Cold Boot/Resume From S3 When Docked; Undock Sequence; Normal Undock - Intel 6 SERIES CHIPSET - DATASHEET 01-2011 Datasheet

5.22.1.3

Cold Boot/Resume from S3 When Docked

1. When booting and resuming from S3, PLTRST# switches from asserted to
deasserted. This clears the DCKCTL.DA bit and the dock state machines. Because
the dock state machines are reset, the dock is electrically isolated
(HDA_DOCK_EN# deasserted) and DOCK_RST# is asserted.
2. POST BIOS detects that the dock is attached and sets the DCKCTL.DA bit to 1. Note
that at this point CRST# is still asserted so the dock state machine will remain in its
reset state.
3. The Bus Driver clears the STATESTS bits, then deasserts CRST#, waits
approximately 7ms, then checks the STATESTS bits to see which codecs are
present.
4. When CRST# is deasserted, the dock state machine detects that DCKCTL.DA is still
set and the controller hardware sequences through steps to electrically connect the
dock by asserting HDA_DOCK_EN# and then eventually deasserts DOCK_RST#.
This completes within the 7ms mentioned in step 3).
5. The Bus Driver enumerates the codecs present as indicated using the STATESTS
bits.
5.22.1.4

Undock Sequence

There are two possible undocking scenarios. The first is the one that is initiated by the
user that invokes software and gracefully shuts down the dock codecs before they are
undocked. The second is referred to as the "surprise undock" where the user undocks
while the dock codec is running. Both of these situations appear the same to the
controller as it is not cognizant of the "surprise removal". But both sequences will be
discussed here.
5.22.1.5

Normal Undock

1. In the docked quiescent state, the Dock Attach (DCKCTL.DA) bit and the Dock Mate
(DCKSTS.DM) bit are both asserted. The HDA_DOCK_EN# signal is asserted and
HDA_DOCK_RST# is deasserted.
2. The user initiates an undock event through the GUI interface or by pushing a
button. This mechanism is outside the scope of this section of the document. Either
way ACPI BIOS software will be invoked to manage the undock process.
3. ACPI BIOS will call the HD Audio Bus Driver software in order to halt the stream to
the dock codec(s) prior to electrical undocking. If the HD Audio Bus Driver is not
capable of halting the stream to the docked codec, ACPI BIOS will initiate the
hardware undocking sequence as described in the next step while the dock stream
is still running. From this standpoint, the result is similar to the "surprise undock"
scenario where an audio glitch may occur to the docked codec(s) during the undock
process.
4. The ACPI BIOS initiates the hardware undocking sequence by writing a 0 to the
DCKCTL.DA bit.
5. The HD Audio controller asserts HDA_DOCK_RST#. HDA_DOCK_RST# assertion
shall be synchronous to Bit Clock. There are no other timing requirements for
HDA_DOCK_RST# assertion. Note that the HD Audio link reset specification
requirement that the last Frame sync be skipped will not be met.
6. A minimum of 4 Bit Clocks after HDA_DOCK_RST# the controller will deassert
HDA_DOCK_EN# to isolate the dock codec signals from the PCH HD Audio link
signals. HDA_DOCK_EN# is deasserted synchronously to Bit Clock and timed such
that Bit Clock, SYNC, and SDO are low.
7. After this hardware undocking sequence is complete the controller hardware clears
the DCKSTS.DM bit to 0 indicating that the dock is now un-mated. ACPI BIOS
software polls DCKSTS.DM and when it sees DM set, conveys to the end user that
physical undocking can proceed. The controller is now ready for a subsequent
docking event.
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