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Subject[PATCH 4.20 183/352] serial: sh-sci: Resume PIO in sci_rx_interrupt() on DMA failure
Date
4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 71ab1c0336c71ace5725740f200beca9667a339f ]

On (H)SCIF, sci_submit_rx() is called in the receive interrupt handler.
Hence if DMA submission fails, the interrupt handler should resume
handling reception using PIO, else no more data is received.

Make sci_submit_rx() return an error indicator, so the receive interrupt
handler can act appropriately.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tty/serial/sh-sci.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 613007d7165e..21fd3f6ad28e 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1331,7 +1331,7 @@ static void sci_tx_dma_release(struct sci_port *s)
dma_release_channel(chan);
}

-static void sci_submit_rx(struct sci_port *s, bool port_lock_held)
+static int sci_submit_rx(struct sci_port *s, bool port_lock_held)
{
struct dma_chan *chan = s->chan_rx;
struct uart_port *port = &s->port;
@@ -1359,7 +1359,7 @@ static void sci_submit_rx(struct sci_port *s, bool port_lock_held)
s->active_rx = s->cookie_rx[0];

dma_async_issue_pending(chan);
- return;
+ return 0;

fail:
/* Switch to PIO */
@@ -1374,6 +1374,7 @@ fail:
sci_start_rx(port);
if (!port_lock_held)
spin_unlock_irqrestore(&port->lock, flags);
+ return -EAGAIN;
}

static void work_fn_tx(struct work_struct *work)
@@ -1668,8 +1669,10 @@ static irqreturn_t sci_rx_interrupt(int irq, void *ptr)
disable_irq_nosync(irq);
scr |= SCSCR_RDRQE;
} else {
+ if (sci_submit_rx(s, false) < 0)
+ goto handle_pio;
+
scr &= ~SCSCR_RIE;
- sci_submit_rx(s, false);
}
serial_port_out(port, SCSCR, scr);
/* Clear current interrupt */
@@ -1681,6 +1684,8 @@ static irqreturn_t sci_rx_interrupt(int irq, void *ptr)

return IRQ_HANDLED;
}
+
+handle_pio:
#endif

if (s->rx_trigger > 1 && s->rx_fifo_timeout > 0) {
--
2.19.1


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