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serial: sh-sci: Fix fallback to PIO in sci_dma_rx_complete()

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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 <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Geert Uytterhoeven
2019-01-07 17:23:19 +01:00
committed by Greg Kroah-Hartman
parent 38766e4b61
commit 26f0739936
1 changed files with 3 additions and 2 deletions
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5
drivers/tty/serial/sh-sci.c
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@@ -1337,8 +1337,9 @@ static void sci_dma_rx_complete(void *arg)
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);
}