On 1/11/2019 11:32 PM, Pierre-Louis Bossart wrote:
On 1/11/19 11:22 AM, Sameer Pujar wrote:
Background
==========
Azalia Controller fetches command and audio data via DMA and send them
to codec through SDO(Serial Data Out) lines. SDO is for outboung and it
broadcasts to all codecs. There is atleast one SDO line present, but
there can be multiple SDO lines supported for extended bandwidth. This
is essential when a platform supports multiple hdmi/dp sinks and there
is a requirement for higher resolution audio playback. In such cases
simultaneous audio playback data can be striped across multiple SDOs.
Global Capabilities(GCAP) Register indicates the capabilities of the
controller. Bits 2:1 of GCAP can be read to know the number of supported
SDO lines (below is from HD audio spec)
00: 1 SDO
01: 2 SDO
10: 4 SDO
11: Reserved
Stripe control verb reports and controls the stripe capability of an
Audio Output Converter. This verb needs to be implemented only for an
audio output converter and only if the stripe bit of the Audio Widget
Capabilities parameter is 1.
Stripe control: get code(0xf24) and set code(0x724)
the series look ok (one minor comment on operator precedence) and
aligned with my understanding of the HDaudio 1.0a spec.
That said you made no mention of the Stripe bit (figure 86) and
fields 22:20 (Stripe capability) in Figure 75, so it's not clear to me
if the support added in this patchset is sufficient or if there is
additional logic to be set.
Stripe bit is part of Audio Widget Capability parameter and is mentioned
above in the last section of background. Patch-5(v2) checks for the
stripe bit, before sending stripe control verb.
As far as stripe control register is concerned (22:20), I don't think
any SW programming is required for this.
There is also a difference between what the controller supports and
the actual board layout, so it's not clear if the GCAP are really the
raw capabilities or the ones filtered by BIOS folks to reflect the
actual platform hardware implementation.
-Pierre
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