Re: [edk2-devel] [PATCH v1 1/1] MdeModulePkg:Add Warm Reset for Xhc

["zhoucheng" <zhoucheng@phytium.com.cn>]

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Hi Pedro:

//  The description here is the judgment state，we can watch to XHC PORTSC register.
// according to Xhc Spec 5.4.8 chapter Table39.we can knowleadge more information.
// We need to pay attention to the PED CCS and PLS bits of the PORTSC register.

+    State = XhcReadOpReg (Xhc, Offset);
+      if ((( (State & 0x1e0) >> 5) == 6) && ( (State & 3) == 0)) {
↓                                                   ↓
PLS bit                                   PED and CCS bit

//  PLS: Port Link State PED: Port Enabled/Disabled CCS: Current Connect Status
//  If the CCS bit and PED are 0, the device is disconnected and the port is not enabled.
//  If PLS is 6, the controller state machine is abnormal and software intervention is required.

// According to Usb3.2 spec 7.5.2 chapter.Inactive is a state where a link has failed Enhanced SuperSpeed operation.
// The software is required to perform a warm reset operation.
// Therefore, according to the Xhc1.1 spec 5.8 chapter Table39, we can write 1 to its highest bit and perform a hot reset operation to restore the controller.

+        State |= 0x80000000;

For the value of this block, the above explanation has been made, and the discussion can be continued at the same time.

Thanks!

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