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authorLinus Torvalds <torvalds@linux-foundation.org>2012-01-12 08:00:30 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-01-12 08:00:30 -0800
commita429638cac1e5c656818a45aaff78df7b743004e (patch)
tree0465e0d7a431bff97a3dd5a1f91d9b30c69ae0d8 /Documentation/sound
parent5cf9a4e69c1ff0ccdd1d2b7404f95c0531355274 (diff)
parent9e4ce164ee3a1d07580f017069c25d180b0aa785 (diff)
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound: (526 commits) ASoC: twl6040 - Add method to query optimum PDM_DL1 gain ALSA: hda - Fix the lost power-setup of seconary pins after PM resume ALSA: usb-audio: add Yamaha MOX6/MOX8 support ALSA: virtuoso: add S/PDIF input support for all Xonars ALSA: ice1724 - Support for ooAoo SQ210a ALSA: ice1724 - Allow card info based on model only ALSA: ice1724 - Create capture pcm only for ADC-enabled configurations ALSA: hdspm - Provide unique driver id based on card serial ASoC: Dynamically allocate the rtd device for a non-empty release() ASoC: Fix recursive dependency due to select ATMEL_SSC in SND_ATMEL_SOC_SSC ALSA: hda - Fix the detection of "Loopback Mixing" control for VIA codecs ALSA: hda - Return the error from get_wcaps_type() for invalid NIDs ALSA: hda - Use auto-parser for HP laptops with cx20459 codec ALSA: asihpi - Fix potential Oops in snd_asihpi_cmode_info() ALSA: hdsp - Fix potential Oops in snd_hdsp_info_pref_sync_ref() ALSA: hda/cirrus - support for iMac12,2 model ASoC: cx20442: add bias control over a platform provided regulator ALSA: usb-audio - Avoid flood of frame-active debug messages ALSA: snd-usb-us122l: Delete calls to preempt_disable mfd: Put WM8994 into cache only mode when suspending ... Fix up trivial conflicts in: - arch/arm/mach-s3c64xx/mach-crag6410.c: renamed speyside_wm8962 to tobermory, added littlemill right next to it - drivers/base/regmap/{regcache.c,regmap.c}: duplicate diff that had already come in with other changes in the regmap tree
Diffstat (limited to 'Documentation/sound')
-rw-r--r--Documentation/sound/alsa/HD-Audio-Models.txt15
-rw-r--r--Documentation/sound/alsa/compress_offload.txt188
2 files changed, 189 insertions, 14 deletions
diff --git a/Documentation/sound/alsa/HD-Audio-Models.txt b/Documentation/sound/alsa/HD-Audio-Models.txt
index edad99abec21..c8c54544abc5 100644
--- a/Documentation/sound/alsa/HD-Audio-Models.txt
+++ b/Documentation/sound/alsa/HD-Audio-Models.txt
@@ -42,19 +42,7 @@ ALC260
ALC262
======
- fujitsu Fujitsu Laptop
- benq Benq ED8
- benq-t31 Benq T31
- hippo Hippo (ATI) with jack detection, Sony UX-90s
- hippo_1 Hippo (Benq) with jack detection
- toshiba-s06 Toshiba S06
- toshiba-rx1 Toshiba RX1
- tyan Tyan Thunder n6650W (S2915-E)
- ultra Samsung Q1 Ultra Vista model
- lenovo-3000 Lenovo 3000 y410
- nec NEC Versa S9100
- basic fixed pin assignment w/o SPDIF
- auto auto-config reading BIOS (default)
+ N/A
ALC267/268
==========
@@ -350,7 +338,6 @@ STAC92HD83*
mic-ref Reference board with power management for ports
dell-s14 Dell laptop
dell-vostro-3500 Dell Vostro 3500 laptop
- hp HP laptops with (inverted) mute-LED
hp-dv7-4000 HP dv-7 4000
auto BIOS setup (default)
diff --git a/Documentation/sound/alsa/compress_offload.txt b/Documentation/sound/alsa/compress_offload.txt
new file mode 100644
index 000000000000..c83a835350f0
--- /dev/null
+++ b/Documentation/sound/alsa/compress_offload.txt
@@ -0,0 +1,188 @@
+ compress_offload.txt
+ =====================
+ Pierre-Louis.Bossart <pierre-louis.bossart@linux.intel.com>
+ Vinod Koul <vinod.koul@linux.intel.com>
+
+Overview
+
+Since its early days, the ALSA API was defined with PCM support or
+constant bitrates payloads such as IEC61937 in mind. Arguments and
+returned values in frames are the norm, making it a challenge to
+extend the existing API to compressed data streams.
