From: Robin Gong <b38343@freescale.com>
Date: Mon, 8 Dec 2014 09:30:40 +0000 (+0800)
Subject: MLK-9768: dma: imx-sdma: fix UART loopback random failed
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=d657e72adc37792f4c1b8b050c6b6ca572aa311c;p=karo-tx-linux.git

MLK-9768: dma: imx-sdma: fix UART loopback random failed

For UART, we need use old chn_real_count to know the real rx count even in
cylic dma mode, because UART driver use cyclic mode to increase performance
without any data loss.

Signed-off-by: Robin Gong <b38343@freescale.com>
---

diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
index 5f97c964efa9..36c0b9294a60 100644
--- a/drivers/dma/imx-sdma.c
+++ b/drivers/dma/imx-sdma.c
@@ -1358,7 +1358,12 @@ static enum dma_status sdma_tx_status(struct dma_chan *chan,
 	struct sdma_channel *sdmac = to_sdma_chan(chan);
 	u32 residue;
 
-	if (sdmac->flags & IMX_DMA_SG_LOOP)
+	/*
+	 * For uart rx data may not receive fully, use old chn_real_count to
+	 * know the real rx count.
+	 */
+	if ((sdmac->flags & IMX_DMA_SG_LOOP) &&
+		(sdmac->peripheral_type != IMX_DMATYPE_UART))
 		residue = (sdmac->num_bd - sdmac->buf_tail) * sdmac->period_len;
 	else
 		residue = sdmac->chn_count - sdmac->chn_real_count;