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Commit ec5a11a9 authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman
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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: default avatarPeter Hurley <peter@hurleysoftware.com>
Reviewed-by: default avatarHeikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 06c5e362

drivers/tty/serial/8250/8250_dma.c

+21 −6
Original line number Diff line number Diff line
@@ -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);