Re: [PATCH 10/10] venus: dec: make decoder compliant with stateful codec API

From: Alexandre Courbot
Date: Thu Jan 24 2019 - 03:44:37 EST


On Fri, Jan 18, 2019 at 1:21 AM Stanimir Varbanov
<stanimir.varbanov@xxxxxxxxxx> wrote:
>
> This refactored code for start/stop streaming vb2 operations and

s/refactored/refactors?

> adds a state machine handling similar to the one in stateful codec
> API documentation. One major change is that now the HFI session is
> started on STREAMON(OUTPUT) and stopped on REQBUF(OUTPUT,count=0),
> during that time streamoff(cap,out) just flush buffers but doesn't

streamoff(cap,out) should probably be in capitals for consistency.

> stop the session. The other major change is that now the capture
> and output queues are completely separated.
>
> Signed-off-by: Stanimir Varbanov <stanimir.varbanov@xxxxxxxxxx>
> ---
> drivers/media/platform/qcom/venus/core.h | 20 +-
> drivers/media/platform/qcom/venus/helpers.c | 23 +-
> drivers/media/platform/qcom/venus/helpers.h | 5 +
> drivers/media/platform/qcom/venus/vdec.c | 449 ++++++++++++++++----
> 4 files changed, 389 insertions(+), 108 deletions(-)
>
> diff --git a/drivers/media/platform/qcom/venus/core.h b/drivers/media/platform/qcom/venus/core.h
> index 79c7e816c706..5a133c203455 100644
> --- a/drivers/media/platform/qcom/venus/core.h
> +++ b/drivers/media/platform/qcom/venus/core.h
> @@ -218,6 +218,15 @@ struct venus_buffer {
>
> #define to_venus_buffer(ptr) container_of(ptr, struct venus_buffer, vb)
>
> +#define DEC_STATE_UNINIT 0

Not sure about "uninit", DEC_STATE_DEINIT may be more explicit here?

> +#define DEC_STATE_INIT 1
> +#define DEC_STATE_CAPTURE_SETUP 2
> +#define DEC_STATE_STOPPED 3
> +#define DEC_STATE_SEEK 4
> +#define DEC_STATE_DRAIN 5
> +#define DEC_STATE_DECODING 6
> +#define DEC_STATE_DRC 7

How about defining these as an enum, for better type safety? I'd also
prefix with VENUS_ to avoid possible (if unlikely) name collisions.

> +
> /**
> * struct venus_inst - holds per instance paramerters
> *
> @@ -241,6 +250,10 @@ struct venus_buffer {
> * @colorspace: current color space
> * @quantization: current quantization
> * @xfer_func: current xfer function
> + * @codec_state: current codec API state (see DEC/ENC_STATE_)
> + * @reconf_wait: wait queue for resolution change event
> + * @ten_bits: does new stream is 10bits depth

"is new stream 10 bits deep" maybe?

> + * @buf_count: used to count number number of buffers (reqbuf(0))

"number" written twice here.

> * @fps: holds current FPS
> * @timeperframe: holds current time per frame structure
> * @fmt_out: a reference to output format structure
> @@ -255,8 +268,6 @@ struct venus_buffer {
> * @opb_buftype: output picture buffer type
> * @opb_fmt: output picture buffer raw format
> * @reconfig: a flag raised by decoder when the stream resolution changed
> - * @reconfig_width: holds the new width
> - * @reconfig_height: holds the new height
> * @hfi_codec: current codec for this instance in HFI space
> * @sequence_cap: a sequence counter for capture queue
> * @sequence_out: a sequence counter for output queue
> @@ -296,6 +307,9 @@ struct venus_inst {
> u8 ycbcr_enc;
> u8 quantization;
> u8 xfer_func;
> + unsigned int codec_state;

As mentioned above, with an enum the type of this member would make it
obvious which values it can accept.

