From 26f073993665683f1debf4d66d8bc274ac6df771 Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Mon, 7 Jan 2019 17:23:19 +0100 Subject: [PATCH] serial: sh-sci: Fix fallback to PIO in sci_dma_rx_complete() When submitting a DMA request fails in sci_dma_rx_complete(), the driver tries to fall back to PIO, but that does not work: no more data will be received, or the kernel will even crash. Fix this similar as in (but not identical to) sci_submit_rx(): - On SCIF, PIO cannot take over if any DMA transactions are pending, hence they must be terminated first. - All active cookies must be invalidated, else rx_timer_fn() may trigger a NULL pointer dereference. - Restarting the port is not needed, as it is already running, but serial port interrupts must be directed back from the DMA engine to the CPU. Signed-off-by: Geert Uytterhoeven Reviewed-by: Simon Horman Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/sh-sci.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c index 4d814c30c418..891833315698 100644 --- a/drivers/tty/serial/sh-sci.c +++ b/drivers/tty/serial/sh-sci.c @@ -1337,8 +1337,9 @@ fail: dev_warn(port->dev, "Failed submitting Rx DMA descriptor\n"); /* Switch to PIO */ spin_lock_irqsave(&port->lock, flags); - s->chan_rx = NULL; - sci_start_rx(port); + dmaengine_terminate_async(chan); + sci_dma_rx_chan_invalidate(s); + sci_dma_rx_reenable_irq(s); spin_unlock_irqrestore(&port->lock, flags); } -- 2.11.0