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Date:   Wed, 02 May 2018 19:34:58 +0530
From:   Vikash Garodia <vgarodia@codeaurora.org>
To:     Nicolas Dufresne <nicolas@ndufresne.ca>
Cc:     Stanimir Varbanov <stanimir.varbanov@linaro.org>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Hans Verkuil <hverkuil@xs4all.nl>, linux-media@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        linux-media-owner@vger.kernel.org
Subject: Re: [PATCH 26/28] venus: implementing multi-stream support
In-Reply-To: <427fce2a602af600a87434b8e70c4f6903708fb2.camel@ndufresne.ca>
References: <20180424124436.26955-1-stanimir.varbanov@linaro.org>
 <20180424124436.26955-27-stanimir.varbanov@linaro.org>
 <d3611ce941e71fd901cce70da89f9ab4@codeaurora.org>
 <427fce2a602af600a87434b8e70c4f6903708fb2.camel@ndufresne.ca>
Message-ID: <923055039e9439d35fa6d303266d54d7@codeaurora.org>
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On 2018-05-02 18:58, Nicolas Dufresne wrote:
> Le mercredi 02 mai 2018 à 13:10 +0530, Vikash Garodia a écrit :
>> Hello Stanimir,
>> 
>> On 2018-04-24 18:14, Stanimir Varbanov wrote:
>> > This is implementing a multi-stream decoder support. The multi
>> > stream gives an option to use the secondary decoder output
>> > with different raw format (or the same in case of crop).
>> >
>> > Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
>> > ---
>> >  drivers/media/platform/qcom/venus/core.h    |   1 +
>> >  drivers/media/platform/qcom/venus/helpers.c | 204
>> > +++++++++++++++++++++++++++-
>> >  drivers/media/platform/qcom/venus/helpers.h |   6 +
>> >  drivers/media/platform/qcom/venus/vdec.c    |  91 ++++++++++++-
>> >  drivers/media/platform/qcom/venus/venc.c    |   1 +
>> >  5 files changed, 299 insertions(+), 4 deletions(-)
>> >
>> > diff --git a/drivers/media/platform/qcom/venus/core.h
>> > b/drivers/media/platform/qcom/venus/core.h
>> > index 4d6c05f156c4..85e66e2dd672 100644
>> > --- a/drivers/media/platform/qcom/venus/core.h
>> > +++ b/drivers/media/platform/qcom/venus/core.h
>> > @@ -259,6 +259,7 @@ struct venus_inst {
>> >  	struct list_head list;
>> >  	struct mutex lock;
>> >  	struct venus_core *core;
>> > +	struct list_head dpbbufs;
>> >  	struct list_head internalbufs;
>> >  	struct list_head registeredbufs;
>> >  	struct list_head delayed_process;
>> > diff --git a/drivers/media/platform/qcom/venus/helpers.c
>> > b/drivers/media/platform/qcom/venus/helpers.c
>> > index ed569705ecac..87dcf9973e6f 100644
>> > --- a/drivers/media/platform/qcom/venus/helpers.c
>> > +++ b/drivers/media/platform/qcom/venus/helpers.c
>> > @@ -85,6 +85,112 @@ bool venus_helper_check_codec(struct venus_inst
>> > *inst, u32 v4l2_pixfmt)
>> >  }
>> >  EXPORT_SYMBOL_GPL(venus_helper_check_codec);
>> >
>> > +static int venus_helper_queue_dpb_bufs(struct venus_inst *inst)
>> > +{
>> > +	struct intbuf *buf;
>> > +	int ret = 0;
>> > +
>> > +	if (list_empty(&inst->dpbbufs))
>> > +		return 0;
>> > +
>> > +	list_for_each_entry(buf, &inst->dpbbufs, list) {
>> > +		struct hfi_frame_data fdata;
>> > +
