From: Andrew Jackson <Andrew.Jackson@arm.com>
Date: Fri, 7 Nov 2014 14:14:39 +0000 (+0000)
Subject: serial: pl011: Avoid assumptions about buffer size when refilling TX DMA
X-Git-Tag: firefly_0821_release~176^2~2678^2~44
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=e2a545a6aee935e44db08797f7155be38f3c18f9;p=firefly-linux-kernel-4.4.55.git

serial: pl011: Avoid assumptions about buffer size when refilling TX DMA

The existing code assumed that PL011_DMA_BUFFER_SIZE == UART_XMIT_SIZE,
which may not always be the case.  This allows for these two being
different sizes and not copying too much data.

Signed-off-by: Andrew Jackson <Andrew.Jackson@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 8654049a70c0..6153a42d68db 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -501,7 +501,11 @@ static int pl011_dma_tx_refill(struct uart_amba_port *uap)
 		memcpy(&dmatx->buf[0], &xmit->buf[xmit->tail], count);
 	else {
 		size_t first = UART_XMIT_SIZE - xmit->tail;
-		size_t second = xmit->head;
+		size_t second;
+
+		if (first > count)
+			first = count;
+		second = count - first;
 
 		memcpy(&dmatx->buf[0], &xmit->buf[xmit->tail], first);
 		if (second)