freebsd with flexible iflib nic queues
5ea561e03a
Changes to make rtc/cts flow control work... This does not turn on the builtin hardware flow control on the SoC's usart device, because that doesn't work on uart1 due to a chip erratum (they forgot to wire up pin PA21 to RTS0 internally). Instead it uses the hardware flow control logic where the tty layer calls the driver to assert and de-assert the flow control lines as needed. This prevents overruns at the tty layer (app doesn't read fast enough), but does nothing for overruns at the driver layer (interrupts not serviced fast enough). To work around the wiring problem with RTS0, the driver reassigns that pin as a GPIO and controls it manually. It only does so if given permission via hint.uart.1.use_rts0_workaround=1, to prevent accidentally driving the pin if uart1 is used without flow control (because something not related to serial IO could be wired to that pin). In addition to the RTS0 workaround, driver changes were needed in the area of reading the current set of DCE signals. A priming read is now done at attach() time, and the interrupt routine now sets SER_INT_SIGCHG when any of the DCE signals change. Without these changes, nothing could ever be transmitted, because the tty layer thought CTS was de-asserted (when in fact we had just never read the status register, and the hwsig variable was init'd to CTS de-asserted). Changes to support bulk high-speed (230kbps and higher) data reception... Allow the receive fifo size to be tuned with hint.uart.<dev>.fifo_bytes. For high speed receive, a fifo size of 1024 works well. The default is still 128 bytes if no hint is provided. Using a value larger than 384 requires a change in dev/uart/uart_core.c to size the intermediate buffer as MAX(384, 3*sc->sc_rxfifosize). Recalculate the receive timeout whenever the baud rate changes. At low baud rates (19.2kbps and below) the timeout is the number of bits in 2 characters. At higher speed it's calculated to be 500 microseconds worth of bits. The idea is to compromise between being responsive in interactive situations and not timing out prematurely during a brief pause in bulk data flow. The old fixed timeout of 1.5 characters was just 32 microseconds at 460kbps. At interrupt time, check for receiver holding register overrun status and set the corresponding status bit in the return value. When handling a buffer overrun, get a single buffer emptied and handed back to the hardware as quickly as possible, then deal with the second buffer. This at least minimizes data loss compared to the old logic that fully processed both buffers before restarting the hardware. Rewrite the logic for handling buffers after a receive timeout. The original author speculated in a comment that there may be a race with high speed data. There was, although it was rare. The code now handles all three possible scenarios on receive timeout: two empty buffers, one empty and one partial buffer, or one full and one partial buffer. Reviewed by: imp |
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| bin | ||
| cddl | ||
| contrib | ||
| crypto | ||
| etc | ||
| games | ||
| gnu | ||
| include | ||
| kerberos5 | ||
| lib | ||
| libexec | ||
| release | ||
| rescue | ||
| sbin | ||
| secure | ||
| share | ||
| sys | ||
| tools | ||
| usr.bin | ||
| usr.sbin | ||
| COPYRIGHT | ||
| LOCKS | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc1 | ||
| ObsoleteFiles.inc | ||
| README | ||
| UPDATING | ||
This is the top level of the FreeBSD source directory. This file was last revised on: $FreeBSD$ For copyright information, please see the file COPYRIGHT in this directory (additional copyright information also exists for some sources in this tree - please see the specific source directories for more information). The Makefile in this directory supports a number of targets for building components (or all) of the FreeBSD source tree, the most commonly used one being ``world'', which rebuilds and installs everything in the FreeBSD system from the source tree except the kernel, the kernel-modules and the contents of /etc. The ``world'' target should only be used in cases where the source tree has not changed from the currently running version. See: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html for more information, including setting make(1) variables. The ``buildkernel'' and ``installkernel'' targets build and install the kernel and the modules (see below). Please see the top of the Makefile in this directory for more information on the standard build targets and compile-time flags. Building a kernel is a somewhat more involved process, documentation for which can be found at: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html And in the config(8) man page. Note: If you want to build and install the kernel with the ``buildkernel'' and ``installkernel'' targets, you might need to build world before. More information is available in the handbook. The sample kernel configuration files reside in the sys/<arch>/conf sub-directory (assuming that you've installed the kernel sources), the file named GENERIC being the one used to build your initial installation kernel. The file NOTES contains entries and documentation for all possible devices, not just those commonly used. It is the successor of the ancient LINT file, but in contrast to LINT, it is not buildable as a kernel but a pure reference and documentation file. Source Roadmap: --------------- bin System/user commands. cddl Various commands and libraries under the Common Development and Distribution License. contrib Packages contributed by 3rd parties. crypto Cryptography stuff (see crypto/README). etc Template files for /etc. games Amusements. gnu Various commands and libraries under the GNU Public License. Please see gnu/COPYING* for more information. include System include files. kerberos5 Kerberos5 (Heimdal) package. lib System libraries. libexec System daemons. release Release building Makefile & associated tools. rescue Build system for statically linked /rescue utilities. sbin System commands. secure Cryptographic libraries and commands. share Shared resources. sys Kernel sources. tools Utilities for regression testing and miscellaneous tasks. usr.bin User commands. usr.sbin System administration commands. For information on synchronizing your source tree with one or more of the FreeBSD Project's development branches, please see: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/synching.html