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Neil Armstrong <neil.armstrong@linaro.org> says: The Qualcom SM8650 based Ayaneo Pocket S2 gaming device has a set of 2 WSA speakers connected on the WSA2 lines. But the Audioreach DSP only handles WSA2 in pair with the WSA interface by using the upper bits of the active_channels_mask for WSA2 and the lower bits for WSA: __________________________________________________ | Bits | 3 | 2 | 1 | 0 | --------------------------------------------------- | Line | WSA2 Ch2 | WSA2 Ch1 | WSA Ch2 | WSA Ch1 | --------------------------------------------------- Setting only the WSA2 upper bits is perfectly valid and functional but the current Audioreach code builds the bitmask from the channels count with: active_channels_mask = (1 << num_channels) - 1; In order to enable the WSA2 bits the channel count should be 4, but the lower WSA bits are then also enabled and the DSP errors out when trying to play on the disabled WSA interface. A solution would've been to add a fake WSA2 topology element which would be translated into the top bits only, but it's not clean and add some special exceptions in the generic Audioreach code. The solution suggested by Srinivas is to use the channel mapping to set this bitmask. This works but makes all the other calls using the channel mapping fail because the DSP requires the channel_mapping table to start from index 0 and using num_channel length in order to apply the mapping on the active_channels_mask bits in order. So if you have an active_channels_mask like: _______________________ | Bits | 3 | 2 | 1 | 0 | ------------------------- | Mask | 1 | 1 | 0 | 0 | ------------------------ And the channel mapping: _________________________________ | Channel | 3 | 2 | 1 | 0 | ----------------------------------- | Mapping | FR | FL | NULL | NULL | ----------------------------------- Will need to be converted to: ____________________ | Channel | 1 | 0 | --------------------- | Mapping | FR | FL | --------------------- And the DSP will map FR on WSA2 Ch2 and FL on WSA2 Ch1 as: _________________________________ | Line | WSA2 Ch2 | WSA2 Ch1 | ---------------------------------- | Mapping | FR | FL | ---------------------------------- So we need to skip the empty channel mapping entries in all other users of the channel_map to build valid channel_mapping tables. This should not break any other usecases since the default channel mapping always start from index 0, and will add flexibilty to allow some special non linear mapping for other interfaces as well. Finally we add a special prepare callback for the Ayaneo PS2 sound card which sets the custom channel mapping for the WSA interface to make audio work properly on the gaming device. Link: https://patch.msgid.link/20260728-topic-sm8650-ayaneo-pocket-s2-wsa2-fix-v3-0-b29f44720178@linaro.org |
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Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. Quick Start ----------- * Report a bug: See Documentation/admin-guide/reporting-issues.rst * Get the latest kernel: https://kernel.org * Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst * Join the community: https://lore.kernel.org/ Essential Documentation ----------------------- All users should be familiar with: * Building requirements: Documentation/process/changes.rst * Code of Conduct: Documentation/process/code-of-conduct.rst * License: See COPYING Documentation can be built with make htmldocs or viewed online at: https://www.kernel.org/doc/html/latest/ Who Are You? ============ Find your role below: * New Kernel Developer - Getting started with kernel development * Academic Researcher - Studying kernel internals and architecture * Security Expert - Hardening and vulnerability analysis * Backport/Maintenance Engineer - Maintaining stable kernels * System Administrator - Configuring and troubleshooting * Maintainer - Leading subsystems and reviewing patches * Hardware Vendor - Writing drivers for new hardware * Distribution Maintainer - Packaging kernels for distros * AI Coding Assistant - LLMs and AI-powered development tools For Specific Users ================== New Kernel Developer -------------------- Welcome! Start your kernel development journey here: * Getting Started: Documentation/process/development-process.rst * Your First Patch: Documentation/process/submitting-patches.rst * Coding Style: Documentation/process/coding-style.rst * Build System: Documentation/kbuild/index.rst * Development Tools: Documentation/dev-tools/index.rst * Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst * Core APIs: Documentation/core-api/index.rst Academic Researcher ------------------- Explore the kernel's architecture and internals: * Researcher Guidelines: Documentation/process/researcher-guidelines.rst * Memory Management: Documentation/mm/index.rst * Scheduler: Documentation/scheduler/index.rst * Networking Stack: Documentation/networking/index.rst * Filesystems: Documentation/filesystems/index.rst * RCU (Read-Copy Update): Documentation/RCU/index.rst * Locking Primitives: Documentation/locking/index.rst * Power Management: Documentation/power/index.rst Security Expert --------------- Security documentation and hardening guides: * Security Documentation: Documentation/security/index.rst * LSM Development: Documentation/security/lsm-development.rst * Self Protection: Documentation/security/self-protection.rst * Reporting Vulnerabilities: Documentation/process/security-bugs.rst * CVE Procedures: Documentation/process/cve.rst * Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst * Security Features: Documentation/userspace-api/seccomp_filter.rst Backport/Maintenance Engineer ----------------------------- Maintain and stabilize kernel versions: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * Backporting Guide: Documentation/process/backporting.rst * Applying Patches: Documentation/process/applying-patches.rst * Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git for Maintainers: Documentation/maintainer/configure-git.rst System Administrator -------------------- Configure, tune, and troubleshoot Linux systems: * Admin Guide: Documentation/admin-guide/index.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst * Tracing/Debugging: Documentation/trace/index.rst * Performance Security: Documentation/admin-guide/perf-security.rst * Hardware Monitoring: Documentation/hwmon/index.rst Maintainer ---------- Lead kernel subsystems and manage contributions: * Maintainer Handbook: Documentation/maintainer/index.rst * Pull Requests: Documentation/maintainer/pull-requests.rst * Managing Patches: Documentation/maintainer/modifying-patches.rst * Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst * Development Process: Documentation/process/maintainer-handbooks.rst * Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git Configuration: Documentation/maintainer/configure-git.rst Hardware Vendor --------------- Write drivers and support new hardware: * Driver API Guide: Documentation/driver-api/index.rst * Driver Model: Documentation/driver-api/driver-model/driver.rst * Device Drivers: Documentation/driver-api/infrastructure.rst * Bus Types: Documentation/driver-api/driver-model/bus.rst * Device Tree Bindings: Documentation/devicetree/bindings/ * Power Management: Documentation/driver-api/pm/index.rst * DMA API: Documentation/core-api/dma-api.rst Distribution Maintainer ----------------------- Package and distribute the kernel: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * ABI Documentation: Documentation/ABI/README * Kernel Configuration: Documentation/kbuild/kconfig.rst * Module Signing: Documentation/admin-guide/module-signing.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst AI Coding Assistant ------------------- CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and follow the AI coding assistants documentation before contributing to the Linux kernel: * Documentation/process/coding-assistants.rst This documentation contains essential requirements about licensing, attribution, and the Developer Certificate of Origin that all AI tools must comply with. Communication and Support ========================= * Mailing Lists: https://lore.kernel.org/ * IRC: #kernelnewbies on irc.oftc.net * Bugzilla: https://bugzilla.kernel.org/ * MAINTAINERS file: Lists subsystem maintainers and mailing lists * Email Clients: Documentation/process/email-clients.rst