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Export a sysctl count of RX FIFO overrun events.

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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
This commit is contained in:
John Baldwin 2020-04-13 20:59:09 +00:00
parent b47c1eda0c
commit 64c4dfcd26
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=359900
2 changed files with 8 additions and 0 deletions
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1
sys/dev/uart/uart_bus.h
View File

@ -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;

7
sys/dev/uart/uart_core.c
View File

@ -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: