RE: [EXT] Re: [PATCH v13 06/13] media: amphion: add vpu v4l2 m2m support

quoted

+
+int vpu_v4l2_open(struct file *file, struct vpu_inst *inst)
+{
+     struct vpu_dev *vpu = video_drvdata(file);
+     struct vpu_func *func;
+     int ret = 0;
+
+     WARN_ON(!file || !inst || !inst->ops);
+
+     if (inst->type == VPU_CORE_TYPE_ENC)
+             func = &vpu->encoder;
+     else
+             func = &vpu->decoder;
+
+     atomic_set(&inst->ref_count, 0);
+     vpu_inst_get(inst);
+     inst->vpu = vpu;
+     inst->core = vpu_request_core(vpu, inst->type);
+     if (inst->core)
+             inst->dev = get_device(inst->core->dev);
+     mutex_init(&inst->lock);
+     INIT_LIST_HEAD(&inst->cmd_q);
+     inst->id = VPU_INST_NULL_ID;
+     inst->release = vpu_v4l2_release;
+     inst->pid = current->pid;
+     inst->tgid = current->tgid;
+     inst->min_buffer_cap = 2;
+     inst->min_buffer_out = 2;

Assuming this means the minimum number of buffers needed, why is
min_buffers_needed set to 1 when initializing the vb2_queue structs?

In my opinion, the min_buffers_needed determine when vb2_start_streaming will be called,
Like the following code:
if (q->queued_count >= q->min_buffers_needed) {
        ... ...
        ret = vb2_start_streaming(q);
        ... ...
}
I hope driver starts a vpu instance when 1 frame is queued, so I set the min_buffers_needed to 1.
And the min_buffer_cap means the minimum vb2 buffer count, and it will changed according to the stream,
I just set default value to 2, it will be changed after vpu parsed the stream info.

quoted

+     v4l2_fh_init(&inst->fh, func->vfd);
+     v4l2_fh_add(&inst->fh);
+
+     ret = call_vop(inst, ctrl_init);
+     if (ret)
+             goto error;
+
+     inst->fh.m2m_ctx = v4l2_m2m_ctx_init(func->m2m_dev,
+                                     inst, vpu_m2m_queue_init);
+     if (IS_ERR(inst->fh.m2m_ctx)) {
+             dev_err(vpu->dev, "v4l2_m2m_ctx_init fail\n");
+             ret = PTR_ERR(func->m2m_dev);
+             goto error;
+     }
+
+     inst->fh.ctrl_handler = &inst->ctrl_handler;
+     file->private_data = &inst->fh;
+     inst->state = VPU_CODEC_STATE_DEINIT;
+     inst->workqueue = alloc_workqueue("vpu_inst", WQ_UNBOUND |

WQ_MEM_RECLAIM, 1);

quoted

+     if (inst->workqueue) {
+             INIT_WORK(&inst->msg_work, vpu_inst_run_work);
+             ret = kfifo_init(&inst->msg_fifo,
+                             inst->msg_buffer,
+

roundup_pow_of_two(sizeof(inst->msg_buffer)));

quoted

+             if (ret) {
+                     destroy_workqueue(inst->workqueue);
+                     inst->workqueue = NULL;
+             }
+     }
+     vpu_trace(vpu->dev, "tgid = %d, pid = %d, type = %s, inst = %p\n",
+                     inst->tgid, inst->pid,

vpu_core_type_desc(inst->type), inst);

quoted

+
+     return 0;
+error:
+     vpu_inst_put(inst);
+     return ret;
+}
+

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel