Hi Marek,
On 11/29/2013 05:50 PM, Marek Vasut wrote:
Hello Hector,
Terminate any DMA transfer and verify the TX FIFO is empty.
Signed-off-by: Hector Palacios <hector.palacios@xxxxxxxx>
---
drivers/tty/serial/mxs-auart.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/drivers/tty/serial/mxs-auart.c
b/drivers/tty/serial/mxs-auart.c index 9f0461778fc1..d9bf6e103f65 100644
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -782,6 +782,28 @@ static unsigned int mxs_auart_tx_empty(struct
uart_port *u) return 0;
}
+/*
+ * Flush the transmit buffer.
+ * Locking: called with port lock held and IRQs disabled.
+ */
+static void mxs_auart_flush_buffer(struct uart_port *u)
+{
+ struct mxs_auart_port *s = to_auart_port(u);
+ struct dma_chan *channel = s->tx_dma_chan;
+ unsigned int to;
+
+ if (auart_dma_enabled(s)) {
+ /* Avoid deadlock with the DMA engine callback */
+ spin_unlock(&s->port.lock);
+ dmaengine_terminate_all(channel);
+ spin_lock(&s->port.lock);
Can you not maybe just set some flag here to tell the DMA engine callback things
are shutting down and to don't do anything funny anymore ?
I copied these spin_lock protections from the amba-pl011.c driver.
The callbacks in the mxs-auart driver are not taking the lock but I was not sure if
any of the serial core functions they call are, so I thought it was a good idea to
take it.
+ }
+ /* Wait for the FIFO to flush */
+ to = u->timeout;
+ while (!mxs_auart_tx_empty(u) && to--)
+ mdelay(1);
Maybe you can put some cond_resched() into the loop to avoid wasting too many
cycles ?
Do you mean like this? Ok
while (!mxs_auart_tx_empty(u) && to--) {
cond_resched();
mdelay(1);
}
Best regards,
--
Hector Palacios
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