Chapter 3 UFS State Diagram

第三章 UFS状态图解

Section 1 UFS Power State transition Diagram

第一节UFS电源状态转移图解

There are mainly 6 states for Power State transitions in UFS, which are Power-On mode, Active mode, Idle mode, Sleep mode, Deep-Sleep mode, and Power-Down mode. Each mode is related to Power supply status together with physical line status.

UFS主要有六种电源状态转移的状态，它们还上电模式，活动模式，空闲模式，睡眠模式，深度睡眠模式以及下电模式。每一个模式都和电源供应以及物理线状态有关。

Power-On and Power-Down mode are simple, which represent the power supply on and off separately. Power supply here means VCC for NAND Flash and VCCQ（or VCCQ2）for UFS controller. Active mode is the one that system bus is busy for data transmission with full system power supply. Idle mode is the scenario when there is no activity on the bus, M-PHY line status could be SLEEP（Low-Speed negative differential signal Diff_n）, STALL(High-Speed negative differential signal Diff_n) or HIBERN8（Hibernate, Differential signal Zero）. However, in Idle mode, the power supply is still on.

上电模式和下电模式非常简单，分别代表电源开和关。电源这里指的是给NAND闪存用的VCC和给UFS控制器用的VCCQ（或者VCCQ2）。活动模式是在电源满负荷供应的时候系统总线忙于数据传输的模式。空闲模式是总线上没有行为的场景，M-PHY的线路状态可以是SLEEP（低速的差分信号负电平Diff_n）, STALL（高速的差分信号负电平Diff_n）或者是HIBERN8（休眠，差分信号0电平）。不过，在空闲模式下电源仍然是开的。

Sleep mode is the one to save power while Deep Sleep mode goes even deeper for power saving. In both modes, VCC might be turned off. Then why we say Deep Sleep mode has got deeper power saving compared to Sleep mode? In sleep mode, M-PHY Line status could be SLEEP, STALL or HIBERN8(recommended). While for Deep Sleep Mode, M-PHY interface is in so called UNPOWERED state. That’s to say Deep Sleep Mode could save power from VCCQ to reduce UFS controller power consuming. It’s the reason why in Deep Power mode, only Hardware Reset or Power cycle is accepted, and no other command are allowed to exit from it, since most UFS controller modules are inactive.

睡眠模式是为了省电，而深度睡眠模式则省电更深一些。两种模式下，VCC都可以关闭。那么为什么说深度睡眠模式相比睡眠模式更省电呢？在睡眠模式下，M-PHY线路状态可以是SLEEP，STALL以及HIBERN8（推荐）。而在深度睡眠模式，M-PHY接口是在所谓断电状态的。也就是说深度睡眠模式可以减少UFS控制器的耗电来从VCCQ上省电。这也是为什么在深度睡眠模式，不允许别的命令而只接受硬件复位或者电源断通来退出这种状态，因为UFS控制器里的模块几乎都不活跃。

SCSI command SSU (Start Stop Unit) is used for power mode change. The basic function of SSU is used for the Start or Stop Logic Unit as its name with parameter START set to ‘1’ or ‘0’。The add-on function of SSU is important as well for power mode switch with parameter PC (Power Condition) setting. PC (Power Condition) 1, 2, 3 and 4 represent Active, Sleep , Power Down and Deep Sleep mode separately.

电源模式改变使用SCSI命令SSU（开始停止单元）。SSU的基本功能就像这个命令的名字一样是开始或者停止逻辑单元，这个是通过设置START参数为‘1’或者‘0’。SSU的附加功能噎同样重要，这个是通过PC（电源条件）参数设定来切换电源模式。PC（电源条件）1，2，3，4分别代表活跃，睡眠，下电和深度睡眠模式。

We do not talk much here on the power mode with prefix presented in dotted box, this is to put emphasis on the 6 main power modes for easy understanding.

这里我们不多谈在虚线框里的带前缀的电源模式，这个也是为了重点强调主要的6种模式以便于理解。