| Message ID | 20181213184444.21904-5-geert+renesas@glider.be (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | serial: sh-sci: Fix fallback to PIO on DMA failure | expand |
On Thu, Dec 13, 2018 at 07:44:44PM +0100, Geert Uytterhoeven wrote: > 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; Invalidating cookie_rx already appears twice, in two different forms. Perhaps a helper is appropriate. > + 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); Likewise, logic ti redirect interrupts seems to already be present in rx_timer_fn(). > spin_unlock_irqrestore(&port->lock, flags); > } > > -- > 2.17.1 >
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); }
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(-)