> + wait_queue_head_t reconf_wait;
> + int buf_count;
> u64 fps;
> struct v4l2_fract timeperframe;
> const struct venus_format *fmt_out;
> @@ -310,8 +324,6 @@ struct venus_inst {
> u32 opb_buftype;
> u32 opb_fmt;
> bool reconfig;
> - u32 reconfig_width;
> - u32 reconfig_height;
> u32 hfi_codec;
> u32 sequence_cap;
> u32 sequence_out;
> diff --git a/drivers/media/platform/qcom/venus/helpers.c b/drivers/media/platform/qcom/venus/helpers.c
> index 637ce7b82d94..25d8cceccae4 100644
> --- a/drivers/media/platform/qcom/venus/helpers.c
> +++ b/drivers/media/platform/qcom/venus/helpers.c
> @@ -1030,16 +1030,15 @@ void venus_helper_vb2_buf_queue(struct vb2_buffer *vb)
>
> v4l2_m2m_buf_queue(m2m_ctx, vbuf);
>
> - if (!(inst->streamon_out & inst->streamon_cap))
> - goto unlock;
> -
> - ret = is_buf_refed(inst, vbuf);
> - if (ret)
> - goto unlock;
> + if (IS_OUT(vb->vb2_queue, inst) || IS_CAP(vb->vb2_queue, inst)) {
> + ret = is_buf_refed(inst, vbuf);
> + if (ret)
> + goto unlock;
>
> - ret = session_process_buf(inst, vbuf);
> - if (ret)
> - return_buf_error(inst, vbuf);
> + ret = session_process_buf(inst, vbuf);
> + if (ret)
> + return_buf_error(inst, vbuf);
> + }
>
> unlock:
> mutex_unlock(&inst->lock);
> @@ -1155,14 +1154,8 @@ 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:
> diff --git a/drivers/media/platform/qcom/venus/helpers.h b/drivers/media/platform/qcom/venus/helpers.h
> index 2ec1c1a8b416..3b46139b5ee1 100644
> --- a/drivers/media/platform/qcom/venus/helpers.h
> +++ b/drivers/media/platform/qcom/venus/helpers.h
> @@ -17,6 +17,11 @@
>
> #include <media/videobuf2-v4l2.h>
>
> +#define IS_OUT(q, inst) (inst->streamon_out && \
> + q->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE)
> +#define IS_CAP(q, inst) (inst->streamon_cap && \
> + q->type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE)

These macro names are pretty generic and we are at risk of a name
collision in the future. Also the name conveys the idea that the macro
will check for the buffer type only ; yet IIUC we also check that the
corresponding queue is streaming? Maybe something like
VENUS_BUF_OUT_READY() would be more meaningful.

> +
> struct venus_inst;
> struct venus_core;
>
> diff --git a/drivers/media/platform/qcom/venus/vdec.c b/drivers/media/platform/qcom/venus/vdec.c
> index 7a9370df7515..306e0f7d3337 100644
> --- a/drivers/media/platform/qcom/venus/vdec.c
> +++ b/drivers/media/platform/qcom/venus/vdec.c
> @@ -201,28 +201,18 @@ static int vdec_g_fmt(struct file *file, void *fh, struct v4l2_format *f)
> struct venus_inst *inst = to_inst(file);
> const struct venus_format *fmt = NULL;
> struct v4l2_pix_format_mplane *pixmp = &f->fmt.pix_mp;
> + int ret;
>
> if (f->type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE)
> fmt = inst->fmt_cap;
> else if (f->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE)
> fmt = inst->fmt_out;
>
> - if (inst->reconfig) {
> - struct v4l2_format format = {};
> -
> - inst->out_width = inst->reconfig_width;
> - inst->out_height = inst->reconfig_height;
> - inst->reconfig = false;
> -
> - format.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
> - format.fmt.pix_mp.pixelformat = inst->fmt_cap->pixfmt;
> - format.fmt.pix_mp.width = inst->out_width;
> - format.fmt.pix_mp.height = inst->out_height;
> -
> - vdec_try_fmt_common(inst, &format);
> -
> - inst->width = format.fmt.pix_mp.width;
> - inst->height = format.fmt.pix_mp.height;
> + if (f->type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE) {
> + ret = wait_event_timeout(inst->reconf_wait, inst->reconfig,
> + msecs_to_jiffies(100));
> + if (!ret)
> + return -EINVAL;

inst->reconfig is only true during the time between a reconfigure
event and the start of the CAPTURE queue. This looks like G_FMT on the
CAPTURE queue will only be successful during this very short amount of
time. Is my understanding correct? I wonder whether I am missing
something here because the Chromium tests are all passing. But if this
is correct, then this looks very restrictive. For instance, one would
not be able to do VIDIOC_G_FMT twice in a row.

