From 64c4dfcd2687461fb915236cc51a3c1b48db383b Mon Sep 17 00:00:00 2001 From: John Baldwin Date: Mon, 13 Apr 2020 20:59:09 +0000 Subject: [PATCH] Export a sysctl count of RX FIFO overrun events. uart(4) backends currently detect RX FIFO overrun errors and report them to the uart(4) core layer. They are then reported to the generic TTY layer which promptly ignores them. As a result, there is currently no good way to determine if a uart is experiencing RX FIFO overruns. One could add a generic per-tty counter, but there did not appear to be a good way to export those. Instead, add a sysctl under the uart(4) sysctl tree to export the count of overruns. Reviewed by: brooks MFC after: 2 weeks Sponsored by: DARPA Differential Revision: https://reviews.freebsd.org/D24368 --- sys/dev/uart/uart_bus.h | 1 + sys/dev/uart/uart_core.c | 7 +++++++ 2 files changed, 8 insertions(+) diff --git a/sys/dev/uart/uart_bus.h b/sys/dev/uart/uart_bus.h index d3b22256b91..5da3cecccf8 100644 --- a/sys/dev/uart/uart_bus.h +++ b/sys/dev/uart/uart_bus.h @@ -111,6 +111,7 @@ struct uart_softc { int sc_rxput; int sc_rxget; int sc_rxfifosz; /* Size of RX FIFO. */ + int sc_rxoverruns; /* Transmitter data. */ uint8_t *sc_txbuf; diff --git a/sys/dev/uart/uart_core.c b/sys/dev/uart/uart_core.c index d664a823f70..89201f3d946 100644 --- a/sys/dev/uart/uart_core.c +++ b/sys/dev/uart/uart_core.c @@ -333,6 +333,7 @@ uart_intr_overrun(void *arg) sc->sc_rxbuf[sc->sc_rxput] = UART_STAT_OVERRUN; uart_sched_softih(sc, SER_INT_RXREADY); } + sc->sc_rxoverruns++; UART_FLUSH(sc, UART_FLUSH_RECEIVER); return (0); } @@ -741,6 +742,12 @@ uart_bus_attach(device_t dev) if (sc->sc_sysdev != NULL) sc->sc_sysdev->hwmtx = sc->sc_hwmtx; + if (sc->sc_rxfifosz > 1) + SYSCTL_ADD_INT(device_get_sysctl_ctx(dev), + SYSCTL_CHILDREN(device_get_sysctl_tree(dev)), OID_AUTO, + "rx_overruns", CTLFLAG_RD, &sc->sc_rxoverruns, 0, + "Receive overruns"); + return (0); fail: