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authorPeter Hurley <peter@hurleysoftware.com>2016-04-09 22:14:32 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-04-30 09:26:55 -0700
commitec5a11a91eecd81ef19b8044a243b4ea56c809e6 (patch)
tree9ddec17e4d8de766912e58be04561eec2d15ee16 /drivers/tty
parent06c5e362ce1fbb29cb9505b4a1191d9489d8bdd2 (diff)
serial: 8250: Validate dmaengine rx chan meets requirements
8250 dma support requires the dmaengine driver support error-free pause/terminate and better-than-descriptor residue granularity. Query slave caps to determine if necessary commands/properties are supported; disable dma if not. Note this means dmaengine driver must support slave caps reporting as well. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
-rw-r--r--drivers/tty/serial/8250/8250_dma.c27
1 files changed, 21 insertions, 6 deletions
diff --git a/drivers/tty/serial/8250/8250_dma.c b/drivers/tty/serial/8250/8250_dma.c
index 78259d3c6a55..cf7a2e3288a6 100644
--- a/drivers/tty/serial/8250/8250_dma.c
+++ b/drivers/tty/serial/8250/8250_dma.c
@@ -158,6 +158,8 @@ int serial8250_request_dma(struct uart_8250_port *p)
{
struct uart_8250_dma *dma = p->dma;
dma_cap_mask_t mask;
+ struct dma_slave_caps caps;
+ int ret;
/* Default slave configuration parameters */
dma->rxconf.direction = DMA_DEV_TO_MEM;
@@ -178,6 +180,16 @@ int serial8250_request_dma(struct uart_8250_port *p)
if (!dma->rxchan)
return -ENODEV;
+ /* 8250 rx dma requires dmaengine driver to support pause/terminate */
+ ret = dma_get_slave_caps(dma->rxchan, &caps);
+ if (ret)
+ goto release_rx;
+ if (!caps.cmd_pause || !caps.cmd_terminate ||
+ caps.residue_granularity == DMA_RESIDUE_GRANULARITY_DESCRIPTOR) {
+ ret = -EINVAL;
+ goto release_rx;
+ }
+
dmaengine_slave_config(dma->rxchan, &dma->rxconf);
/* Get a channel for TX */
@@ -185,8 +197,8 @@ int serial8250_request_dma(struct uart_8250_port *p)
dma->fn, dma->tx_param,
p->port.dev, "tx");
if (!dma->txchan) {
- dma_release_channel(dma->rxchan);
- return -ENODEV;
+ ret = -ENODEV;
+ goto release_rx;
}
dmaengine_slave_config(dma->txchan, &dma->txconf);
@@ -197,8 +209,10 @@ int serial8250_request_dma(struct uart_8250_port *p)
dma->rx_buf = dma_alloc_coherent(dma->rxchan->device->dev, dma->rx_size,
&dma->rx_addr, GFP_KERNEL);
- if (!dma->rx_buf)
+ if (!dma->rx_buf) {
+ ret = -ENOMEM;
goto err;
+ }
/* TX buffer */
dma->tx_addr = dma_map_single(dma->txchan->device->dev,
@@ -208,6 +222,7 @@ int serial8250_request_dma(struct uart_8250_port *p)
if (dma_mapping_error(dma->txchan->device->dev, dma->tx_addr)) {
dma_free_coherent(dma->rxchan->device->dev, dma->rx_size,
dma->rx_buf, dma->rx_addr);
+ ret = -ENOMEM;
goto err;
}
@@ -215,10 +230,10 @@ int serial8250_request_dma(struct uart_8250_port *p)
return 0;
err:
- dma_release_channel(dma->rxchan);
dma_release_channel(dma->txchan);
-
- return -ENOMEM;
+release_rx:
+ dma_release_channel(dma->rxchan);
+ return ret;
}
EXPORT_SYMBOL_GPL(serial8250_request_dma);