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Our tests with the I2C bit clear mechanism (recovering from "lost arbitration" errors) show that the bit clear hardware does not work correctly in some situations. When a wedged slave device tries to send more than one 0-to-1-to-0 transition to the host (e.g. leftover bits from an aborted read), the controller never transitions the BC_ENABLE bit back to zero. This patch adds a long timeout to the bit clear code that waits for register transitions as a safeguard. This way, We will still eventually exit the function (probably followed by a reboot). Our tests show that this will recover from all conditions after at most a few reboots. BRANCH=nyan BUG=chrome-os-partner:28323 TEST=Ran wedge_ack and wedge_read tests with software_i2c patch, system recovered as expected in all cases. Original-Change-Id: I6c37119130e1240e1ef3a5944582abbcd2e39ff0 Original-Signed-off-by: Julius Werner <jwerner@chromium.org> Original-Reviewed-on: https://chromium-review.googlesource.com/200265 Original-Reviewed-by: Tom Warren <twarren@nvidia.com> Original-Reviewed-by: Gabe Black <gabeblack@chromium.org> (cherry picked from commit 4c8d0af25cf107a38c856b38067b8f2f74384f22) Signed-off-by: Marc Jones <marc.jones@se-eng.com> Change-Id: I600d5c9a8e68719cf8795c083c5fac63f626f5bf Reviewed-on: http://review.coreboot.org/7948 Tested-by: build bot (Jenkins) Reviewed-by: David Hendricks <dhendrix@chromium.org>
------------------------------------------------------------------------------- coreboot README ------------------------------------------------------------------------------- coreboot is a Free Software project aimed at replacing the proprietary BIOS (firmware) found in most computers. coreboot performs a little bit of hardware initialization and then executes additional boot logic, called a payload. With the separation of hardware initialization and later boot logic, coreboot can scale from specialized applications that run directly firmware, run operating systems in flash, load custom bootloaders, or implement firmware standards, like PC BIOS services or UEFI. This allows for systems to only include the features necessary in the target application, reducing the amount of code and flash space required. coreboot was formerly known as LinuxBIOS. Payloads -------- After the basic initialization of the hardware has been performed, any desired "payload" can be started by coreboot. See http://www.coreboot.org/Payloads for a list of supported payloads. Supported Hardware ------------------ coreboot supports a wide range of chipsets, devices, and mainboards. For details please consult: * http://www.coreboot.org/Supported_Motherboards * http://www.coreboot.org/Supported_Chipsets_and_Devices Build Requirements ------------------ * gcc / g++ * make Optional: * doxygen (for generating/viewing documentation) * iasl (for targets with ACPI support) * gdb (for better debugging facilities on some targets) * ncurses (for 'make menuconfig') * flex and bison (for regenerating parsers) Building coreboot ----------------- Please consult http://www.coreboot.org/Build_HOWTO for details. Testing coreboot Without Modifying Your Hardware ------------------------------------------------ If you want to test coreboot without any risks before you really decide to use it on your hardware, you can use the QEMU system emulator to run coreboot virtually in QEMU. Please see http://www.coreboot.org/QEMU for details. Website and Mailing List ------------------------ Further details on the project, a FAQ, many HOWTOs, news, development guidelines and more can be found on the coreboot website: http://www.coreboot.org You can contact us directly on the coreboot mailing list: http://www.coreboot.org/Mailinglist Copyright and License --------------------- The copyright on coreboot is owned by quite a large number of individual developers and companies. Please check the individual source files for details. coreboot is licensed under the terms of the GNU General Public License (GPL). Some files are licensed under the "GPL (version 2, or any later version)", and some files are licensed under the "GPL, version 2". For some parts, which were derived from other projects, other (GPL-compatible) licenses may apply. Please check the individual source files for details. This makes the resulting coreboot images licensed under the GPL, version 2.