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Commit 6cd80d93 authored by Bao D. Nguyen's avatar Bao D. Nguyen
Browse files

dt-bindings: Support turning off UFS's Power Supplies 

Add documentation for the vccq-pwr-collapse-sup and
vccq2-pwr-collapse-sup. If the system supports turning
off UFS's power supplies during system power collapse events,
enabling the feature will turn off the UFS's power supplies
during System Suspend events. During System Resume events,
the UFS power supplies will be turned back on again and the
UFS device will be re-initialized.

Change-Id: I38fd1209bab6c7b008b4b10dc4993ed29ad87727
parent 3321884a

bindings/ufs/ufshcd-pltfrm.txt

+13 −0
Original line number Diff line number Diff line
@@ -80,6 +80,19 @@ Optional properties: 
- reset-names       : describe reset node register, the "rst" corresponds to reset the whole UFS IP.

- force-g4          : forces UFS Host PHY to be initialized in HS-G4



- vccq-pwr-collapse-sup	:

- vccq2-pwr-collapse-sup	: Support turning off UFS's Vccq/Vccq2 power supply during system suspend events.

				  The UFS device will be fully reinitialized during system resume events.

				  The advantage is to save power consumption during system suspend because the

				  entire UFS device is powered off.

				  The tradeoffs are:

				  1. The System Resume time will increase due to full UFS device re-initializations.

				  2. The UFS device life expectancy may be reduced because of the frequent power cycles.

				  Customers should only enable the feature if the SoC supports turning off the UFS

				  power supplies during power collapse events.

				  In addition, customers should evaluate the benefits and tradeoffs of this feature

				  very carefully before enabling it.



Note: If above properties are not defined it can be assumed that the supply

regulators or clocks are always on.