| .. SPDX-License-Identifier: GPL-2.0 | |
| .. include:: <isonum.txt> | |
| ASPEED video driver | |
| =================== | |
| ASPEED Video Engine found on AST2400/2500/2600 SoC supports high performance | |
| video compressions with a wide range of video quality and compression ratio | |
| options. The adopted compressing algorithm is a modified JPEG algorithm. | |
| There are 2 types of compressions in this IP. | |
| * JPEG JFIF standard mode: for single frame and management compression | |
| * ASPEED proprietary mode: for multi-frame and differential compression. | |
| Support 2-pass (high quality) video compression scheme (Patent pending by | |
| ASPEED). Provide visually lossless video compression quality or to reduce | |
| the network average loading under intranet KVM applications. | |
| VIDIOC_S_FMT can be used to choose which format you want. V4L2_PIX_FMT_JPEG | |
| stands for JPEG JFIF standard mode; V4L2_PIX_FMT_AJPG stands for ASPEED | |
| proprietary mode. | |
| More details on the ASPEED video hardware operations can be found in | |
| *chapter 6.2.16 KVM Video Driver* of SDK_User_Guide which available on | |
| `github <https://github.com/AspeedTech-BMC/openbmc/releases/>`__. | |
| The ASPEED video driver implements the following driver-specific control: | |
| ``V4L2_CID_ASPEED_HQ_MODE`` | |
| --------------------------- | |
| Enable/Disable ASPEED's High quality mode. This is a private control | |
| that can be used to enable high quality for aspeed proprietary mode. | |
| .. flat-table:: | |
| :header-rows: 0 | |
| :stub-columns: 0 | |
| :widths: 1 4 | |
| * - ``(0)`` | |
| - ASPEED HQ mode is disabled. | |
| * - ``(1)`` | |
| - ASPEED HQ mode is enabled. | |
| ``V4L2_CID_ASPEED_HQ_JPEG_QUALITY`` | |
| ----------------------------------- | |
| Define the quality of ASPEED's High quality mode. This is a private control | |
| that can be used to decide compression quality if High quality mode enabled | |
| . Higher the value, better the quality and bigger the size. | |
| .. flat-table:: | |
| :header-rows: 0 | |
| :stub-columns: 0 | |
| :widths: 1 4 | |
| * - ``(1)`` | |
| - minimum | |
| * - ``(12)`` | |
| - maximum | |
| * - ``(1)`` | |
| - step | |
| * - ``(1)`` | |
| - default | |
| **Copyright** |copy| 2022 ASPEED Technology Inc. |