From: Geert Uytterhoeven <geert+renesas@glider.be>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jslaby@suse.com>
Cc: Ulrich Hecht <uli+renesas@fpond.eu>,
Wolfram Sang <wsa+renesas@sang-engineering.com>,
Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
linux-renesas-soc@vger.kernel.org, linux-sh@vger.kernel.org,
linux-serial@vger.kernel.org,
Geert Uytterhoeven <geert+renesas@glider.be>
Subject: [PATCH v4 4/4] serial: sh-sci: Fix fallback to PIO in sci_dma_rx_complete()
Date: Thu, 13 Dec 2018 19:44:44 +0100 [thread overview]
Message-ID: <20181213184444.21904-5-geert+renesas@glider.be> (raw)
In-Reply-To: <20181213184444.21904-1-geert+renesas@glider.be>
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>
---
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
next prev parent reply other threads:[~2018-12-13 18:44 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-13 18:44 [PATCH v4 0/4] serial: sh-sci: Fix fallback to PIO on DMA failure Geert Uytterhoeven
2018-12-13 18:44 ` [PATCH v4 1/4] serial: sh-sci: Fix locking in sci_submit_rx() Geert Uytterhoeven
2018-12-17 13:17 ` Simon Horman
2018-12-13 18:44 ` [PATCH v4 2/4] serial: sh-sci: Fix crash in rx_timer_fn() on PIO fallback Geert Uytterhoeven
2018-12-17 13:22 ` Simon Horman
2018-12-17 13:27 ` Geert Uytterhoeven
2018-12-17 14:50 ` Simon Horman
2018-12-13 18:44 ` [PATCH v4 3/4] serial: sh-sci: Resume PIO in sci_rx_interrupt() on DMA failure Geert Uytterhoeven
2018-12-14 16:14 ` Wolfram Sang
2018-12-17 13:25 ` Simon Horman
2018-12-13 18:44 ` Geert Uytterhoeven [this message]
2018-12-17 13:29 ` [PATCH v4 4/4] serial: sh-sci: Fix fallback to PIO in sci_dma_rx_complete() Simon Horman
2018-12-16 2:22 ` [PATCH v4 0/4] serial: sh-sci: Fix fallback to PIO on DMA failure Rob Landley
2018-12-16 8:27 ` Geert Uytterhoeven
2018-12-17 14:05 ` Greg Kroah-Hartman
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