mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/
synced 2026-11-10 20:48:12 +00:00
No description
- C 96.8%
- Assembly 0.9%
- Rust 0.7%
- Shell 0.6%
- Python 0.5%
- Other 0.3%
fd99864b0a
Most SPI NOR chips today use 0x05 as ReaD Status Register (RDSR) opcode. After almost every transaction, the core will wait for the said transation to be digested by the chip by polling its status register. This mechanism has been automated by certain chips, such as the Cadence QSPI controller. Unfortunately, the feature has been disabled for various (relevant) reasons. Disabling this feature has been done by setting WRITE_COMPLETION_CTRL_REG.DISABLE_POLLING_FLD, keeping the rest of the register intact. In this same register, there is also a field named WRITE_COMPLETION_CTRL_REG.OPCODE_FLD, which by default also contains 0x05, as primary RDSR opcode. As a result, both the SPI NOR and SPI NAND cores, primary users through spi-mem of the spi_mem_ops interface, do send their own RDSR. In this driver, such command goes through one of the fifth possible data path specifically crafted for short register-like commands, named STIG. In STIG mode, the opcode of the operation is written to OSPI_FLASH_CMD_CTRL_REG. This means that the opcode field of STIG configuration and the opcode field of the automatic polling configuration contain the same value. Unfortunately, the TRM explains in two different places that this configuration is forbidden, without explaining why it is problematic: $12.4.2.4.11 OSPI Software-Triggered Instruction Generator (STIG) ``` OSPI_FLASH_CMD_CTRL_REG[31-24] CMD_OPCODE_FLD bits should be set different than OSPI_DEV_INSTR_RD_CONFIG_REG[7-0] RD_OPCODE_NON_XIP_FLD and OSPI_DEV_INSTR_WR_CONFIG_REG[7-0] WR_OPCODE_FLD. ``` and $12.4.2.5.2 Configuring the OSPI Controller for Optimal Use ``` When using the OSPI Controller, the opcodes in OSPI_DEV_INSTR_RD_CONFIG_REG[7-0] RD_OPCODE_NON_XIP_FLD, OSPI_DEV_INSTR_WR_CONFIG_REG[7-0] WR_OPCODE_FLD and OSPI_WRITE_COMPLETION_CTRL_REG[7-0] OPCODE_FLD bit fields shall not match the opcode in the OSPI_FLASH_CMD_CTRL_REG[31-24] CMD_OPCODE_FLD bit field. ``` For some reasons, this is only unveiled now when testing in ODTR mode. Plain SDR modes work flawlessly with the same chips. One possible reason for this, is that the internal data path in ODTR mode is very different due to the extra opcode extension/repetition which may be interpreted differently (this is a wild guess). For sure there is an interference, as even the TRM states that there is some magic happening: $12.4.2.4.13 OSPI Command Translation ``` The WREN and the RDSR device instructions are the only ones that are sent by the controller under the hood. ``` I cannot probe the bus when the problem arises, so I don't know exactly what is sent on the bus. Practically speaking, the chip was driving the lines low (reading all 0s), which is not the usual default state when the chip is not driving the lines (all 1s). Other people on the mailing list claimed successfully using ODTR chips with this controller. My take here is that either they were using a variant of the IP without write completion at all (there is a quirk for it), or they were using chips slightly more flexible about their opcode sequency or maybe with different addr/dummy requirements. Clearing the WRITE_COMPLETION_CTRL_REG.OPCODE_FLD while disabling write completion polling entirely seems the best compromise. Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> Link: https://patch.msgid.link/20261001-winbond-spi-next-cadence-rdsr-fix-v1-1-ec5ff594ba5d@bootlin.com Signed-off-by: Mark Brown <broonie@kernel.org> |
History
|
|
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .pylintrc | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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