Am 2022-11-22 09:09, schrieb Michael Walle:
Hi,
Am 2022-11-22 08:02, schrieb Jiri Slaby:
On 21. 11. 22, 21:27, Michael Walle wrote:
This will break serial output for the userspace on my board
(arch/arm/boot/dts/lan966x-kontron-kswitch-d10-mmt*dts). The
uart_port_tx()
helper will call __port->ops->stop_tx(__port) if
uart_circ_chars_pending()
returns 0. But the code above, doesn't do that. In fact, removing the
stop_tx() call in the helper macro, will fix the console output.
Any ideas how to fix that?
Hm, so ATMEL_US_TXRDY is removed from tx_done_mask in stop_tx, but not
added back in start_tx. So the tx interrupt is never handled (the tx
tasklet is not scheduled to send the queue chars) in
atmel_handle_transmit().
Any chance, the below fixes it?
diff --git a/drivers/tty/serial/atmel_serial.c
b/drivers/tty/serial/atmel_serial.c
index 11bf2466390e..395370e0c77b 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -596,6 +596,8 @@ static void atmel_start_tx(struct uart_port *port)
/* re-enable PDC transmit */
atmel_uart_writel(port, ATMEL_PDC_PTCR,
ATMEL_PDC_TXTEN);
+ atmel_port->tx_done_mask |= ATMEL_US_TXRDY;
+
/* Enable interrupts */
atmel_uart_writel(port, ATMEL_US_IER,
atmel_port->tx_done_mask);
thanks,
Unfortunately, that doesn't help. Btw, some characters are transmitted:
[ 6.219356] Key type dns_resolver registered
[ 6.223679] Registering SWP/SWPB emulation handler
[ 6.247530] Loading compiled-in X.509 certificates
[ 6.288467] Freeing unused kernel image (initmem) memory: 1024K
[ 6.297789] Run /init as init process
WbSOROSOSOSOSOStarting linuxptp system clock synchronization: O
-michael
But you made me look at atmel_stop_tx() and there is this:
/*
* Disable the transmitter.
* This is mandatory when DMA is used, otherwise the DMA buffer
* is fully transmitted.
*/
atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXDIS);
Removing that write, will also fix the problem. Could it be, that
the transmit is still active (via DMA) but the driver will call
tx_stop() and then stop the transmission in the background?
-michael
