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path: root/drivers/tty/serial/samsung.c
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Diffstat (limited to 'drivers/tty/serial/samsung.c')
-rw-r--r--drivers/tty/serial/samsung.c40
1 files changed, 31 insertions, 9 deletions
diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
index 3f2f8c118ce0..2f8fa184aafa 100644
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -856,35 +856,54 @@ static void s3c24xx_serial_break_ctl(struct uart_port *port, int break_state)
static int s3c24xx_serial_request_dma(struct s3c24xx_uart_port *p)
{
struct s3c24xx_uart_dma *dma = p->dma;
+ struct dma_slave_caps dma_caps;
+ const char *reason = NULL;
int ret;
/* Default slave configuration parameters */
dma->rx_conf.direction = DMA_DEV_TO_MEM;
dma->rx_conf.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
dma->rx_conf.src_addr = p->port.mapbase + S3C2410_URXH;
- dma->rx_conf.src_maxburst = 16;
+ dma->rx_conf.src_maxburst = 1;
dma->tx_conf.direction = DMA_MEM_TO_DEV;
dma->tx_conf.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
dma->tx_conf.dst_addr = p->port.mapbase + S3C2410_UTXH;
- if (dma_get_cache_alignment() >= 16)
- dma->tx_conf.dst_maxburst = 16;
- else
- dma->tx_conf.dst_maxburst = 1;
+ dma->tx_conf.dst_maxburst = 1;
dma->rx_chan = dma_request_chan(p->port.dev, "rx");
- if (IS_ERR(dma->rx_chan))
- return PTR_ERR(dma->rx_chan);
+ if (IS_ERR(dma->rx_chan)) {
+ reason = "DMA RX channel request failed";
+ ret = PTR_ERR(dma->rx_chan);
+ goto err_warn;
+ }
+
+ ret = dma_get_slave_caps(dma->rx_chan, &dma_caps);
+ if (ret < 0 ||
+ dma_caps.residue_granularity < DMA_RESIDUE_GRANULARITY_BURST) {
+ reason = "insufficient DMA RX engine capabilities";
+ ret = -EOPNOTSUPP;
+ goto err_release_rx;
+ }
dmaengine_slave_config(dma->rx_chan, &dma->rx_conf);
dma->tx_chan = dma_request_chan(p->port.dev, "tx");
if (IS_ERR(dma->tx_chan)) {
+ reason = "DMA TX channel request failed";
ret = PTR_ERR(dma->tx_chan);
goto err_release_rx;
}
+ ret = dma_get_slave_caps(dma->tx_chan, &dma_caps);
+ if (ret < 0 ||
+ dma_caps.residue_granularity < DMA_RESIDUE_GRANULARITY_BURST) {
+ reason = "insufficient DMA TX engine capabilities";
+ ret = -EOPNOTSUPP;
+ goto err_release_tx;
+ }
+
dmaengine_slave_config(dma->tx_chan, &dma->tx_conf);
/* RX buffer */
@@ -899,6 +918,7 @@ static int s3c24xx_serial_request_dma(struct s3c24xx_uart_port *p)
dma->rx_addr = dma_map_single(p->port.dev, dma->rx_buf,
dma->rx_size, DMA_FROM_DEVICE);
if (dma_mapping_error(p->port.dev, dma->rx_addr)) {
+ reason = "DMA mapping error for RX buffer";
ret = -EIO;
goto err_free_rx;
}
@@ -907,6 +927,7 @@ static int s3c24xx_serial_request_dma(struct s3c24xx_uart_port *p)
dma->tx_addr = dma_map_single(p->port.dev, p->port.state->xmit.buf,
UART_XMIT_SIZE, DMA_TO_DEVICE);
if (dma_mapping_error(p->port.dev, dma->tx_addr)) {
+ reason = "DMA mapping error for TX buffer";
ret = -EIO;
goto err_unmap_rx;
}
@@ -922,6 +943,9 @@ err_release_tx:
dma_release_channel(dma->tx_chan);
err_release_rx:
dma_release_channel(dma->rx_chan);
+err_warn:
+ if (reason)
+ dev_warn(p->port.dev, "%s, DMA will not be used\n", reason);
return ret;
}
@@ -1040,8 +1064,6 @@ static int s3c64xx_serial_startup(struct uart_port *port)
if (ourport->dma) {
ret = s3c24xx_serial_request_dma(ourport);
if (ret < 0) {
- dev_warn(port->dev,
- "DMA request failed, DMA will not be used\n");
devm_kfree(port->dev, ourport->dma);
ourport->dma = NULL;
}