+
+In recent years, audio digital signal processors (DSP) were integrated
+in system-on-chip designs, and DSPs are also integrated in audio
+codecs. Processing compressed data on such DSPs results in a dramatic
+reduction of power consumption compared to host-based
+processing. Support for such hardware has not been very good in Linux,
+mostly because of a lack of a generic API available in the mainline
+kernel.
+
+Rather than requiring a compability break with an API change of the
+ALSA PCM interface, a new 'Compressed Data' API is introduced to
+provide a control and data-streaming interface for audio DSPs.
+
+The design of this API was inspired by the 2-year experience with the
+Intel Moorestown SOC, with many corrections required to upstream the
+API in the mainline kernel instead of the staging tree and make it
+usable by others.
+
+Requirements
+
+The main requirements are:
+
+- separation between byte counts and time. Compressed formats may have
+ a header per file, per frame, or no header at all. The payload size
+ may vary from frame-to-frame. As a result, it is not possible to
+ estimate reliably the duration of audio buffers when handling
+ compressed data. Dedicated mechanisms are required to allow for
+ reliable audio-video synchronization, which requires precise
+ reporting of the number of samples rendered at any given time.
+
+- Handling of multiple formats. PCM data only requires a specification
+ of the sampling rate, number of channels and bits per sample. In
+ contrast, compressed data comes in a variety of formats. Audio DSPs
+ may also provide support for a limited number of audio encoders and
+ decoders embedded in firmware, or may support more choices through
+ dynamic download of libraries.
+
+- Focus on main formats. This API provides support for the most
+ popular formats used for audio and video capture and playback. It is
+ likely that as audio compression technology advances, new formats
+ will be added.
+
+- Handling of multiple configurations. Even for a given format like
+ AAC, some implementations may support AAC multichannel but HE-AAC
+ stereo. Likewise WMA10 level M3 may require too much memory and cpu
+ cycles. The new API needs to provide a generic way of listing these
+ formats.
+
+- Rendering/Grabbing only. This API does not provide any means of
+ hardware acceleration, where PCM samples are provided back to
+ user-space for additional processing. This API focuses instead on
+ streaming compressed data to a DSP, with the assumption that the
+ decoded samples are routed to a physical output or logical back-end.
+
+ - Complexity hiding. Existing user-space multimedia frameworks all
+ have existing enums/structures for each compressed format. This new
+ API assumes the existence of a platform-specific compatibility layer
+ to expose, translate and make use of the capabilities of the audio
+ DSP, eg. Android HAL or PulseAudio sinks. By construction, regular
+ applications are not supposed to make use of this API.
+
+
+Design
+
+The new API shares a number of concepts with with the PCM API for flow
+control. Start, pause, resume, drain and stop commands have the same
+semantics no matter what the content is.
+
+The concept of memory ring buffer divided in a set of fragments is
+borrowed from the ALSA PCM API. However, only sizes in bytes can be
+specified.
+
+Seeks/trick modes are assumed to be handled by the host.
+
+The notion of rewinds/forwards is not supported. Data committed to the
+ring buffer cannot be invalidated, except when dropping all buffers.
+
+The Compressed Data API does not make any assumptions on how the data
+is transmitted to the audio DSP. DMA transfers from main memory to an
+embedded audio cluster or to a SPI interface for external DSPs are
+possible. As in the ALSA PCM case, a core set of routines is exposed;
+each driver implementer will have to write support for a set of
+mandatory routines and possibly make use of optional ones.
