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Accommodate uart devices with large FIFOs (or DMA buffers which amount

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to the same thing) by allocating the uart(4) rx buffer based on the
device's rxfifosz rather than using a hard-coded size of 384 bytes.

The  historical 384 byte size is 3 times the largest hard-coded fifo
size in the tree, so use that ratio as a guide and allocate the buffer
as three times rxfifosz, but never smaller than the historical size.
This commit is contained in:
Ian Lepore 2013-03-31 23:24:04 +00:00
parent 6fb87f7371
commit 3ad36a413d
1 changed files with 7 additions and 1 deletions
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8
sys/dev/uart/uart_core.c
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@ -457,7 +457,13 @@ uart_bus_attach(device_t dev)
callout_init(&sc->sc_timer, 1);
}
sc->sc_rxbufsz = 384;
/*
* Ensure there is room for at least three full FIFOs of data in the
* receive buffer (handles the case of low-level drivers with huge
* FIFOs), and also ensure that there is no less than the historical
* size of 384 bytes (handles the typical small-FIFO case).
*/
sc->sc_rxbufsz = MAX(384, sc->sc_rxfifosz * 3);
sc->sc_rxbuf = malloc(sc->sc_rxbufsz * sizeof(*sc->sc_rxbuf),
M_UART, M_WAITOK);
sc->sc_txbuf = malloc(sc->sc_txfifosz * sizeof(*sc->sc_txbuf),