On Wed, Sep 27, 2023 at 09:19:46AM +0200, Hans Verkuil wrote:
> On 27/09/2023 01:29, Nicolas Dufresne wrote:
> > Le vendredi 22 septembre 2023 à 09:33 +0200, Hans Verkuil a écrit :
> >> On 21/09/2023 21:11, Nicolas Dufresne wrote:
> >>> Le mercredi 20 septembre 2023 à 17:13 +0200, Hans Verkuil a écrit :
> >>>> On 15/09/2023 23:11, Sebastian Fricke wrote:
> >>>>> From: Nas Chung <nas.chung@xxxxxxxxxxxxxxx>
> >>>>>
> >>>>> Add the decoder and encoder implementing the v4l2
> >>>>> API. This patch also adds the Makefile and the VIDEO_WAVE_VPU config
> >>>>>
> >>>>> Signed-off-by: Sebastian Fricke <sebastian.fricke@xxxxxxxxxxxxx>
> >>>>> Signed-off-by: Nicolas Dufresne <nicolas.dufresne@xxxxxxxxxxxxx>
> >>>>> Signed-off-by: Robert Beckett <bob.beckett@xxxxxxxxxxxxx>
> >>>>> Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@xxxxxxxxxxxxx>
> >>>>> Signed-off-by: Nas Chung <nas.chung@xxxxxxxxxxxxxxx>
> >>>>> ---
> >>>>> drivers/media/platform/chips-media/Kconfig | 1 +
> >>>>> drivers/media/platform/chips-media/Makefile | 1 +
> >>>>> drivers/media/platform/chips-media/wave5/Kconfig | 12 +
> >>>>> drivers/media/platform/chips-media/wave5/Makefile | 10 +
> >>>>> .../platform/chips-media/wave5/wave5-helper.c | 196 ++
> >>>>> .../platform/chips-media/wave5/wave5-helper.h | 30 +
> >>>>> .../platform/chips-media/wave5/wave5-vpu-dec.c | 1965 ++++++++++++++++++++
> >>>>> .../platform/chips-media/wave5/wave5-vpu-enc.c | 1825 ++++++++++++++++++
> >>>>> .../media/platform/chips-media/wave5/wave5-vpu.c | 331 ++++
> >>>>> .../media/platform/chips-media/wave5/wave5-vpu.h | 83 +
> >>>>> 10 files changed, 4454 insertions(+)
> >>>>>
> >>
> >> <snip>
> >>
> >>>>> +static int wave5_vpu_dec_set_eos_on_firmware(struct vpu_instance *inst)
> >>>>> +{
> >>>>> + int ret;
> >>>>> +
> >>>>> + ret = wave5_vpu_dec_update_bitstream_buffer(inst, 0);
> >>>>> + if (ret) {
> >>>>> + dev_err(inst->dev->dev,
> >>>>> + "Setting EOS for the bitstream, fail: %d\n", ret);
> >>>>
> >>>> Is this an error due to a driver problem, or because a bad bitstream is
> >>>> fed from userspace? In the first case, dev_err would be right, in the
> >>>> second dev_dbg would be more appropriate. Bad userspace input should not
> >>>> spam the kernel log in general.
> >>>
> >>> Its the first. To set the EOS flag, a command is sent to the firmware. That
> >>> command may never return (timeout) or may report an error. For this specific
> >>> command, if that happens we are likely facing firmware of driver problem (or
> >>> both).
> >>
> >> OK, I'd add that as a comment here as this is unexpected behavior.
> >>
> >>>
> >>>>
> >>>>> + return ret;
> >>>>> + }
> >>>>> + return 0;
> >>>>> +}
> >>
> >> <snip>
> >>
> >>>>> +static int wave5_vpu_dec_create_bufs(struct file *file, void *priv,
> >>>>> + struct v4l2_create_buffers *create)
> >>>>> +{
> >>>>> + struct v4l2_format *f = &create->format;
> >>>>> +
> >>>>> + if (f->type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
> >>>>> + return -ENOTTY;
> >>>>
> >>>> Huh? Why is this needed?
> >>>
> >>> Minimally a comment should be added. The why is that we support CREATE_BUF for
> >>> OUTPUT queue (bitstream) but not for CAPTURE queues. This is simply not
> >>> supported by Wave5 firmware. Do you have any suggestion how this asymmetry can
> >>> be implemented better ?
> >>
> >> Certainly not with ENOTTY: the ioctl exists, it is just not supported for
> >> CAPTURE queues.
> >>
> >> How about -EPERM? And document this error as well in the VIDIOC_CREATE_BUFS
> >> documentation. And you want a dev_dbg here too.
> >
> > The suggestion cannot be used since there is documentation for that one already,
> > and it does not match "unsupported".
> >
> > "Permission denied. Can be returned if the device needs write permission, or
> > some special capabilities is needed (e. g. root)"
> >
> > What about using the most logical error code, which name is actually obvious,
> > like ENOTSUP ?
> >
> > #define ENOTSUPP 524 /* Operation is not supported */
> >
>
> Let's go with EOPNOTSUPP. That seems to be the more commonly used error
> code in drivers.
Hi Hans,
Sorry to belabour this issue but when I change the return value
to EOPNOTSUPP, it now causes v4l2-compliance to fail because
v4l2-test-buffers.cpp expects ENOTTY if CREATE_BUFS is not supported.
We didn't get this warning before because there was a typo in the
buffer check and it was only checking for single-planar buffers.
How would you prefer to handle this? The options seem like
keep ENOTTY in this driver or
patch v4l2-compliance to warn if it also receives EOPNOTSUPP?
>
> >>
> >> So I would propose that EPERM is returned if CREATE_BUFS is only supported
> >> for for one of the two queues of an M2M device.
> >
> > Note that userspace does not care of the difference between an ioctl not being
> > implemented at all or not being implement for one queue. GStreamer have been
> > testing with both queue type for couple of years now. Adding this distinction is
> > just leaking an implementation details to userspace. I'm fine to just do what
> > you'd like, just stating the obvious that while it may look logical inside the
> > kernel, its a bit of a non-sense for our users.
>
> I don't agree with that. If an ioctl returns ENOTTY, then userspace can be certain
> that that ioctl is not implemented for the given file descriptor. That's not the case
> here: it is implemented, the operation is just not supported for one of the queues.
>
> Regards,
>
> Hans
