by Wesley Cheng

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Subject: Re: [PATCH v22 00/38] Introduce QC USB SND audio offloading support

On 5/23/2024 5:10 PM, Wesley Cheng wrote:
> Requesting to see if we can get some Acked-By tags, and merge on usb-next.
>

Hi Takashi/Mark/Mathias,

Since this series includes dependencies from multiple SW areas and
maintainers, can we consider getting some ACK'ed by/Reviewed by tags if
things look good? I believe Greg mentioned he would be open to add
these all on usb-next when we get these tags.

That would probably make the submission easier to handle.

Thanks
Wesley Cheng

> Several Qualcomm based chipsets can support USB audio offloading to a
> dedicated audio DSP, which can take over issuing transfers to the USB
> host controller. The intention is to reduce the load on the main
> processors in the SoC, and allow them to be placed into lower power modes.
> There are several parts to this design:
> 1. Adding ASoC binding layer
> 2. Create a USB backend for Q6DSP
> 3. Introduce XHCI interrupter support
> 4. Create vendor ops for the USB SND driver
>
> USB | ASoC
> --------------------------------------------------------------------
> | _________________________
> | |sm8250 platform card |
> | |_________________________|
> | | |
> | ___V____ ____V____
> | |Q6USB | |Q6AFE |
> | |"codec" | |"cpu" |
> | |________| |_________|
> | ^ ^ ^
> | | |________|
> | ___V____ |
> | |SOC-USB | |
> ________ ________ | | |
> |USB SND |<--->|QC offld|<------------>|________| |
> |(card.c)| | |<---------- |
> |________| |________|___ | | |
> ^ ^ | | | ____________V_________
> | | | | | |APR/GLINK |
> __ V_______________V_____ | | | |______________________|
> |USB SND (endpoint.c) | | | | ^
> |_________________________| | | | |
> ^ | | | ___________V___________
> | | | |->|audio DSP |
> ___________V_____________ | | |_______________________|
> |XHCI HCD |<- |
> |_________________________| |
>
>
> Adding ASoC binding layer:
> soc-usb: Intention is to treat a USB port similar to a headphone jack.
> The port is always present on the device, but cable/pin status can be
> enabled/disabled. Expose mechanisms for USB backend ASoC drivers to
> communicate with USB SND.
>
> Create a USB backend for Q6DSP:
> q6usb: Basic backend driver that will be responsible for maintaining the
> resources needed to initiate a playback stream using the Q6DSP. Will
> be the entity that checks to make sure the connected USB audio device
> supports the requested PCM format. If it does not, the PCM open call will
> fail, and userpsace ALSA can take action accordingly.
>
> Introduce XHCI interrupter support:
> XHCI HCD supports multiple interrupters, which allows for events to be routed
> to different event rings. This is determined by "Interrupter Target" field
> specified in Section "6.4.1.1 Normal TRB" of the XHCI specification.
>
> Events in the offloading case will be routed to an event ring that is assigned
> to the audio DSP.
>
> Create vendor ops for the USB SND driver:
> qc_audio_offload: This particular driver has several components associated
> with it:
> - QMI stream request handler
> - XHCI interrupter and resource management
> - audio DSP memory management
>
> When the audio DSP wants to enable a playback stream, the request is first
> received by the ASoC platform sound card. Depending on the selected route,
> ASoC will bring up the individual DAIs in the path. The Q6USB backend DAI
> will send an AFE port start command (with enabling the USB playback path), and
> the audio DSP will handle the request accordingly.
>
> Part of the AFE USB port start handling will have an exchange of control
> messages using the QMI protocol. The qc_audio_offload driver will populate the
> buffer information:
> - Event ring base address
> - EP transfer ring base address
>
> and pass it along to the audio DSP. All endpoint management will now be handed
> over to the DSP, and the main processor is not involved in transfers.
>
> Overall, implementing this feature will still expose separate sound card and PCM
> devices for both the platorm card and USB audio device:
> 0 [SM8250MTPWCD938]: sm8250 - SM8250-MTP-WCD9380-WSA8810-VA-D
> SM8250-MTP-WCD9380-WSA8810-VA-DMIC
> 1 [Audio ]: USB-Audio - USB Audio
> Generic USB Audio at usb-xhci-hcd.1.auto-1.4, high speed
>
> This is to ensure that userspace ALSA entities can decide which route to take
> when executing the audio playback. In the above, if card#1 is selected, then
> USB audio data will take the legacy path over the USB PCM drivers, etc...
>
> This feature was validated using:
> - tinymix: set/enable the multimedia path to route to USB backend
> - tinyplay: issue playback on platform card
>
> Changelog
> --------------------------------------------
> Changes in v22:
> - Removed components tag for the ASoC platform card, as the USB SND kcontrol for
> notifying userspace of offload capable card achieves similar results.
> - Due to the above, had to remove the review-by tag for the RST documentation,
> as changes were made to remove the components tag section.
> - Took in feedback to make the SOC USB add/remove ports void.
> - Fixed an issue w/ the USB SND kcontrol management for devices that have multi
> UAC interfaces. (would attempt to create the kcontrol more than once)
> - Modified SOC USB card and PCM index select to be based off the num_supported
> streams that is specified by the USB BE DAI.
> - Modified comments on selecting the latest USB headset for offloading.
>
> Changes in v21:
> - Added an offload jack disable path from the ASoC platform driver and SOC USB.
> - Refactored some of the existing SOC USB context look up APIs and created some
> new helpers to search for the USB context.
> - Renamed snd_soc_usb_find_format to snd_soc_usb_find_supported_format
> - Removed some XHCI sideband calls that would allow clients to actually enable
> the IRQ line associated w/ the secondary interrupter. This is removed because
> there are other dependencies that are required for that to happen, which are not
> covered as part of this series, and to avoid confusion.
> - Due to the above, removed the need to export IMOD setting, and enable/disable
> interrupter APIs.
>
> Changes in v20:
> - Fixed up some formatting changes pointed out in the usb.rst
> - Added SB null check during XHCI sideband unregister in case caller passes
> improper argument (xhci_sideband_unregister())
>
> Changes in v19:
> - Rebased to usb-next to account for some new changes in dependent drivers.
>
> Changes in v18:
> - Rebased to usb-next, which merged in part of the series. Removed these patches.
> - Reworked Kconfigs for the ASoC USB related components from QCOM Q6DSP drivers
> to keep dependencies in place for SoC USB and USB SND.
> - Removed the repurposing of the stop ep sync API into existing XHCI operations.
> This will be solely used by the XHCI sideband for now.
>
> Changes in v17:
> - Fixed an issue where one patch was squashed into another.
> - Re-added some kconfig checks for helpers exposed in USB SND for the soc usb
> driver, after running different kconfigs.
>
> Changes in v16:
> - Modified some code layer dependencies so that soc usb can be split as a separate
> module.
> - Split the kcontrols from ASoC QCOM common layer into a separate driver
> - Reworked SOC USB kcontrols for controlling card + pcm offload routing and status
> so that there are individual controls for card and pcm devices.
> - Added a kcontrol remove API in SOC USB to remove the controls on the fly. This
> required to add some kcontrol management to SOC USB.
> - Removed the disconnect work and workqueue for the QC USB offload as it is not
> required, since QMI interface driver ensures events are handled in its own WQ.
>
> Changes in v15:
> - Removed some already merged XHCI changes
> - Separated SOC USB driver from being always compiled into SOC core. Now
> configurable from kconfig.
> - Fixed up ASoC kcontrol naming to fit guidelines.
> - Removed some unnecessary dummy ifdefs.
> - Moved usb snd offload capable kcontrol to be initialized by the platform offloading
> driver.
>
> Changes in v14:
> - Cleaned up some USB SND related feedback:
> - Renamed SNDUSB OFFLD playback available --> USB offload capable card
> - Fixed locking while checking if stream is in use
> - Replaced some mutex pairs with guard(mutex)
>
> Changes in v13:
> - Pulled in secondary/primary interrupter rework from Mathias from:
> https://git.kernel.org/pub/scm/linux/kernel/git/mnyman/xhci.git/log/drivers/usb/host?h=fix_eventhandling
> - Did some cleanup and commit message updates, and tested on current code base.
> - Added mutex locking to xhci sideband to help prevent any race conditions, esp. for when accessing shared
> references.
> - Addresed concerns from Hillf about gfp_flags and locking used in qc_usb_audio_offload.
> - Rebased onto usb-next
>
> Changes in v12:
> - Updated copyright year to 2024. Happy new years!
> - Fixed newline format on mixer offload driver.
>
> Changes in v11:
> - Modified QMI format structures to be const
>
> Changes in v10:
> - Added new mixer for exposing kcontrol for sound card created by USB SND. This
> allows for applications to know which platform sound card has offload support.
> Will return the card number.
> - Broke down and cleaned up some functions/APIs within qc_audio_offload driver.
> - Exported xhci_initialize_ring_info(), and modified XHCI makefile to allow for
> the XHCI sideband to exist as a module.
> - Reworked the jack registration and moved it to the QCOM platform card driver,
> ie sm8250.
> - Added an SOC USB API to fetch a standard component tag that can be appended to
> the platform sound card. Added this tag to sm8250 if any USB path exists within
> the DT node.
> - Moved kcontrols that existed in the Q6USB driver, and made it a bit more generic,
> so that naming can be standardized across solutions. SOC USB is now responsible
> for creation of these kcontrols.
> - Added a SOC USB RST document explaining some code flows and implementation details
> so that other vendors can utilize the framework.
> - Addressed a case where USB device connection events are lost if usb offload driver
> (qc_audio_offload) is not probed when everything else has been initialized, ie
> USB SND, SOC USB and ASoC sound card. Add a rediscover device call during module
> init, to ensure that connection events will be propagated.
> - Rebased to usb-next.
>
> Changes in v9:
> - Fixed the dt binding check issue with regards to num-hc-interrupters.
>
> Changes in v8:
> - Cleaned up snd_soc_usb_find_priv_data() based on Mark's feedback. Removed some of
> the duplicate looping code that was present on previous patches. Also renamed the API.
> - Integrated Mathias' suggestions on his new sideband changes:
> https://git.kernel.org/pub/scm/linux/kernel/git/mnyman/xhci.git/log/?h=feature_interrupters
> - Addressed some of Mathias' fixme tags, such as:
> - Resetting transfer ring dequeue/enqueue pointers
> - Issuing stop endpoint command during ep removal
> - Reset ERDP properly to first segment ring during interrupter removal. (this is currently
> just being cleared to 0, but should be pointing to a valid segment if controller is still
> running.
>
> Changes in v7:
> - Fixed dt check error for q6usb bindings
> - Updated q6usb property from qcom,usb-audio-intr-num --> qcom,usb-audio-intr-idx
> - Removed separate DWC3 HC interrupters num property, and place limits to XHCI one.
> - Modified xhci_ring_to_sgtable() to use assigned IOVA/DMA address to fetch pages, as
> it is not ensured event ring allocated is always done in the vmalloc range.
>
> Changes in v6:
> - Fixed limits and description on several DT bindings (XHCI and Q6USB)
> - Fixed patch subjects to follow other ALSA/ASoC notations.
>
> USB SND
> - Addressed devices which expose multiple audio (UAC) interfaces. These devices will
> create a single USB sound card with multiple audio streams, and receive multiple
> interface probe routines. QC offload was not properly considering cases with multiple
> probe calls.
> - Renamed offload module name and kconfig to fit within the SND domain.
> - Renamed attach/detach endpoint API to keep the hw_params notation.
>
> Changes in v5:
> - Removed some unnescessary files that were included
> - Fixed some typos mentioned
> - Addressed dt-binding issues and added hc-interrupters definition to usb-xhci.yaml
>
> XHCI:
> - Moved secondary skip events API to xhci-ring and updated implementation
> - Utilized existing XHCI APIs, such as inc_deq and xhci_update_erst_dequeue()
>
> USB SND
> - Renamed and reworked the APIs in "sound: usb: Export USB SND APIs for modules" patch to
> include suggestions to utilize snd_usb_hw_params/free and to avoid generic naming.
> - Added a resume_cb() op for completion sake.
> - Addressed some locking concerns with regards to when registering for platform hooks.
> - Added routine to disconnect all offloaded devices during module unbind.
>
> ASoC
> - Replaced individual PCM parameter arguments in snd_soc_usb_connect() with new
> snd_soc_usb_device structure to pass along PCM info.
> - Modified snd_jack set report to notify HEADPHONE event, as we do not support record path.
>
> Changes in v4:
> - Rebased to xhci/for-usb-next
> - Addressed some dt-bindings comments
>
> XHCI:
> - Pulled in latest changes from Mathias' feature_interrupters branch:
> https://git.kernel.org/pub/scm/linux/kernel/git/mnyman/xhci.git/log/?h=feature_interrupters
>
> - Fixed commit text and signage for the XHCI sideband/interrupter related changes
> - Added some logic to address the FIXME tags mentioned throughout the commits, such
> as handling multi segment rings and building the SGT, locking concerns, and ep
> cleanup operations.
> - Removed some fixme tags for conditions that may not be needed/addressed.
> - Repurposed the new endpoint stop sync API to be utilized in other places.
> - Fixed potential compile issue if XHCI sideband config is not defined.
>
> ASoC:
> - Added sound jack control into the Q6USB driver. Allows for userpsace to know when
> an offload capable device is connected.
>
> USB SND:
> - Avoided exporting _snd_pcm_hw_param_set based on Takashi's recommendation.
> - Split USB QMI packet header definitions into a separate commit. This is used to
> properly allow the QMI interface driver to parse and route QMI packets accordingly
> - Added a "depends on" entry when enabling QC audio offload to avoid compile time
> issues.
>
> Changes in v3:
> - Changed prefix from RFC to PATCH
> - Rebased entire series to usb-next
> - Updated copyright years
>
> XHCI:
> - Rebased changes on top of XHCI changes merged into usb-next, and only added
> changes that were still under discussion.
> - Added change to read in the "num-hc-interrupters" device property.
>
> ASoC:
> - qusb6 USB backend
> - Incorporated suggestions to fetch iommu information with existing APIs
> - Added two new sound kcontrols to fetch offload status and offload device
> selection.
> - offload status - will return the card and pcm device in use
> tinymix -D 0 get 1 --> 1, 0 (offload in progress on card#1 pcm#0)
>
> - device selection - set the card and pcm device to enable offload on. Ex.:
> tinymix -D 0 set 1 2 0 --> sets offload on card#2 pcm#0
> (this should be the USB card)
>
> USB SND:
> - Fixed up some locking related concerns for registering platform ops.
> - Moved callbacks under the register_mutex, so that
> - Modified APIs to properly pass more information about the USB SND device, so
> that the Q6USB backend can build a device list/map, in order to monitor offload
> status and device selection.
>
> Changes in v2:
>
> XHCI:
> - Replaced XHCI and HCD changes with Mathias' XHCI interrupter changes
> in his tree:
> https://git.kernel.org/pub/scm/linux/kernel/git/mnyman/xhci.git/log/?h=feature_interrupters
>
> Adjustments made to Mathias' changes:
> - Created xhci-intr.h to export/expose interrupter APIs versus exposing xhci.h.
> Moved dependent structures to this file as well. (so clients can parse out
> information from "struct xhci_interrupter")
> - Added some basic locking when requesting interrupters.
> - Fixed up some sanity checks.
> - Removed clearing of the ERSTBA during freeing of the interrupter. (pending
> issue where SMMU fault occurs if DMA addr returned is 64b - TODO)
>
> - Clean up pending events in the XHCI secondary interrupter. While testing USB
> bus suspend, it was seen that on bus resume, the xHCI HC would run into a command
> timeout.
> - Added offloading APIs to xHCI to fetch transfer and event ring information.
>
> ASoC:
> - Modified soc-usb to allow for multiple USB port additions. For this to work,
> the USB offload driver has to have a reference to the USB backend by adding
> a "usb-soc-be" DT entry to the device saved into XHCI sysdev.
> - Created separate dt-bindings for defining USB_RX port.
> - Increased APR timeout to accommodate the situation where the AFE port start
> command could be delayed due to having to issue a USB bus resume while
> handling the QMI stream start command.
>
> USB SND:
> - Added a platform ops during usb_audio_suspend(). This allows for the USB
> offload driver to halt the audio stream when system enters PM suspend. This
> ensures the audio DSP is not issuing transfers on the USB bus.
> - Do not override platform ops if they are already populated.
> - Introduce a shared status variable between the USB offload and USB SND layers,
> to ensure that only one path is active at a time. If the USB bus is occupied,
> then userspace is notified that the path is busy.
>
> Mathias Nyman (2):
> xhci: add helper to stop endpoint and wait for completion
> xhci: sideband: add initial api to register a sideband entity
>
> Wesley Cheng (36):
> usb: host: xhci: Repurpose event handler for skipping interrupter
> events
> usb: xhci: Allow for secondary interrupter to set IMOD
> usb: host: xhci-mem: Cleanup pending secondary event ring events
> usb: host: xhci-mem: Allow for interrupter clients to choose specific
> index
> ASoC: Add SOC USB APIs for adding an USB backend
> ASoC: dt-bindings: qcom,q6dsp-lpass-ports: Add USB_RX port
> ASoC: qcom: qdsp6: Introduce USB AFE port to q6dsp
> ASoC: qdsp6: q6afe: Increase APR timeout
> ASoC: qcom: qdsp6: Add USB backend ASoC driver for Q6
> ALSA: usb-audio: Introduce USB SND platform op callbacks
> ALSA: usb-audio: Export USB SND APIs for modules
> ALSA: usb-audio: Save UAC sample size information
> usb: dwc3: Specify maximum number of XHCI interrupters
> usb: host: xhci-plat: Set XHCI max interrupters if property is present
> ALSA: usb-audio: qcom: Add USB QMI definitions
> ALSA: usb-audio: qcom: Introduce QC USB SND offloading support
> ALSA: usb-audio: Check for support for requested audio format
> ASoC: usb: Add PCM format check API for USB backend
> ASoC: qcom: qdsp6: Ensure PCM format is supported by USB audio device
> ALSA: usb-audio: Prevent starting of audio stream if in use
> ALSA: usb-audio: Do not allow USB offload path if PCM device is in use
> ASoC: dt-bindings: Update example for enabling USB offload on SM8250
> ALSA: usb-audio: qcom: Populate PCM and USB chip information
> ASoC: qcom: qdsp6: Add support to track available USB PCM devices
> ASoC: Introduce SND kcontrols to select sound card and PCM device
> ASoC: qcom: qdsp6: Add SOC USB offload select get/put callbacks
> ASoC: Introduce SND kcontrols to track USB offloading state
> ASoC: qcom: qdsp6: Add PCM ops to track current state
> ASoC: usb: Create SOC USB SND jack kcontrol
> ASoC: qcom: qdsp6: Add headphone jack for offload connection status
> ASoC: usb: Fetch ASoC sound card information
> ALSA: usb-audio: Add USB offloading capable kcontrol
> ALSA: usb-audio: Allow for rediscovery of connected USB SND devices
> ALSA: usb-audio: qcom: Use card and PCM index from QMI request
> ASoC: usb: Rediscover USB SND devices on USB port add
> ASoC: doc: Add documentation for SOC USB
>
> .../bindings/sound/qcom,sm8250.yaml | 15 +
> Documentation/sound/soc/index.rst | 1 +
> Documentation/sound/soc/usb.rst | 603 ++++++
> drivers/usb/dwc3/core.c | 12 +
> drivers/usb/dwc3/core.h | 2 +
> drivers/usb/dwc3/host.c | 3 +
> drivers/usb/host/Kconfig | 9 +
> drivers/usb/host/Makefile | 2 +
> drivers/usb/host/xhci-mem.c | 36 +-
> drivers/usb/host/xhci-plat.c | 2 +
> drivers/usb/host/xhci-ring.c | 50 +-
> drivers/usb/host/xhci-sideband.c | 418 ++++
> drivers/usb/host/xhci.c | 43 +-
> drivers/usb/host/xhci.h | 18 +-
> .../sound/qcom,q6dsp-lpass-ports.h | 1 +
> include/linux/usb/xhci-sideband.h | 68 +
> include/sound/q6usboffload.h | 20 +
> include/sound/soc-usb.h | 188 ++
> sound/soc/Kconfig | 10 +
> sound/soc/Makefile | 2 +
> sound/soc/qcom/Kconfig | 15 +
> sound/soc/qcom/Makefile | 2 +
> sound/soc/qcom/qdsp6/Makefile | 1 +
> sound/soc/qcom/qdsp6/q6afe-dai.c | 60 +
> sound/soc/qcom/qdsp6/q6afe.c | 193 +-
> sound/soc/qcom/qdsp6/q6afe.h | 36 +-
> sound/soc/qcom/qdsp6/q6dsp-lpass-ports.c | 23 +
> sound/soc/qcom/qdsp6/q6dsp-lpass-ports.h | 1 +
> sound/soc/qcom/qdsp6/q6routing.c | 9 +
> sound/soc/qcom/qdsp6/q6usb.c | 417 ++++
> sound/soc/qcom/sm8250.c | 23 +-
> sound/soc/qcom/usb_offload_utils.c | 55 +
> sound/soc/qcom/usb_offload_utils.h | 29 +
> sound/soc/soc-usb.c | 684 ++++++
> sound/usb/Kconfig | 25 +
> sound/usb/Makefile | 2 +-
> sound/usb/card.c | 109 +
> sound/usb/card.h | 15 +
> sound/usb/endpoint.c | 1 +
> sound/usb/format.c | 1 +
> sound/usb/helper.c | 1 +
> sound/usb/pcm.c | 104 +-
> sound/usb/pcm.h | 11 +
> sound/usb/qcom/Makefile | 6 +
> sound/usb/qcom/mixer_usb_offload.c | 65 +
> sound/usb/qcom/mixer_usb_offload.h | 17 +
> sound/usb/qcom/qc_audio_offload.c | 1915 +++++++++++++++++
> sound/usb/qcom/usb_audio_qmi_v01.c | 892 ++++++++
> sound/usb/qcom/usb_audio_qmi_v01.h | 162 ++
> 49 files changed, 6327 insertions(+), 50 deletions(-)
> create mode 100644 Documentation/sound/soc/usb.rst
> create mode 100644 drivers/usb/host/xhci-sideband.c
> create mode 100644 include/linux/usb/xhci-sideband.h
> create mode 100644 include/sound/q6usboffload.h
> create mode 100644 include/sound/soc-usb.h
> create mode 100644 sound/soc/qcom/qdsp6/q6usb.c
> create mode 100644 sound/soc/qcom/usb_offload_utils.c
> create mode 100644 sound/soc/qcom/usb_offload_utils.h
> create mode 100644 sound/soc/soc-usb.c
> create mode 100644 sound/usb/qcom/Makefile
> create mode 100644 sound/usb/qcom/mixer_usb_offload.c
> create mode 100644 sound/usb/qcom/mixer_usb_offload.h
> create mode 100644 sound/usb/qcom/qc_audio_offload.c
> create mode 100644 sound/usb/qcom/usb_audio_qmi_v01.c
> create mode 100644 sound/usb/qcom/usb_audio_qmi_v01.h
>