RE: [PATCH v5 2/4] PCI: layerscape: Add suspend/resume for ls1021a

From: Frank Li <frank.li@nxp.com>
Subject: [PATCH v5 2/4] PCI: layerscape: Add suspend/resume for ls1021a

Add suspend/resume support for Layerscape LS1021a.

In the suspend path, PME_Turn_Off message is sent to the endpoint to
transition the link to L2/L3_Ready state. In this SoC, there is no way to check if
the controller has received the PME_To_Ack from the endpoint or not. So to be
on the safer side, the driver just waits for PCIE_PME_TO_L2_TIMEOUT_US
before asserting the SoC specific PMXMTTURNOFF bit to complete the
PME_Turn_Off handshake. Then the link would enter L2/L3 state depending on
the VAUX supply.

In the resume path, the link is brought back from L2 to L0 by doing a software
reset.

Signed-off-by: Frank Li <Frank.Li@nxp.com>

Acked-by:  Roy Zang <Roy.Zang@nxp.com>
Roy