Date: Sun, 31 Mar 2013 23:24:04 +0000 (UTC) From: Ian Lepore <ian@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r248963 - head/sys/dev/uart Message-ID: <201303312324.r2VNO4Xd030736@svn.freebsd.org>
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Author: ian Date: Sun Mar 31 23:24:04 2013 New Revision: 248963 URL: http://svnweb.freebsd.org/changeset/base/248963 Log: Accommodate uart devices with large FIFOs (or DMA buffers which amount 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. Modified: head/sys/dev/uart/uart_core.c Modified: head/sys/dev/uart/uart_core.c ============================================================================== --- head/sys/dev/uart/uart_core.c Sun Mar 31 22:43:16 2013 (r248962) +++ head/sys/dev/uart/uart_core.c Sun Mar 31 23:24:04 2013 (r248963) @@ -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),
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