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serial: samsung: Continue to work if DMA request fails 

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: 62c37eedb7 ("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>
This commit is contained in:
Krzysztof Kozlowski 2017-02-25 18:36:44 +02:00 committed by Greg Kroah-Hartman
parent 82f2341c94
commit f98c7bce57
1 changed files with 4 additions and 2 deletions
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6
drivers/tty/serial/samsung.c
View File

@ -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;
}
}