CMD_BUFFER_SIZE
memset(priv->cmd_buffer, 0, CMD_BUFFER_SIZE);
ret = hid_hw_output_report(priv->hdev, priv->cmd_buffer, CMD_BUFFER_SIZE);
priv->cmd_buffer = devm_kmalloc(&hdev->dev, CMD_BUFFER_SIZE, GFP_KERNEL);
memcpy(priv->cmd_buffer, data, min(CMD_BUFFER_SIZE, size));
iommu->cmd_buf = iommu_memremap(paddr, CMD_BUFFER_SIZE);
iommu->cmd_buf = iommu_alloc_pages_sz(GFP_KERNEL, CMD_BUFFER_SIZE);
tail = (tail + sizeof(*cmd)) % CMD_BUFFER_SIZE;
next_tail = (iommu->cmd_buf_tail + sizeof(*cmd)) % CMD_BUFFER_SIZE;
left = (iommu->cmd_buf_head - next_tail) % CMD_BUFFER_SIZE;
b = kmalloc(CMD_BUFFER_SIZE + PCTV_ANSWER_LEN, GFP_KERNEL);
rx = b + CMD_BUFFER_SIZE;