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ArmPlatformPkg: detect correct pl011 fifo depth

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pl011 releases earlier than r1p5 has a fifo depth of 16 bytes, whereas
version r1p5 upwards has a fifo depth of 32 bytes. The pl011 driver was
hardwired to 32 byte depth, causing dropped characters on some platforms
(including default settings on FVP Base and Foundation models).
Update driver to select 16 or 32 on port initialization by checking the
component revision.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
Reviewed-by: Olivier Martin <olivier.martin@arm.com>



git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16656 6f19259b-4bc3-4df7-8a09-765794883524
This commit is contained in:
Leif Lindholm
2015-01-23 16:10:00 +00:00
committed by oliviermartin
parent ac83357a43
commit 48edf6be7f
2 changed files with 13 additions and 2 deletions
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7
ArmPlatformPkg/Drivers/PL011Uart/PL011Uart.c
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@@ -50,12 +50,15 @@ PL011UartInitializePort (
LineControl = 0;
// The PL011 supports a buffer of either 1 or 32 chars. Therefore we can accept
// The PL011 supports a buffer of 1, 16 or 32 chars. Therefore we can accept
// 1 char buffer as the minimum fifo size. Because everything can be rounded down,
// there is no maximum fifo size.
if ((*ReceiveFifoDepth == 0) || (*ReceiveFifoDepth >= 32)) {
LineControl |= PL011_UARTLCR_H_FEN;
*ReceiveFifoDepth = 32;
if (PL011_UARTPID2_VER (MmioRead32 (UartBase + UARTPID2)) > PL011_VER_R1P4)
*ReceiveFifoDepth = 32;
else
*ReceiveFifoDepth = 16;
} else {
ASSERT (*ReceiveFifoDepth < 32);
// Nothing else to do. 1 byte fifo is default.