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@xxxxxxxxx>
---
v4:
- No changes,
v3:
- Add missing definition of "u16 scr",
- Move call to dmaengine_terminate_async() inside the spinlock, for
symmetry with sci_submit_rx(),
- Split in multiple patches.
---
drivers/tty/serial/sh-sci.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 8df0fd8245203f8b..44c29ce3fcc5d894 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1272,6 +1272,8 @@ static void sci_dma_rx_complete(void *arg)
struct dma_async_tx_descriptor *desc;
unsigned long flags;
int active, count = 0;
+ unsigned int i;
+ u16 scr;
dev_dbg(port->dev, "%s(%d) active cookie %d\n", __func__, port->line,
s->active_rx);
@@ -1313,8 +1315,18 @@ 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);
+ dmaengine_terminate_async(chan);
+ for (i = 0; i < 2; i++)
+ s->cookie_rx[i] = -EINVAL;
+ s->active_rx = 0;
s->chan_rx = NULL;
- sci_start_rx(port);
+ /* Direct new serial port interrupts back to CPU */
+ scr = serial_port_in(port, SCSCR);
+ if (port->type == PORT_SCIFA || port->type == PORT_SCIFB) {
+ scr &= ~SCSCR_RDRQE;
+ enable_irq(s->irqs[SCIx_RXI_IRQ]);
+ }
+ serial_port_out(port, SCSCR, scr | SCSCR_RIE);
spin_unlock_irqrestore(&port->lock, flags);
}
--
2.17.1
