serial: samsung: Continue to work if DMA request fails

f98c7bce · Krzysztof Kozlowski <[email protected]> · 2017-02-25 18:36:44 +02:00

If DMA is not available (even when configured in DeviceTree), the driver
will fail the startup procedure thus making serial console not
available.

For example this causes boot failure on QEMU ARMv7 (Exynos4210, SMDKC210):
    [    1.302575] OF: amba_device_add() failed (-19) for /amba/pdma@12680000
    ...
    [   11.435732] samsung-uart 13800000.serial: DMA request failed
    [   72.963893] samsung-uart 13800000.serial: DMA request failed
    [   73.143361] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000000

DMA is not necessary for serial to work, so continue with UART startup
after emitting a warning.

Fixes: 62c37eedb74c ("serial: samsung: add dma reqest/release functions")
Cc: <[email protected]>
Signed-off-by: Krzysztof Kozlowski <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Commit: f98c7bce570bdbe344b74ff5daa7dfeef3f22929
Parents: 82f2341c

Changes

1 files changed · +4 −2

File	Status	Add	Del	Content
drivers/tty/serial/samsung.c	modified	+4	−2	View file

drivers/tty/serial/samsung.c

View file

diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
index b4f86c2..7a17aed 100644
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -1031,8 +1031,10 @@ static int s3c64xx_serial_startup(struct uart_port *port)
 	if (ourport->dma) {
 		ret = s3c24xx_serial_request_dma(ourport);
 		if (ret < 0) {
-			dev_warn(port->dev, "DMA request failed\n");
-			return ret;
+			dev_warn(port->dev,
+				 "DMA request failed, DMA will not be used\n");
+			devm_kfree(port->dev, ourport->dma);
+			ourport->dma = NULL;
 		}
 	}
 