Am 2022-11-22 09:25, schrieb Jiri Slaby:
On 22. 11. 22, 9:23, Jiri Slaby wrote:
On 22. 11. 22, 9:18, Michael Walle wrote:
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?
Yes, that was exactly the next step to try. The datasheet doesn't tell
much what happens when TXDIS is written while the characters are
transmitted.
Side note: your usart doesn't use dma. It's PIO (hence all that
uart_tx_helper()). And the attached patch doesn't touch TXDIS for
non-DMA case. I.e. it should transmit the final character (and nothing
more).
ok ;)
expect from "s/id_dma/is_dma/", this patch works. thanks!
-michael
