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serial: 8250_dw: Set maxburst size 

The default burst is often 1 byte which is not very optimal.
The ideal burst size when using 16550A type port would be
1/2 of fifosize, but this does not work with all Designware
implementations. Setting it to 1/4 fifosize.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Heikki Krogerus 2013-01-16 14:08:16 +02:00 committed by Greg Kroah-Hartman
parent 053fac36b1
commit f5836a55de
1 changed files with 4 additions and 2 deletions
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6
drivers/tty/serial/8250/8250_dw.c
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@ -178,6 +178,7 @@ dw8250_acpi_walk_resource(struct acpi_resource *res, void *data)
slave->direction = DMA_MEM_TO_DEV;
slave->dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
slave->slave_id = fixed_dma->request_lines;
slave->dst_maxburst = port->tx_loadsz / 4;
dma->tx_chan_id = fixed_dma->channels;
dma->tx_param = &dma->tx_chan_id;
@ -189,6 +190,7 @@ dw8250_acpi_walk_resource(struct acpi_resource *res, void *data)
slave->direction = DMA_DEV_TO_MEM;
slave->src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
slave->slave_id = fixed_dma->request_lines;
slave->src_maxburst = p->fifosize / 4;
dma->rx_chan_id = fixed_dma->channels;
dma->rx_param = &dma->rx_chan_id;
@ -296,6 +298,8 @@ static int dw8250_probe(struct platform_device *pdev)
uart.port.serial_in = dw8250_serial_in;
uart.port.serial_out = dw8250_serial_out;
dw8250_setup_port(&uart);
if (pdev->dev.of_node) {
err = dw8250_probe_of(&uart.port);
if (err)
@ -308,8 +312,6 @@ static int dw8250_probe(struct platform_device *pdev)
return -ENODEV;
}
dw8250_setup_port(&uart);
data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;