>> > +		memset(&fdata, 0, sizeof(fdata));
>> > +		fdata.alloc_len = buf->size;
>> > +		fdata.device_addr = buf->da;
>> > +		fdata.buffer_type = buf->type;
>> > +
>> > +		ret = hfi_session_process_buf(inst, &fdata);
>> > +		if (ret)
>> > +			goto fail;
>> > +	}
>> > +
>> > +fail:
>> > +	return ret;
>> > +}
>> > +
>> > +int venus_helper_free_dpb_bufs(struct venus_inst *inst)
>> > +{
>> > +	struct intbuf *buf, *n;
>> > +
>> > +	if (list_empty(&inst->dpbbufs))
>> > +		return 0;
>> > +
>> > +	list_for_each_entry_safe(buf, n, &inst->dpbbufs, list) {
>> > +		list_del_init(&buf->list);
>> > +		dma_free_attrs(inst->core->dev, buf->size, buf-
>> > >va, buf->da,
>> > +			       buf->attrs);
>> > +		kfree(buf);
>> > +	}
>> > +
>> > +	INIT_LIST_HEAD(&inst->dpbbufs);
>> > +
>> > +	return 0;
>> > +}
>> > +EXPORT_SYMBOL_GPL(venus_helper_free_dpb_bufs);
>> > +
>> > +int venus_helper_alloc_dpb_bufs(struct venus_inst *inst)
>> > +{
>> > +	struct venus_core *core = inst->core;
>> > +	struct device *dev = core->dev;
>> > +	enum hfi_version ver = core->res->hfi_version;
>> > +	struct hfi_buffer_requirements bufreq;
>> > +	u32 buftype = inst->dpb_buftype;
>> > +	unsigned int dpb_size = 0;
>> > +	struct intbuf *buf;
>> > +	unsigned int i;
>> > +	u32 count;
>> > +	int ret;
>> > +
>> > +	/* no need to allocate dpb buffers */
>> > +	if (!inst->dpb_fmt)
>> > +		return 0;
>> > +
>> > +	if (inst->dpb_buftype == HFI_BUFFER_OUTPUT)
>> > +		dpb_size = inst->output_buf_size;
>> > +	else if (inst->dpb_buftype == HFI_BUFFER_OUTPUT2)
>> > +		dpb_size = inst->output2_buf_size;
>> > +
>> > +	if (!dpb_size)
>> > +		return 0;
>> > +
>> > +	ret = venus_helper_get_bufreq(inst, buftype, &bufreq);
>> > +	if (ret)
>> > +		return ret;
>> > +
>> > +	count = HFI_BUFREQ_COUNT_MIN(&bufreq, ver);
>> > +
>> > +	for (i = 0; i < count; i++) {
>> > +		buf = kzalloc(sizeof(*buf), GFP_KERNEL);
>> > +		if (!buf) {
>> > +			ret = -ENOMEM;
>> > +			goto fail;
>> > +		}
>> > +
>> > +		buf->type = buftype;
>> > +		buf->size = dpb_size;
>> > +		buf->attrs = DMA_ATTR_WRITE_COMBINE |
>> > +			     DMA_ATTR_NO_KERNEL_MAPPING;
>> > +		buf->va = dma_alloc_attrs(dev, buf->size, &buf-
>> > >da, GFP_KERNEL,
>> > +					  buf->attrs);
>> > +		if (!buf->va) {
>> > +			kfree(buf);
>> > +			ret = -ENOMEM;
>> > +			goto fail;
>> > +		}
>> > +
>> > +		list_add_tail(&buf->list, &inst->dpbbufs);
>> > +	}
>> > +
>> > +	return 0;
>> > +
>> > +fail:
>> > +	venus_helper_free_dpb_bufs(inst);
>> > +	return ret;
>> > +}
>> > +EXPORT_SYMBOL_GPL(venus_helper_alloc_dpb_bufs);
>> > +
>> >  static int intbufs_set_buffer(struct venus_inst *inst, u32 type)
>> >  {
>> >  	struct venus_core *core = inst->core;
>> > @@ -342,7 +448,10 @@ session_process_buf(struct venus_inst *inst,
>> > struct vb2_v4l2_buffer *vbuf)
>> >  		if (vbuf->flags & V4L2_BUF_FLAG_LAST ||
>> > !fdata.filled_len)
>> >  			fdata.flags |= HFI_BUFFERFLAG_EOS;
>> >  	} else if (type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE) {
>> > -		fdata.buffer_type = HFI_BUFFER_OUTPUT;
>> > +		if (inst->session_type == VIDC_SESSION_TYPE_ENC)
