2014-10-08 00:35:13

by Ray Jui

Subject: [PATCH] serial: 8250_dw: Add DMA support for non-ACPI platforms

The dma pointer under struct uart_8250_port is currently left
unassigned for non-ACPI platforms. It should be pointing to the dma
member in struct dw8250_data like how it was done for ACPI, so the core
8250 code will try to request for DMA when registering the port

If DMA is not enabled in device tree, request DMA will fail and the
driver will fall back to PIO

Signed-off-by: Ray Jui <[email protected]>
Reviewed-by: JD (Jiandong) Zheng <[email protected]>
Reviewed-by: Scott Branden <[email protected]>
Tested-by: Scott Branden <[email protected]>
---
drivers/tty/serial/8250/8250_dw.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index 4db7987..1038ea8 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -293,6 +293,14 @@ static int dw8250_probe_of(struct uart_port *p,
if (has_ucv)
dw8250_setup_port(up);

+ /* if we have a valid fifosize, try hooking up DMA here */
+ if (p->fifosize) {
+ up->dma = &data->dma;
+
+ up->dma->rxconf.src_maxburst = p->fifosize / 4;
+ up->dma->txconf.dst_maxburst = p->fifosize / 4;
+ }
+
if (!of_property_read_u32(np, "reg-shift", &val))
p->regshift = val;

--
1.7.9.5

2014-10-09 13:20:57

by Heikki Krogerus

Subject: Re: [PATCH] serial: 8250_dw: Add DMA support for non-ACPI platforms

On Tue, Oct 07, 2014 at 05:35:47PM -0700, Ray Jui wrote:
> The dma pointer under struct uart_8250_port is currently left
> unassigned for non-ACPI platforms. It should be pointing to the dma
> member in struct dw8250_data like how it was done for ACPI, so the core
> 8250 code will try to request for DMA when registering the port
>
> If DMA is not enabled in device tree, request DMA will fail and the
> driver will fall back to PIO
>
> Signed-off-by: Ray Jui <[email protected]>
> Reviewed-by: JD (Jiandong) Zheng <[email protected]>
> Reviewed-by: Scott Branden <[email protected]>
> Tested-by: Scott Branden <[email protected]>

OK by me. FWIW..

Reviewed-by: Heikki Krogerus <[email protected]>


--
heikki