WM8860 datasheet(28/184 Pages) WOLFSON

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WM8860

Pre-Production

PP, April 2011, Rev 3.2

In D3 (with the link is the Link Reset state), the WM8860 is capable of generating a wake (i.e. a power

state change request). The Controller will respond to the wake by putting the WM8860 through an

initialisation sequence. The initialisation sequence will not change the register settings, so the

WM8860 will still report a power state of D3 but the WM8860 will be able to send responses, including

any unsolicited response(s) that caused a wake to be issued.

As register settings are maintained in the D3/D4 states, the user should be aware that if the WM8860

is brought from D3/D4 to D0 and stream IDs had been previously assigned, data rendering and

capture will commence. If this behaviour is not desired, the user should bring the WM8860 to state

D3 and set the stream IDs to 0, or ensure that stream IDs are set to 0 prior to entering the D3/D4

state.

STREAM START/STOP

Sections 4.5.3 and 4.5.4 of the Intel HD Audio specification describe the starting and stopping of

streams. While the descriptions are sufficient from a controller perspective, there are ambiguities from

a CODEC perspective.

For each stream that goes through the HDA Link, there is a ‘Stream Manager’ module within the

WM8860 whose function is to assemble/disassemble the stream packets within the link frame. The

Stream Manager is disabled while the Stream value in the Converter Stream, Channel Verb is set to

0h. When disabled, the captured data will not be sent on the link, and data from the link will not be

decoded for rendering.

For audio path configuration, it is assumed that the Stream ID is the last register to be set in the

configuration sequence. When Stream ID is set to a non-zero value it has the effect of starting the

stream. On starting the stream, Stream Managers associated with input converters begin transmitting

data on the link, and Stream Managers associated with output converters begin to decode data with

the corresponding stream tag.

Note: Audio paths with mute capabilities may have ‘un-mute’ as the final configuration step. For

these paths, the stream will have started but the audio data will be zeroed until mute has been

disabled.

There are test paths within the WM8860 that do not use the HDA Link. These paths can still be used

when the Stream Manager is disabled.

The Stream Manager is also disabled when the associated converter widget is in power state D1, D2

or D3. Digital converters (i.e. S/PDIF) have a DigEn register bit. When this is set to 0, the associated

stream manager is disabled.

It is assumed that the settings of the Stream Format Verb and Converter Stream, Channel Verb will

not change when a stream is active (with the exception of changing the Stream ID to 0 to terminate

the stream). Changing stream settings while a stream is active is an erroneous action, and may

result in audio corruption.

SDI STREAM ORDER

The order of stream transmission on the SDI link is governed by the CODEC. The WM8860 will

transmit streams with the lowest stream ID value first.

If a stream is started with a stream ID lower than an existing stream, then the new stream is

transmitted earlier in the frame than the existing stream (i.e. the WM8860 auto-shuffles the stream

placement within the frame). This moves the existing stream to further on in the frame than it was

prior to the starting of the new stream. It is assumed that moving streams within a frame is

acceptable to the Controller.

BANDWIDTH CONFLICTS

Sections 5.3.2.2 and 5.3.3.3 of the HD Audio spec describe the scenario of over-subscription of SDO

and SDI bandwidths. It indicates that the final stream on the link is terminated prior to completion, and

further behaviour is undefined.

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