Hello Uwe,
On 10/01/2013 09:48 PM, Uwe Kleine-König wrote:
Hello Hector,
On Tue, Oct 01, 2013 at 06:18:35PM +0200, Hector Palacios wrote:
The shutdown function was not waiting for the DMA buffer to flush
before disabling the AUART. This lead to many bytes not being
transferred (specially at low baudrates), as they were still in the
DMA buffer when the AUART was shutdown.
This patch also adds the check for the BUSY flag.
Signed-off-by: Hector Palacios <hector.palacios@xxxxxxxx>
https://jira.digi.com/browse/DEL-616
What is this? This isn't available in public DNS.
Sorry, copy&paste error. I'll remove it.
---
drivers/tty/serial/mxs-auart.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
index f85b8e6..0d8b2ca 100644
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -750,12 +750,26 @@ static int mxs_auart_startup(struct uart_port *u)
return 0;
}
+static unsigned int mxs_auart_tx_empty(struct uart_port *u);
+
static void mxs_auart_shutdown(struct uart_port *u)
{
struct mxs_auart_port *s = to_auart_port(u);
+ unsigned int to;
+
+ if (auart_dma_enabled(s)) {
+ /* Wait enough time to flush DMA buffer completely */
+ to = u->timeout * UART_XMIT_SIZE / u->fifosize;
u->timeout is the time needed to send one char, right? UART_XMIT_SIZE is
the size of the circular buffer, fifosize is the size of the fifo. I
don't get what you get by dividing by the fifosize. I would have
expected something like:
u->timeout * min(UART_XMIT_SIZE, u->fifosize)
Can you explain, maybe in a comment along the code for the next person
not understanding?
u->timeout is *not* the time needed to send one char but the time needed to flush the
complete port fifo (see uart_update_timeout() in serial_core.c where it is set).
UART_XMIT_SIZE is the number of bytes in the DMA buffer, so I divide the max number of
bytes in the FIFO by the FIFO size and multiply by the FIFO timeout.
I wonder if the individual driver is the right place this must be fixed
in or if there should be (or even exists) some help form the serial
framework?!
Good question, the issue should exit in other DMA drivers as well.
Best regards,
--
Hector Palacios
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