+
+The main additions are
+
+- get_caps
+This routine returns the list of audio formats supported. Querying the
+codecs on a capture stream will return encoders, decoders will be
+listed for playback streams.
+
+- get_codec_caps For each codec, this routine returns a list of
+capabilities. The intent is to make sure all the capabilities
+correspond to valid settings, and to minimize the risks of
+configuration failures. For example, for a complex codec such as AAC,
+the number of channels supported may depend on a specific profile. If
+the capabilities were exposed with a single descriptor, it may happen
+that a specific combination of profiles/channels/formats may not be
+supported. Likewise, embedded DSPs have limited memory and cpu cycles,
+it is likely that some implementations make the list of capabilities
+dynamic and dependent on existing workloads. In addition to codec
+settings, this routine returns the minimum buffer size handled by the
+implementation. This information can be a function of the DMA buffer
+sizes, the number of bytes required to synchronize, etc, and can be
+used by userspace to define how much needs to be written in the ring
+buffer before playback can start.
+
+- set_params
+This routine sets the configuration chosen for a specific codec. The
+most important field in the parameters is the codec type; in most
+cases decoders will ignore other fields, while encoders will strictly
+comply to the settings
+
+- get_params
+This routines returns the actual settings used by the DSP. Changes to
+the settings should remain the exception.
+
+- get_timestamp
+The timestamp becomes a multiple field structure. It lists the number
+of bytes transferred, the number of samples processed and the number
+of samples rendered/grabbed. All these values can be used to determine
+the avarage bitrate, figure out if the ring buffer needs to be
+refilled or the delay due to decoding/encoding/io on the DSP.
+
+Note that the list of codecs/profiles/modes was derived from the
+OpenMAX AL specification instead of reinventing the wheel.
+Modifications include:
+- Addition of FLAC and IEC formats
+- Merge of encoder/decoder capabilities
+- Profiles/modes listed as bitmasks to make descriptors more compact
+- Addition of set_params for decoders (missing in OpenMAX AL)
+- Addition of AMR/AMR-WB encoding modes (missing in OpenMAX AL)
+- Addition of format information for WMA
+- Addition of encoding options when required (derived from OpenMAX IL)
+- Addition of rateControlSupported (missing in OpenMAX AL)
+
+Not supported:
+
+- Support for VoIP/circuit-switched calls is not the target of this
+ API. Support for dynamic bit-rate changes would require a tight
+ coupling between the DSP and the host stack, limiting power savings.
+
+- Packet-loss concealment is not supported. This would require an
+ additional interface to let the decoder synthesize data when frames
+ are lost during transmission. This may be added in the future.
+
+- Volume control/routing is not handled by this API. Devices exposing a
+ compressed data interface will be considered as regular ALSA devices;
+ volume changes and routing information will be provided with regular
+ ALSA kcontrols.
+
+- Embedded audio effects. Such effects should be enabled in the same
+ manner, no matter if the input was PCM or compressed.
+
+- multichannel IEC encoding. Unclear if this is required.
+
+- Encoding/decoding acceleration is not supported as mentioned
+ above. It is possible to route the output of a decoder to a capture
+ stream, or even implement transcoding capabilities. This routing
+ would be enabled with ALSA kcontrols.
+
+- Audio policy/resource management. This API does not provide any
+ hooks to query the utilization of the audio DSP, nor any premption
+ mechanisms.
+
+- No notion of underun/overrun. Since the bytes written are compressed
+ in nature and data written/read doesn't translate directly to
+ rendered output in time, this does not deal with underrun/overun and
+ maybe dealt in user-library
+
+Credits:
+- Mark Brown and Liam Girdwood for discussions on the need for this API
+- Harsha Priya for her work on intel_sst compressed API
+- Rakesh Ughreja for valuable feedback
+- Sing Nallasellan, Sikkandar Madar and Prasanna Samaga for
+ demonstrating and quantifying the benefits of audio offload on a
+ real platform.