> }
>
> pixmp->pixelformat = fmt->pixfmt;
> @@ -457,6 +447,10 @@ vdec_try_decoder_cmd(struct file *file, void *fh, struct v4l2_decoder_cmd *cmd)
> if (cmd->flags & V4L2_DEC_CMD_STOP_TO_BLACK)
> return -EINVAL;
> break;
> + case V4L2_DEC_CMD_START:
> + if (cmd->flags & V4L2_DEC_CMD_START_MUTE_AUDIO)
> + return -EINVAL;
> + break;
> default:
> return -EINVAL;
> }
> @@ -477,18 +471,23 @@ vdec_decoder_cmd(struct file *file, void *fh, struct v4l2_decoder_cmd *cmd)
>
> mutex_lock(&inst->lock);
>
> - /*
> - * Implement V4L2_DEC_CMD_STOP by enqueue an empty buffer on decoder
> - * input to signal EOS.
> - */
> - if (!(inst->streamon_out & inst->streamon_cap))
> - goto unlock;
> + if (cmd->cmd == V4L2_DEC_CMD_STOP) {
> + /*
> + * Implement V4L2_DEC_CMD_STOP by enqueue an empty buffer on
> + * decoder input to signal EOS.
> + */
> + if (!(inst->streamon_out & inst->streamon_cap))
> + goto unlock;
>
> - fdata.buffer_type = HFI_BUFFER_INPUT;
> - fdata.flags |= HFI_BUFFERFLAG_EOS;
> - fdata.device_addr = 0xdeadbeef;
> + fdata.buffer_type = HFI_BUFFER_INPUT;
> + fdata.flags |= HFI_BUFFERFLAG_EOS;
> + fdata.device_addr = 0xdeadb000;
>
> - ret = hfi_session_process_buf(inst, &fdata);
> + ret = hfi_session_process_buf(inst, &fdata);
> +
> + if (!ret && inst->codec_state == DEC_STATE_DECODING)
> + inst->codec_state = DEC_STATE_DRAIN;
> + }
>
> unlock:
> mutex_unlock(&inst->lock);
> @@ -649,20 +648,18 @@ static int vdec_output_conf(struct venus_inst *inst)
> return 0;
> }
>
> -static int vdec_init_session(struct venus_inst *inst)
> +static int vdec_session_init(struct venus_inst *inst)
> {
> int ret;
>
> ret = hfi_session_init(inst, inst->fmt_out->pixfmt);
> - if (ret)
> + if (ret == -EINVAL)
> + return 0;

Why is -EINVAL ok? It would be helpful to have at least a comment to
explain this behavior.

> + else if (ret)
> return ret;
>
> - ret = venus_helper_set_input_resolution(inst, inst->out_width,
> - inst->out_height);
> - if (ret)
> - goto deinit;
> -
> - ret = venus_helper_set_color_format(inst, inst->fmt_cap->pixfmt);
> + ret = venus_helper_set_input_resolution(inst, frame_width_min(inst),
> + frame_height_min(inst));
> if (ret)
> goto deinit;
>
> @@ -681,26 +678,19 @@ static int vdec_num_buffers(struct venus_inst *inst, unsigned int *in_num,
>
> *in_num = *out_num = 0;
>
> - ret = vdec_init_session(inst);
> - if (ret)
> - return ret;
> -
> ret = venus_helper_get_bufreq(inst, HFI_BUFFER_INPUT, &bufreq);
> if (ret)
> - goto deinit;
> + return ret;
>
> *in_num = HFI_BUFREQ_COUNT_MIN(&bufreq, ver);
>
> ret = venus_helper_get_bufreq(inst, HFI_BUFFER_OUTPUT, &bufreq);
> if (ret)
> - goto deinit;
> + return ret;
>
> *out_num = HFI_BUFREQ_COUNT_MIN(&bufreq, ver);
>
> -deinit:
> - hfi_session_deinit(inst);
> -
> - return ret;
> + return 0;
> }
>
> static int vdec_queue_setup(struct vb2_queue *q,
> @@ -733,6 +723,10 @@ static int vdec_queue_setup(struct vb2_queue *q,
> return 0;
> }
>
> + ret = vdec_session_init(inst);
> + if (ret)
> + return ret;
> +
> ret = vdec_num_buffers(inst, &in_num, &out_num);
> if (ret)
> return ret;
> @@ -758,6 +752,11 @@ static int vdec_queue_setup(struct vb2_queue *q,
> inst->output_buf_size = sizes[0];
> *num_buffers = max(*num_buffers, out_num);
> inst->num_output_bufs = *num_buffers;
> +
> + mutex_lock(&inst->lock);
> + if (inst->codec_state == DEC_STATE_CAPTURE_SETUP)
> + inst->codec_state = DEC_STATE_STOPPED;
> + mutex_unlock(&inst->lock);
> break;
> default:
> ret = -EINVAL;
> @@ -794,80 +793,298 @@ static int vdec_verify_conf(struct venus_inst *inst)
> return 0;
> }
>
> -static int vdec_start_streaming(struct vb2_queue *q, unsigned int count)
> +static int vdec_start_capture(struct venus_inst *inst)
> {
> - struct venus_inst *inst = vb2_get_drv_priv(q);
> int ret;
>
> - mutex_lock(&inst->lock);
> + if (!inst->streamon_out)
> + return -EINVAL;
>
> - if (q->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE)
> - inst->streamon_out = 1;
> - else
> - inst->streamon_cap = 1;
> + if (inst->codec_state == DEC_STATE_DECODING) {
> + if (inst->reconfig)
> + goto reconfigure;
>
> - if (!(inst->streamon_out & inst->streamon_cap)) {
> - mutex_unlock(&inst->lock);
> + venus_helper_queue_dpb_bufs(inst);
> + venus_helper_process_initial_cap_bufs(inst);
> + inst->streamon_cap = 1;
> return 0;
> }
>
> - venus_helper_init_instance(inst);
> + if (inst->codec_state != DEC_STATE_STOPPED)
> + return -EINVAL;
>
> - inst->reconfig = false;
> - inst->sequence_cap = 0;
> - inst->sequence_out = 0;
> +reconfigure:
> + ret = hfi_session_flush(inst, HFI_FLUSH_OUTPUT);
> + if (ret)
> + return ret;
>
> - ret = vdec_init_session(inst);
> + ret = vdec_output_conf(inst);
> if (ret)
> - goto bufs_done;
> + return ret;
> +
> + ret = venus_helper_set_num_bufs(inst, inst->num_input_bufs,
> + VB2_MAX_FRAME, VB2_MAX_FRAME);
> + if (ret)
> + return ret;
> +
> + ret = venus_helper_intbufs_realloc(inst);
> + if (ret)
> + goto err;
> +
> + ret = venus_helper_alloc_dpb_bufs(inst);
> + if (ret)
> + goto err;
> +
> + ret = venus_helper_queue_dpb_bufs(inst);
> + if (ret)
> + goto free_dpb_bufs;
> +
> + ret = venus_helper_process_initial_cap_bufs(inst);
> + if (ret)
> + goto free_dpb_bufs;
> +
> + venus_helper_load_scale_clocks(inst->core);
> +
> + ret = hfi_session_continue(inst);
> + if (ret)
> + goto free_dpb_bufs;
> +
> + inst->codec_state = DEC_STATE_DECODING;
> +
> + inst->streamon_cap = 1;
> + inst->sequence_cap = 0;
> + inst->reconfig = false;
> +
> + return 0;
> +
> +free_dpb_bufs:
> + venus_helper_free_dpb_bufs(inst);
> +err:
> + return ret;
> +}
> +
> +static int vdec_start_output(struct venus_inst *inst)
> +{
> + int ret;
> +
> + if (inst->codec_state == DEC_STATE_SEEK) {
> + ret = venus_helper_process_initial_out_bufs(inst);
> + inst->codec_state = DEC_STATE_DECODING;
> + goto done;
> + }
> +
> + if (inst->codec_state == DEC_STATE_INIT ||
> + inst->codec_state == DEC_STATE_CAPTURE_SETUP) {
> + ret = venus_helper_process_initial_out_bufs(inst);
> + goto done;
> + }
> +
> + if (inst->codec_state != DEC_STATE_UNINIT)
> + return -EINVAL;
> +
> + venus_helper_init_instance(inst);
> + inst->sequence_out = 0;
> + inst->reconfig = false;
>
> ret = vdec_set_properties(inst);
> if (ret)
> - goto deinit_sess;
> + return ret;
>
> ret = vdec_output_conf(inst);
> if (ret)
> - goto deinit_sess;
> + return ret;
>
> ret = vdec_verify_conf(inst);
> if (ret)
> - goto deinit_sess;
> + return ret;
>
> ret = venus_helper_set_num_bufs(inst, inst->num_input_bufs,
> VB2_MAX_FRAME, VB2_MAX_FRAME);
> if (ret)
> - goto deinit_sess;
> + return ret;
>
> - ret = venus_helper_alloc_dpb_bufs(inst);
> + ret = venus_helper_vb2_start_streaming(inst);
> if (ret)
> - goto deinit_sess;
> + return ret;
>
> - ret = venus_helper_vb2_start_streaming(inst);
> + ret = venus_helper_process_initial_out_bufs(inst);
> if (ret)
> - goto deinit_sess;
> + return ret;
>
> - mutex_unlock(&inst->lock);
> + inst->codec_state = DEC_STATE_INIT;
> +
> +done:
> + inst->streamon_out = 1;
> + return ret;
> +}
> +
> +static int vdec_start_streaming(struct vb2_queue *q, unsigned int count)
> +{
> + struct venus_inst *inst = vb2_get_drv_priv(q);
> + int ret;
> +
> + mutex_lock(&inst->lock);
> +
> + if (q->type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE)
> + ret = vdec_start_capture(inst);
> + else
> + ret = vdec_start_output(inst);
>
> + if (ret)
> + goto error;
> +
> + mutex_unlock(&inst->lock);
> return 0;
>
> -deinit_sess:
> - hfi_session_deinit(inst);
> -bufs_done:
> +error:
> venus_helper_buffers_done(inst, VB2_BUF_STATE_QUEUED);
> + mutex_unlock(&inst->lock);
> + return ret;
> +}
> +
> +static void vdec_dst_buffers_done(struct venus_inst *inst,
> + enum vb2_buffer_state state)

This function is only called as follows:

vdec_dst_buffers_done(inst, VB2_BUF_STATE_ERROR);

Therefore the state argument does not seem particularly useful. Maybe
we can omit it and give this function a more specific name like
vdec_cancel_dst_buffers().

> +{
> + struct vb2_v4l2_buffer *buf;
> +
> + while ((buf = v4l2_m2m_dst_buf_remove(inst->m2m_ctx)))
> + v4l2_m2m_buf_done(buf, state);
> +}
> +
> +static int vdec_stop_capture(struct venus_inst *inst)
> +{
> + int ret = 0;
> +
> + switch (inst->codec_state) {
> + case DEC_STATE_DECODING:
> + ret = hfi_session_flush(inst, HFI_FLUSH_ALL);
> + vdec_dst_buffers_done(inst, VB2_BUF_STATE_ERROR);
> + inst->codec_state = DEC_STATE_STOPPED;
> + break;
> + case DEC_STATE_DRAIN:
> + vdec_dst_buffers_done(inst, VB2_BUF_STATE_ERROR);
> + inst->codec_state = DEC_STATE_STOPPED;
> + break;

You can simplify these two cases a bit:

case DEC_STATE_DECODING:
ret = hfi_session_flush(inst, HFI_FLUSH_ALL);
/* fallthrough */
case DEC_STATE_DRAIN:
vdec_dst_buffers_done(inst, VB2_BUF_STATE_ERROR);
inst->codec_state = DEC_STATE_STOPPED;
break;

> + case DEC_STATE_DRC:

Just caught this now, but what does "DRC" stand for?