>> > +			fdata.buffer_type = HFI_BUFFER_OUTPUT;
>> > +		else
>> > +			fdata.buffer_type = inst->opb_buftype;
>> >  		fdata.filled_len = 0;
>> >  		fdata.offset = 0;
>> >  	}
>> > @@ -675,6 +784,27 @@ int venus_helper_set_color_format(struct
>> > venus_inst *inst, u32 pixfmt)
>> >  }
>> >  EXPORT_SYMBOL_GPL(venus_helper_set_color_format);
>> >
>> > +int venus_helper_set_multistream(struct venus_inst *inst, bool
>> > out_en,
>> > +				 bool out2_en)
>> > +{
>> > +	struct hfi_multi_stream multi = {0};
>> > +	u32 ptype = HFI_PROPERTY_PARAM_VDEC_MULTI_STREAM;
>> > +	int ret;
>> > +
>> > +	multi.buffer_type = HFI_BUFFER_OUTPUT;
>> > +	multi.enable = out_en;
>> > +
>> > +	ret = hfi_session_set_property(inst, ptype, &multi);
>> > +	if (ret)
>> > +		return ret;
>> > +
>> > +	multi.buffer_type = HFI_BUFFER_OUTPUT2;
>> > +	multi.enable = out2_en;
>> > +
>> > +	return hfi_session_set_property(inst, ptype, &multi);
>> > +}
>> > +EXPORT_SYMBOL_GPL(venus_helper_set_multistream);
>> > +
>> >  int venus_helper_set_dyn_bufmode(struct venus_inst *inst)
>> >  {
>> >  	u32 ptype = HFI_PROPERTY_PARAM_BUFFER_ALLOC_MODE;
>> > @@ -822,9 +952,10 @@ EXPORT_SYMBOL_GPL(venus_helper_vb2_buf_init);
>> >  int venus_helper_vb2_buf_prepare(struct vb2_buffer *vb)
>> >  {
>> >  	struct venus_inst *inst = vb2_get_drv_priv(vb->vb2_queue);
>> > +	unsigned int out_buf_size =
>> > venus_helper_get_opb_size(inst);
>> >
>> >  	if (vb->type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE &&
>> > -	    vb2_plane_size(vb, 0) < inst->output_buf_size)
>> > +	    vb2_plane_size(vb, 0) < out_buf_size)
>> >  		return -EINVAL;
>> >  	if (vb->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE &&
>> >  	    vb2_plane_size(vb, 0) < inst->input_buf_size)
>> > @@ -894,6 +1025,8 @@ void venus_helper_vb2_stop_streaming(struct
>> > vb2_queue *q)
>> >  		if (ret)
>> >  			hfi_session_abort(inst);
>> >
>> > +		venus_helper_free_dpb_bufs(inst);
>> > +
>> >  		load_scale_clocks(core);
>> >  		INIT_LIST_HEAD(&inst->registeredbufs);
>> >  	}
>> > @@ -932,8 +1065,14 @@ int venus_helper_vb2_start_streaming(struct
>> > venus_inst *inst)
>> >  	if (ret)
>> >  		goto err_unload_res;
>> >
>> > +	ret = venus_helper_queue_dpb_bufs(inst);
>> > +	if (ret)
>> > +		goto err_session_stop;
>> > +
>> >  	return 0;
>> >
>> > +err_session_stop:
>> > +	hfi_session_stop(inst);
>> >  err_unload_res:
>> >  	hfi_session_unload_res(inst);
>> >  err_unreg_bufs:
>> > @@ -987,6 +1126,67 @@ void venus_helper_init_instance(struct
>> > venus_inst
>> > *inst)
>> >  }
>> >  EXPORT_SYMBOL_GPL(venus_helper_init_instance);
>> >
>> > +static bool find_fmt_from_caps(struct venus_caps *caps, u32
>> > buftype,
>> > u32 fmt)
>> > +{
>> > +	unsigned int i;
>> > +
>> > +	for (i = 0; i < caps->num_fmts; i++) {
>> > +		if (caps->fmts[i].buftype == buftype &&
>> > +		    caps->fmts[i].fmt == fmt)
>> > +			return true;
>> > +	}
>> > +
>> > +	return false;
>> > +}
>> > +
>> > +int venus_helper_get_out_fmts(struct venus_inst *inst, u32
>> > v4l2_fmt,
>> > +			      u32 *out_fmt, u32 *out2_fmt, bool
