vbq.io_modes = VB2_MMAP | VB2_DMABUF;
> 
> 
> There are some improvement and bug fixing in vb2 USERPTR in the past
> months, I remember someone told me the userptr is buggy, I remove the
> USERPTR support from current IPU6 ISYS driver. However, there is some
> userspace application still need the USERPTR, so I am not sure whether
> I should add it back. Do you have any suggestion?

Modern applications should really not use USERPTR, so I wouldn't add it
back. It's still a deprecated interface.

In the vast majority of cases, the PSYS will be used through libcamera,
which doesn't use USERPTR. I expect the remaining use cases to be very
specialized and not rely on pre-existing code that would require
USERPTR.

-- 
Regards,

Laurent Pinchart