[PATCH 01/10] dma: imx-sdma: use chn_real_count to report residue for UART

[Jiada Wang]

For uart rx dma data may not receive fully, so the number
of data read by sdma script once isn't always equal to period_len,
thus residue returned from sdma_tx_status() isn't valid for uart rx
dma. The old way to use chn_real_count to report residue should be
used for uart rx dma.

Signed-off-by: Jiada Wang <jiada_w...@mentor.com>
---
 drivers/dma/imx-sdma.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
index 0f6fd42..1f1b64b 100644
--- a/drivers/dma/imx-sdma.c
+++ b/drivers/dma/imx-sdma.c
@@ -680,6 +680,11 @@ static void sdma_update_channel_loop(struct sdma_channel 
*sdmac)
                bd->mode.status |= BD_DONE;
                sdmac->buf_tail++;
                sdmac->buf_tail %= sdmac->num_bd;
+               if (sdmac->peripheral_type == IMX_DMATYPE_UART) {
+                       /* restore mode.count after counter readed */
+                       sdmac->chn_real_count = bd->mode.count;
+                       bd->mode.count = sdmac->chn_count;
+               }
        }
 }
 
@@ -1285,6 +1290,9 @@ static struct dma_async_tx_descriptor 
*sdma_prep_dma_cyclic(
                goto err_out;
        }
 
+       if (sdmac->peripheral_type == IMX_DMATYPE_UART)
+               sdmac->chn_count = period_len;
+
        while (buf < buf_len) {
                struct sdma_buffer_descriptor *bd = &sdmac->bd[i];
                int param;
@@ -1361,7 +1369,8 @@ 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)
+       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;
-- 
2.4.5