tty: serial: pch: don't crash if DMA enabled but not loaded
authorSebastian Andrzej Siewior <bigeasy@linutronix.de>
Wed, 4 Dec 2013 19:52:49 +0000 (20:52 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Mon, 9 Dec 2013 01:16:05 +0000 (17:16 -0800)
if the DMA driver isn't loaded "on time" then we crash in the irq handler:
| pch_uart 0000:02:0a.4: pch_request_dma:dma_request_channel FAILS(Tx)
| BUG: unable to handle kernel NULL pointer dereference at   (null)
| IP: [<c0676ed9>] pch_uart_interrupt+0x739/0x940

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/tty/serial/pch_uart.c

Simple merge