linux-kernel - Re: [PATCH] media: venus: add support for key frame

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Date:   Wed, 24 Oct 2018 19:07:45 +0530
From:   mgottam@...eaurora.org
To:     Tomasz Figa <tfiga@...omium.org>
Cc:     Alexandre Courbot <acourbot@...omium.org>,
        Stanimir Varbanov <stanimir.varbanov@...aro.org>,
        Hans Verkuil <hverkuil@...all.nl>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        vgarodia@...eaurora.org
Subject: Re: [PATCH] media: venus: add support for key frame

On 2018-10-23 08:37, Tomasz Figa wrote:
> On Mon, Oct 22, 2018 at 3:15 PM Alexandre Courbot 
> <acourbot@...omium.org> wrote:
>> 
>> On Fri, Oct 12, 2018 at 5:10 PM Stanimir Varbanov
>> <stanimir.varbanov@...aro.org> wrote:
>> >
>> >
>> >
>> > On 10/12/2018 11:06 AM, Alexandre Courbot wrote:
>> > > On Fri, Oct 12, 2018 at 4:37 PM Stanimir Varbanov
>> > > <stanimir.varbanov@...aro.org> wrote:
>> > >>
>> > >> Hi Alex,
>> > >>
>> > >> On 10/12/2018 08:26 AM, Alexandre Courbot wrote:
>> > >>> On Tue, Oct 9, 2018 at 4:54 PM Malathi Gottam <mgottam@...eaurora.org> wrote:
>> > >>>>
>> > >>>> When client requests for a keyframe, set the property
>> > >>>> to hardware to generate the sync frame.
>> > >>>>
>> > >>>> Signed-off-by: Malathi Gottam <mgottam@...eaurora.org>
>> > >>>> ---
>> > >>>>  drivers/media/platform/qcom/venus/venc_ctrls.c | 13 +++++++++++++
>> > >>>>  1 file changed, 13 insertions(+)
>> > >>>>
>> > >>>> diff --git a/drivers/media/platform/qcom/venus/venc_ctrls.c b/drivers/media/platform/qcom/venus/venc_ctrls.c
>> > >>>> index 45910172..f332c8e 100644
>> > >>>> --- a/drivers/media/platform/qcom/venus/venc_ctrls.c
>> > >>>> +++ b/drivers/media/platform/qcom/venus/venc_ctrls.c
>> > >>>> @@ -81,6 +81,8 @@ static int venc_op_s_ctrl(struct v4l2_ctrl *ctrl)
>> > >>>>         struct venc_controls *ctr = &inst->controls.enc;
>> > >>>>         u32 bframes;
>> > >>>>         int ret;
>> > >>>> +       void *ptr;
>> > >>>> +       u32 ptype;
>> > >>>>
>> > >>>>         switch (ctrl->id) {
>> > >>>>         case V4L2_CID_MPEG_VIDEO_BITRATE_MODE:
>> > >>>> @@ -173,6 +175,14 @@ static int venc_op_s_ctrl(struct v4l2_ctrl *ctrl)
>> > >>>>
>> > >>>>                 ctr->num_b_frames = bframes;
>> > >>>>                 break;
>> > >>>> +       case V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME:
>> > >>>> +               ptype = HFI_PROPERTY_CONFIG_VENC_REQUEST_SYNC_FRAME;
>> > >>>> +               ret = hfi_session_set_property(inst, ptype, ptr);
>> > >>>
>> > >>> The test bot already said it, but ptr is passed to
>> > >>> hfi_session_set_property() uninitialized. And as can be expected the
>> > >>> call returns -EINVAL on my board.
>> > >>>
>> > >>> Looking at other uses of HFI_PROPERTY_CONFIG_VENC_REQUEST_SYNC_FRAME I
>> > >>> see that the packet sent to the firmware does not have room for an
>> > >>> argument, so I tried to pass NULL but got the same result.
>> > >>
>> > >> yes, because pdata cannot be NULL. I'd suggest to make a pointer to
>> > >> struct hfi_enable and pass it to the set_property function.
>> > >
>> > > FWIW I also tried doing this and got the same error, strange...
>> > >
>> >
>> > OK, when you calling the v4l control? It makes sense when you calling
>> > it, because set_property checks does the session is on START state (i.e.
>> > streamon on both queues).
>> 
>> Do you mean that the property won't be actually applied unless both
>> queues are streaming? In that case maybe it would make sense for the
>> driver to save controls set before that and apply them when the
>> conditions allow them to be effective?
> 
> Right. The driver cannot just drop a control setting on the floor if
> it's not ready to apply it.
> 
> However, the V4L2 control framework already provides a tool to handle 
> this:
>  - the driver can ignore any .s_ctrl() calls when it can't apply the 
> controls,
>  - the driver must call v4l2_ctrl_handler_setup() when it initialized
> the hardware, so that all the control values are applied in one go.
> 
> Best regards,
> Tomasz
Yes V4L2 control framework validates the ctrls before being set.

But these controls are initialized before session initialization. So 
s_ctrl tries to set property 
"HFI_PROPERTY_CONFIG_VENC_REQUEST_SYNC_FRAME" as a part of initializing 
all controls(session still in UNINIT state). But this is not any client 
request.

So we can keep a check to
1. ensure that its client requesting sync frame and
2. session in START state (both planes are streaming)

I will update the patch with these changes.