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Fix grabbing of tegra uart.

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An attempt to write to FCR register may corrupt transmit FIFO,
so we should wait for the FIFO to be empty before we can modify it.

MFC after:	1 week
This commit is contained in:
mmel 2020-06-11 12:53:22 +00:00
parent 993de18d60
commit db1597c8a7
1 changed files with 4 additions and 0 deletions
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4
sys/arm/nvidia/tegra_uart.c
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@ -102,6 +102,10 @@ tegra_uart_grab(struct uart_softc *sc)
uart_lock(sc->sc_hwmtx);
ier = uart_getreg(bas, REG_IER);
uart_setreg(bas, REG_IER, ier & ns8250->ier_mask);
while ((uart_getreg(bas, REG_LSR) & LSR_TEMT) == 0)
;
uart_setreg(bas, REG_FCR, 0);
uart_barrier(bas);
uart_unlock(sc->sc_hwmtx);