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References: <20190117162008.25217-1-stanimir.varbanov@linaro.org> <20190117162008.25217-11-stanimir.varbanov@linaro.org>
In-Reply-To: <20190117162008.25217-11-stanimir.varbanov@linaro.org>
From:   Alexandre Courbot <acourbot@chromium.org>
Date:   Thu, 24 Jan 2019 17:44:20 +0900
Message-ID: <CAPBb6MWMOBRrRYbbVjvm=075o_Sbmh3jVj3PNZ2dmMXu6UOzmw@mail.gmail.com>
Subject: Re: [PATCH 10/10] venus: dec: make decoder compliant with stateful
 codec API
To:     Stanimir Varbanov <stanimir.varbanov@linaro.org>
Cc:     Linux Media Mailing List <linux-media@vger.kernel.org>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Hans Verkuil <hverkuil@xs4all.nl>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-arm-msm@vger.kernel.org,
        Vikash Garodia <vgarodia@codeaurora.org>,
        Tomasz Figa <tfiga@chromium.org>,
        Malathi Gottam <mgottam@codeaurora.org>
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Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Fri, Jan 18, 2019 at 1:21 AM Stanimir Varbanov
<stanimir.varbanov@linaro.org> 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@linaro.org>
> ---
>  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?