No description
83da50173c
The current XHCI code only sets IOC on the last TRB of a TD, and doesn't set ISP anywhere. On my Synopsys DesignWare3 controller, this won't generate an event at all when we have a short transfer that is not on the last TRB of a TD, resulting in event ring desync and everyone having a bad time. However, just setting ISP on other TRBs doesn't really make for a nice solution: we then need to do ugly special casing to fish out the spurious second transfer event you get for short packets, and we still need a way to figure out how many bytes were transferred. Since the Short Packet transfer event only reports untransferred bytes for the current TRB, we would have to manually walk the rest of the unprocessed TRB chain and add up the bytes. Check out U-Boot and the Linux kernel to see how complicated this looks in practice. Now what if we had a way to just tell the HC "I want an event at exactly *this* point in the TD, I want it to have the right completion code for the whole TD, and to contain the exact number of bytes written"? Enter the Event Data TRB: this little gizmo really does pretty much exactly what any sane XHCI driver would want, and I have no idea why it isn't used more often. It solves both the short packet event generation and counting the transferred bytes without requiring any special magic in software. Change-Id: Idab412d61edf30655ec69c80066bfffd80290403 Signed-off-by: Julius Werner <jwerner@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/170980 Reviewed-by: Stefan Reinauer <reinauer@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> (cherry picked from commit e512c8bcaa5b8e05cae3b9d04cd4947298de999d) Signed-off-by: Isaac Christensen <isaac.christensen@se-eng.com> Reviewed-on: http://review.coreboot.org/6516 Tested-by: build bot (Jenkins) Reviewed-by: Ronald G. Minnich <rminnich@gmail.com> |
||
|---|---|---|
| 3rdparty@45f0c04fd7 | ||
| documentation | ||
| payloads | ||
| src | ||
| util | ||
| .gitignore | ||
| .gitmodules | ||
| .gitreview | ||
| COPYING | ||
| Makefile | ||
| Makefile.inc | ||
| README | ||
| toolchain.inc | ||
------------------------------------------------------------------------------- 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.