diff mbox

serial: 8250_dw: Add DMA support for non-ACPI platforms

Message ID 1412728547-4126-1-git-send-email-rjui@broadcom.com
State Accepted
Commit a8b26e1af94825296f29eee6bfc001c5543d3c7e
Headers show

Commit Message

Ray Jui Oct. 8, 2014, 12:35 a.m. UTC 
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 <rjui@broadcom.com>
Reviewed-by: JD (Jiandong) Zheng <jdzheng@broadcom.com>
Reviewed-by: Scott Branden <sbranden@broadcom.com>
Tested-by: Scott Branden <sbranden@broadcom.com>
---
 drivers/tty/serial/8250/8250_dw.c |    8 ++++++++
 1 file changed, 8 insertions(+)

Comments

Heikki Krogerus Oct. 9, 2014, 1:20 p.m. UTC | #1 
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 <rjui@broadcom.com>
> Reviewed-by: JD (Jiandong) Zheng <jdzheng@broadcom.com>
> Reviewed-by: Scott Branden <sbranden@broadcom.com>
> Tested-by: Scott Branden <sbranden@broadcom.com>

OK by me. FWIW..

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
diff mbox

Patch

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;