From: bigeasy@linutronix.de (Sebastian Andrzej Siewior)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 09/18] tty: serial: 8250_dma: handle error on TX submit
Date: Fri, 5 Sep 2014 21:02:44 +0200 [thread overview]
Message-ID: <1409943773-7874-10-git-send-email-bigeasy@linutronix.de> (raw)
In-Reply-To: <1409943773-7874-1-git-send-email-bigeasy@linutronix.de>
Right now it is possible that serial8250_tx_dma() fails and returns
-EBUSY. The caller (serial8250_start_tx()) will then enable
UART_IER_THRI which will generate an interrupt once the TX FIFO is
empty.
In serial8250_handle_irq() nothing will happen because up->dma is set
and so serial8250_tx_chars() won't be invoked. We end up with plenty of
interrupts and some "too much work for irq" output.
This patch introduces dma_tx_err in struct uart_8250_port to signal that
the last invocation of serial8250_tx_dma() failed so we can fill the TX
FIFO manually. Should the next invocation of serial8250_start_tx()
succeed then the dma_tx_err flag along with the THRI bit is removed and
DMA only usage may continue.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
drivers/tty/serial/8250/8250.h | 1 +
drivers/tty/serial/8250/8250_core.c | 4 +++-
drivers/tty/serial/8250/8250_dma.c | 30 +++++++++++++++++++++++++-----
3 files changed, 29 insertions(+), 6 deletions(-)
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index 1bcb4b2141a6..a63d198f8d03 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -41,6 +41,7 @@ struct uart_8250_dma {
size_t tx_size;
unsigned char tx_running:1;
+ unsigned char tx_err: 1;
};
struct old_serial_port {
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index e8df7cd85ba7..2101134e5031 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -1592,8 +1592,10 @@ int serial8250_handle_irq(struct uart_port *port, unsigned int iir)
status = serial8250_rx_chars(up, status);
}
serial8250_modem_status(up);
- if (!up->dma && (status & UART_LSR_THRE))
+ if ((!up->dma || (up->dma && up->dma->tx_err)) &&
+ (status & UART_LSR_THRE)) {
serial8250_tx_chars(up);
+ }
spin_unlock_irqrestore(&port->lock, flags);
return 1;
diff --git a/drivers/tty/serial/8250/8250_dma.c b/drivers/tty/serial/8250/8250_dma.c
index 148ffe4c232f..69e54abb6e71 100644
--- a/drivers/tty/serial/8250/8250_dma.c
+++ b/drivers/tty/serial/8250/8250_dma.c
@@ -36,8 +36,16 @@ static void __dma_tx_complete(void *param)
if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
uart_write_wakeup(&p->port);
- if (!uart_circ_empty(xmit) && !uart_tx_stopped(&p->port))
- serial8250_tx_dma(p);
+ if (!uart_circ_empty(xmit) && !uart_tx_stopped(&p->port)) {
+ int ret;
+
+ ret = serial8250_tx_dma(p);
+ if (ret) {
+ dma->tx_err = 1;
+ p->ier |= UART_IER_THRI;
+ serial_port_out(&p->port, UART_IER, p->ier);
+ }
+ }
spin_unlock_irqrestore(&p->port.lock, flags);
}
@@ -69,6 +77,7 @@ int serial8250_tx_dma(struct uart_8250_port *p)
struct uart_8250_dma *dma = p->dma;
struct circ_buf *xmit = &p->port.state->xmit;
struct dma_async_tx_descriptor *desc;
+ int ret;
if (uart_tx_stopped(&p->port) || dma->tx_running ||
uart_circ_empty(xmit))
@@ -80,8 +89,10 @@ int serial8250_tx_dma(struct uart_8250_port *p)
dma->tx_addr + xmit->tail,
dma->tx_size, DMA_MEM_TO_DEV,
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
- if (!desc)
- return -EBUSY;
+ if (!desc) {
+ ret = -EBUSY;
+ goto err;
+ }
dma->tx_running = 1;
@@ -94,8 +105,17 @@ int serial8250_tx_dma(struct uart_8250_port *p)
UART_XMIT_SIZE, DMA_TO_DEVICE);
dma_async_issue_pending(dma->txchan);
-
+ if (dma->tx_err) {
+ dma->tx_err = 0;
+ if (p->ier & UART_IER_THRI) {
+ p->ier &= ~UART_IER_THRI;
+ serial_out(p, UART_IER, p->ier);
+ }
+ }
return 0;
+err:
+ dma->tx_err = 1;
+ return ret;
}
EXPORT_SYMBOL_GPL(serial8250_tx_dma);
--
2.1.0
next prev parent reply other threads:[~2014-09-05 19:02 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-05 19:02 [PATCH v8 00/18] 8250-core based serial driver for OMAP + DMA Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 01/18] tty: serial: 8250_core: provide a function to export uart_8250_port Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 02/18] tty: serial: 8250_core: allow to overwrite & export serial8250_startup() Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 03/18] tty: serial: 8250_core: allow to set ->throttle / ->unthrottle callbacks Sebastian Andrzej Siewior
2014-09-08 23:33 ` Greg Kroah-Hartman
2014-09-09 0:41 ` Tony Lindgren
2014-09-05 19:02 ` [PATCH 04/18] tty: serial: 8250_core: add run time pm Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 05/18] tty: serial: 8250_core: read only RX if there is something in the FIFO Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 06/18] tty: serial: 8250_core: user the ->line argument as a hint in serial8250_find_match_or_unused() Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 07/18] tty: serial: 8250_core: remove UART_IER_RDI in serial8250_stop_rx() Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 08/18] tty: serial: Add 8250-core based omap driver Sebastian Andrzej Siewior
2014-09-08 16:39 ` Tony Lindgren
2014-09-05 19:02 ` Sebastian Andrzej Siewior [this message]
2014-09-05 19:02 ` [PATCH 10/18] tty: serial: 8250_dma: enqueue RX dma again on completion Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 11/18] tty: serial: 8250_dma: Add a TX trigger workaround for AM33xx Sebastian Andrzej Siewior
2014-09-08 16:41 ` Tony Lindgren
2014-09-08 16:45 ` Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 12/18] tty: serial: 8250_dma: optimize the xmit path due to UART_BUG_DMA_TX Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 13/18] tty: serial: 8250_dma: keep own book keeping about RX transfers Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 14/18] tty: serial: 8250_dma: handle the when UART response while DMA remains idle Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 15/18] tty: serial: 8250_dma: add pm runtime Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 16/18] arm: dts: am33xx: add DMA properties for UART Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 17/18] arm: dts: dra7: " Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 18/18] tty: serial: 8250: omap: add dma support Sebastian Andrzej Siewior
2014-09-08 14:46 ` [PATCH v8 00/18] 8250-core based serial driver for OMAP + DMA Frans Klaver
2014-09-08 15:15 ` Sebastian Andrzej Siewior
2014-09-08 16:33 ` Sebastian Andrzej Siewior
2014-09-08 18:25 ` Frans Klaver
2014-09-08 18:33 ` Frans Klaver
2014-09-09 19:41 ` Sebastian Andrzej Siewior
2014-09-10 14:15 ` Frans Klaver
2014-09-10 16:56 ` Sebastian Andrzej Siewior
2014-09-08 17:40 ` Tony Lindgren
2014-09-08 17:55 ` Tony Lindgren
2014-09-09 7:33 ` Sebastian Andrzej Siewior
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