mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-09-18 22:19:30 +02:00
Sergey Zagursky
856c562c94
Since commitc6b1b34b50("media: pci: intel: Add CVS support for IPU bridge driver") the internal camera no longer works on laptops where the sensor sits behind an IVSC, for example a Dell XPS 16 9640 (IPU6, INTC10CF, ov02c10): intel-ipu6 0000:00:05.0: Found supported sensor OVTI02C1:00 intel-ipu6 0000:00:05.0: Connected 1 cameras ivsc_csi intel_vsc-92335fcf-3203-4472-af93-7b4453ac29da: mei-csi probed without device fwnode! No sensor subdevice is registered, the media graph has no sensor entity and userspace finds no camera at all. ipu_bridge_get_ivsc_csi_dev() first looks for the platform device named "intel_vsc" and returns its mei-csi child. That device is created by mei_vsc, which on this machine only appears once the LJCA USB bridge and its SPI controller have probed, about a second after the IPU6 probe that runs the bridge: 07:59:29.297 platform INTC10CF:00 created (ACPI scan) 07:59:41 intel-ipu6 probe -> ipu_bridge_init() 07:59:42.391 platform intel_vsc created (mei_vsc) The commit above added two fallbacks for CVS which match on the ACPI companion alone. They are reached for every entry of ivsc_acpi_ids[], IVSC IDs included. The IVSC ACPI device has two physical nodes: INTC10CF:00/physical_node -> platform/INTC10CF:00 (no driver bound) INTC10CF:00/physical_node1 -> platform/intel_vsc (mei_vsc) so bus_find_device_by_acpi_dev(&platform_bus_type, adev) returns the bare platform device. ipu_bridge_instantiate_ivsc() then attaches the IVSC software node to that device instead of to the mei-csi client, the bridge reports success, and the probe is never retried. mei_csi later probes without a fwnode, the CSI-2 link is never described, and the sensor ACPI device, which has an honoured _DEP on the IVSC device, is never enumerated. Before those fallbacks existed the lookup returned NULL here, the bridge failed with -ENODEV and the probe was retried once the IVSC device had shown up. Skip those fallbacks for IVSC devices, keying on the IVSC IDs rather than the CVS ones: new CVS IDs keep being added, whereas the IVSC list is complete. CVS binds a driver to the ACPI device itself, so matching on the companion stays unambiguous there. Fixes:c6b1b34b50("media: pci: intel: Add CVS support for IPU bridge driver") Link: https://lore.kernel.org/linux-media/20260901194526.6369-1-gvozdoder@gmail.com/ Cc: stable@vger.kernel.org Assisted-by: Claude Code:claude-opus-5 Signed-off-by: Sergey Zagursky <gvozdoder@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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