>> > ubwc)
>> > +{
>> > +	struct venus_core *core = inst->core;
>> > +	struct venus_caps *caps;
>> > +	u32 ubwc_fmt, fmt = to_hfi_raw_fmt(v4l2_fmt);
>> > +	bool found, found_ubwc;
>> > +
>> > +	*out_fmt = *out2_fmt = 0;
>> > +
>> > +	if (!fmt)
>> > +		return -EINVAL;
>> > +
>> > +	caps = venus_caps_by_codec(core, inst->hfi_codec,
>> > inst->session_type);
>> > +	if (!caps)
>> > +		return -EINVAL;
>> > +
>> > +	if (ubwc) {
>> > +		ubwc_fmt = fmt | HFI_COLOR_FORMAT_UBWC_BASE;
>> > +		found_ubwc = find_fmt_from_caps(caps,
>> > HFI_BUFFER_OUTPUT,
>> > +						ubwc_fmt);
>> > +		found = find_fmt_from_caps(caps,
>> > HFI_BUFFER_OUTPUT2, fmt);
>> > +
>> > +		if (found_ubwc && found) {
>> > +			*out_fmt = ubwc_fmt;
>> > +			*out2_fmt = fmt;
>> > +			return 0;
>> > +		}
>> > +	}
>> > +
>> > +	found = find_fmt_from_caps(caps, HFI_BUFFER_OUTPUT, fmt);
>> > +	if (found) {
>> > +		*out_fmt = fmt;
>> > +		*out2_fmt = 0;
>> > +		return 0;
>> > +	}
>> > +
>> > +	found = find_fmt_from_caps(caps, HFI_BUFFER_OUTPUT2, fmt);
>> > +	if (found) {
>> > +		*out_fmt = 0;
>> > +		*out2_fmt = fmt;
>> > +		return 0;
>> > +	}
>> > +
>> > +	return -EINVAL;
>> > +}
>> > +EXPORT_SYMBOL_GPL(venus_helper_get_out_fmts);
>> > +
>> >  int venus_helper_power_enable(struct venus_core *core, u32
>> > session_type,
>> >  			      bool enable)
>> >  {
>> > diff --git a/drivers/media/platform/qcom/venus/helpers.h
>> > b/drivers/media/platform/qcom/venus/helpers.h
>> > index 92b167a47166..2475f284f396 100644
>> > --- a/drivers/media/platform/qcom/venus/helpers.h
>> > +++ b/drivers/media/platform/qcom/venus/helpers.h
>> > @@ -50,10 +50,16 @@ int venus_helper_set_raw_format(struct
>> > venus_inst
>> > *inst, u32 hfi_format,
>> >  int venus_helper_set_color_format(struct venus_inst *inst, u32
>> > fmt);
>> >  int venus_helper_set_dyn_bufmode(struct venus_inst *inst);
>> >  int venus_helper_set_bufsize(struct venus_inst *inst, u32 bufsize,
>> > u32 buftype);
>> > +int venus_helper_set_multistream(struct venus_inst *inst, bool
>> > out_en,
>> > +				 bool out2_en);
>> >  unsigned int venus_helper_get_opb_size(struct venus_inst *inst);
>> >  void venus_helper_acquire_buf_ref(struct vb2_v4l2_buffer *vbuf);
>> >  void venus_helper_release_buf_ref(struct venus_inst *inst,
>> > unsigned
>> > int idx);
>> >  void venus_helper_init_instance(struct venus_inst *inst);
>> > +int venus_helper_get_out_fmts(struct venus_inst *inst, u32 fmt,
>> > u32
>> > *out_fmt,
>> > +			      u32 *out2_fmt, bool ubwc);
>> > +int venus_helper_alloc_dpb_bufs(struct venus_inst *inst);
>> > +int venus_helper_free_dpb_bufs(struct venus_inst *inst);
>> >  int venus_helper_power_enable(struct venus_core *core, u32
>> > session_type,
>> >  			      bool enable);
>> >  #endif
>> > diff --git a/drivers/media/platform/qcom/venus/vdec.c
>> > b/drivers/media/platform/qcom/venus/vdec.c
>> > index 589fc13b84bc..7deee104ac56 100644
>> > --- a/drivers/media/platform/qcom/venus/vdec.c
>> > +++ b/drivers/media/platform/qcom/venus/vdec.c
>> > @@ -532,10 +532,16 @@ static int vdec_set_properties(struct
