Re: [PATCH] serial: samsung: Continue to work if DMA request fails
From: Tobias Jakobi <hidden>
Date: 2017-02-25 16:41:34
Also in:
linux-samsung-soc, linux-serial, lkml
Hello Krzysztof, Krzysztof Kozlowski wrote:
quoted hunk ↗ jump to hunk
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=00000000 DMA is not necessary for serial to work, so continue with UART startup after emitting a warning. Fixes: Fixes: 62c37eedb74c ("serial: samsung: add dma reqest/release functions") Cc: <redacted> Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org> --- drivers/tty/serial/samsung.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c index b4f86c219db1..7a17aedbf902 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 =3c24xx_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 =ULL;
This line looks odd. Did you want to assign NULL here? Also, whitespace on both sides of '='? - Tobias
} }