serial: samsung: Continue to work if DMA request fails

krzk · gregkh · commit f98c7bce570b · 2017-03-07T19:58:37.000+01:00
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: 62c37ee ("serial: samsung: add dma reqest/release functions") Cc: <stable@vger.kernel.org> Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git 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;
 		}
 	}
 

Original file line number	Diff line number	Diff line change
`@@ -1031,8 +1031,10 @@ static int s3c64xx_serial_startup(struct uart_port *port)`
`1031`	`1031`	`if (ourport->dma) {`
`1032`	`1032`	`ret = s3c24xx_serial_request_dma(ourport);`
`1033`	`1033`	`if (ret < 0) {`
`1034`		`- dev_warn(port->dev, "DMA request failed\n");`
`1035`		`- return ret;`
	`1034`	`+ dev_warn(port->dev,`
	`1035`	`+ "DMA request failed, DMA will not be used\n");`
	`1036`	`+ devm_kfree(port->dev, ourport->dma);`
	`1037`	`+ ourport->dma = NULL;`
`1036`	`1038`	`}`
`1037`	`1039`	`}`
`1038`	`1040`