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.
>>
>> 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