>> > venus_inst
>> > *inst)
>> >  	return 0;
>> >  }
>> >
>> > +#define is_ubwc_fmt(fmt) (!!((fmt) & HFI_COLOR_FORMAT_UBWC_BASE))
>> > +
>> >  static int vdec_output_conf(struct venus_inst *inst)
>> >  {
>> >  	struct venus_core *core = inst->core;
>> >  	struct hfi_enable en = { .enable = 1 };
>> > +	u32 width = inst->out_width;
>> > +	u32 height = inst->out_height;
>> > +	u32 out_fmt, out2_fmt;
>> > +	bool ubwc = false;
>> >  	u32 ptype;
>> >  	int ret;
>> >
>> > @@ -554,6 +560,78 @@ static int vdec_output_conf(struct venus_inst
>> > *inst)
>> >  			return ret;
>> >  	}
>> >
>> > +	if (width > 1920 && height > ALIGN(1080, 32))
>> > +		ubwc = true;
>> > +
>> > +	if (IS_V4(core))
>> > +		ubwc = true;
>> > +
>> > +	ret = venus_helper_get_out_fmts(inst, inst->fmt_cap-
>> > >pixfmt,
>> > &out_fmt,
>> > +					&out2_fmt, ubwc);
>> > +	if (ret)
>> > +		return ret;
>> > +
>> > +	inst->output_buf_size =
>> > +			venus_helper_get_framesz_raw(out_fmt,
>> > width, height);
>> > +	inst->output2_buf_size =
>> > +			venus_helper_get_framesz_raw(out2_fmt,
>> > width, height);
>> > +
>> > +	if (is_ubwc_fmt(out_fmt)) {
>> > +		inst->opb_buftype = HFI_BUFFER_OUTPUT2;
>> > +		inst->opb_fmt = out2_fmt;
>> > +		inst->dpb_buftype = HFI_BUFFER_OUTPUT;
>> > +		inst->dpb_fmt = out_fmt;
>> > +	} else if (is_ubwc_fmt(out2_fmt)) {
>> > +		inst->opb_buftype = HFI_BUFFER_OUTPUT;
>> > +		inst->opb_fmt = out_fmt;
>> > +		inst->dpb_buftype = HFI_BUFFER_OUTPUT2;
>> > +		inst->dpb_fmt = out2_fmt;
>> > +	} else {
>> > +		inst->opb_buftype = HFI_BUFFER_OUTPUT;
>> > +		inst->opb_fmt = out_fmt;
>> > +		inst->dpb_buftype = 0;
>> > +		inst->dpb_fmt = 0;
>> > +	}
>> > +
>> > +	ret = venus_helper_set_raw_format(inst, inst->opb_fmt,
>> > +					  inst->opb_buftype);
>> > +	if (ret)
>> > +		return ret;
>> > +
>> > +	if (inst->dpb_fmt) {
>> > +		ret = venus_helper_set_multistream(inst, false,
>> > true);
>> > +		if (ret)
>> > +			return ret;
>> > +
>> > +		ret = venus_helper_set_raw_format(inst, inst-
>> > >dpb_fmt,
>> > +						  inst-
>> > >dpb_buftype);
>> > +		if (ret)
>> > +			return ret;
>> > +
>> > +		ret = venus_helper_set_output_resolution(inst,
>> > width, height,
>> > +							 HFI_BUFFE
>> > R_OUTPUT2);
>> > +		if (ret)
>> > +			return ret;
>> > +	}
>> > +
>> > +	if (IS_V3(core) || IS_V4(core)) {
>> > +		if (inst->output2_buf_size) {
>> > +			ret = venus_helper_set_bufsize(inst,
>> > +						       inst-
>> > >output2_buf_size,
>> > +						       HFI_BUFFER_
>> > OUTPUT2);
>> > +			if (ret)
>> > +				return ret;
>> > +		}
>> > +
>> > +		if (inst->output_buf_size) {
>> > +			ret = venus_helper_set_bufsize(inst,
>> > +						       inst-
>> > >output_buf_size,
>> > +						       HFI_BUFFER_
>> > OUTPUT);
>> > +			if (ret)
>> > +				return ret;
>> > +		}
>> > +	}
>> > +
>> >  	ret = venus_helper_set_dyn_bufmode(inst);
>> >  	if (ret)
>> >  		return ret;
>> > @@ -624,6 +702,8 @@ static int vdec_queue_setup(struct vb2_queue
>> > *q,
>> >  	int ret = 0;
>> >
>> >  	if (*num_planes) {
>> > +		unsigned int output_buf_size =
>> > venus_helper_get_opb_size(inst);
>> > +
>> >  		if (q->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
>> > &&
>> >  		    *num_planes != inst->fmt_out->num_planes)
>> >  			return -EINVAL;
>> > @@ -637,7 +717,7 @@ static int vdec_queue_setup(struct vb2_queue
>> > *q,
>> >  			return -EINVAL;
>> >
>> >  		if (q->type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
>> > &&
>> > -		    sizes[0] < inst->output_buf_size)
>> > +		    sizes[0] < output_buf_size)
>> >  			return -EINVAL;
>> >
>> >  		return 0;
>> > @@ -746,6 +826,10 @@ static int vdec_start_streaming(struct
>> > vb2_queue
>> > *q, unsigned int count)
>> >  	if (ret)
>> >  		goto deinit_sess;
>> >
>> > +	ret = venus_helper_alloc_dpb_bufs(inst);
>> > +	if (ret)
>> > +		goto deinit_sess;
>> > +
>> >  	ret = venus_helper_vb2_start_streaming(inst);
>> >  	if (ret)
>> >  		goto deinit_sess;
>> > @@ -797,9 +881,11 @@ static void vdec_buf_done(struct venus_inst
>> > *inst, unsigned int buf_type,
>> >  	vbuf->field = V4L2_FIELD_NONE;
>> >
>> >  	if (type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE) {
>> > +		unsigned int opb_sz =
>> > venus_helper_get_opb_size(inst);
>> > +
>> >  		vb = &vbuf->vb2_buf;
>> >  		vb->planes[0].bytesused =
>> > -			max_t(unsigned int, inst->output_buf_size,
>> > bytesused);
>> > +			max_t(unsigned int, opb_sz, bytesused);
>> >  		vb->planes[0].data_offset = data_offset;
>> >  		vb->timestamp = timestamp_us * NSEC_PER_USEC;
>> >  		vbuf->sequence = inst->sequence_cap++;
>> > @@ -945,6 +1031,7 @@ static int vdec_open(struct file *file)
>> >  	if (!inst)
>> >  		return -ENOMEM;
>> >
>> > +	INIT_LIST_HEAD(&inst->dpbbufs);
>> >  	INIT_LIST_HEAD(&inst->registeredbufs);
>> >  	INIT_LIST_HEAD(&inst->internalbufs);
>> >  	INIT_LIST_HEAD(&inst->list);
>> > diff --git a/drivers/media/platform/qcom/venus/venc.c
>> > b/drivers/media/platform/qcom/venus/venc.c
>> > index 54f253b98b24..a703bce78abc 100644
>> > --- a/drivers/media/platform/qcom/venus/venc.c
>> > +++ b/drivers/media/platform/qcom/venus/venc.c
>> > @@ -1084,6 +1084,7 @@ static int venc_open(struct file *file)
>> >  	if (!inst)
>> >  		return -ENOMEM;
>> >
>> > +	INIT_LIST_HEAD(&inst->dpbbufs);
>> >  	INIT_LIST_HEAD(&inst->registeredbufs);
>> >  	INIT_LIST_HEAD(&inst->internalbufs);
>> >  	INIT_LIST_HEAD(&inst->list);
>> 
>> The dpb buffers queued to hardware will be returned back to host
>> either
>> during flush
>> or when the session is stopped. Host should not send these buffers
>> to
>> client.
>> vdec_buf_done should be handling in a way to drop dpb buffers from
>> sending to client.
> 
> Are you sure ? In V4L2 the CODEC is only ever flushed or stopped
> through userspace actions (STREAMOFF). In which case, userspace expects
> all buffers to be dequeued by the driver. Userspace will requeue them
> ignoring their content.

DPB buffers, which i mentioned earlier, are managed 
(allocated/queued/freed)
internally in video driver. Client is nowhere aware of it and does not 
expects
the same to be dequeued/requeue.

>> 
>> Thanks,
>> Vikash