* SAM9-L9260: TXD1 is not working on AT91SAM9260
@ 2010-07-10 7:09 Stefan Schoenleitner
0 siblings, 0 replies; 4+ messages in thread
From: Stefan Schoenleitner @ 2010-07-10 7:09 UTC (permalink / raw
To: linux-embedded
Hi,
I have an Olimex SAM9-L9260 board with an AT91SAM9260 controller on it.
The board is running a sound-2.6 git kernel (2.6.35).
My problem is that for USART1 (which uses the RXD1 and TXD1 pins), the
transmit pin (i.e. TXD1) is not working.
I looked at it with my scope and discovered that it is high all the time
(which is most likely due to the configured pull-up resistor).
Here is what I did to get the UART up and running (just like what I
already did for the DBG UART and UART0):
In my board file (arch/arm/mach-at91/board-sam9-l9260.c) I added the
following line to ek_map_io(), to register USART1 as ttyS2:
-----------------------------------------------------------------------
at91_register_uart(AT91SAM9260_ID_US1, 2, 0);
-----------------------------------------------------------------------
A look at at91sam9260_devices.c reveals that this will lead to a call of
-----------------------------------------------------------------------
configure_usart1_pins(pins);
-----------------------------------------------------------------------
which in turn does the following:
-----------------------------------------------------------------------
at91_set_A_periph(AT91_PIN_PB6, 1); /* TXD1 */
at91_set_A_periph(AT91_PIN_PB7, 0); /* RXD1 */
-----------------------------------------------------------------------
Hence the pins PB6 and PB7 are configured to be UART pins.
I also made sure that there is no other code, that sets the
functionality of those pins to something else (e.g. pin PB6 could also
be used as TCLK1).
Then, when I boot the kernel, I get the following lines, which show that
the UARTs are recognized:
-----------------------------------------------------------------------
atmel_usart.0: ttyS0 at MMIO 0xfefff200 (irq = 1) is a ATMEL_SERIAL
atmel_usart.1: ttyS1 at MMIO 0xfffb0000 (irq = 6) is a ATMEL_SERIAL
atmel_usart.2: ttyS2 at MMIO 0xfffb4000 (irq = 7) is a ATMEL_SERIAL
-----------------------------------------------------------------------
While this looks good so far, the odd behavior is that I can correctly
receive data on /dev/ttyS2 (i.e. data is received on the RXD1/PB7 pin),
but I can not send (i.e. *no* data is being transmitted on the TXD1/PB6
pin).
* Is this a bug in the kernel or am I doing something wrong here ?
* Did you experience similar behavior on the at91sam9260 ?
As I already said, I have done this with other UART devices as well
(i.e. USART0) and it worked flawlessly.
cheers,
stefan
^ permalink raw reply [flat|nested] 4+ messages in thread
* SAM9-L9260: TXD1 is not working on AT91SAM9260
@ 2010-07-10 7:10 Stefan Schoenleitner
2010-07-11 17:05 ` Sergey Matyukevich
0 siblings, 1 reply; 4+ messages in thread
From: Stefan Schoenleitner @ 2010-07-10 7:10 UTC (permalink / raw
To: linux-arm-kernel
Hi,
I have an Olimex SAM9-L9260 board with an AT91SAM9260 controller on it.
The board is running a sound-2.6 git kernel (2.6.35).
My problem is that for USART1 (which uses the RXD1 and TXD1 pins), the
transmit pin (i.e. TXD1) is not working.
I looked at it with my scope and discovered that it is high all the time
(which is most likely due to the configured pull-up resistor).
Here is what I did to get the UART up and running (just like what I
already did for the DBG UART and UART0):
In my board file (arch/arm/mach-at91/board-sam9-l9260.c) I added the
following line to ek_map_io(), to register USART1 as ttyS2:
-----------------------------------------------------------------------
at91_register_uart(AT91SAM9260_ID_US1, 2, 0);
-----------------------------------------------------------------------
A look at at91sam9260_devices.c reveals that this will lead to a call of
-----------------------------------------------------------------------
configure_usart1_pins(pins);
-----------------------------------------------------------------------
which in turn does the following:
-----------------------------------------------------------------------
at91_set_A_periph(AT91_PIN_PB6, 1); /* TXD1 */
at91_set_A_periph(AT91_PIN_PB7, 0); /* RXD1 */
-----------------------------------------------------------------------
Hence the pins PB6 and PB7 are configured to be UART pins.
I also made sure that there is no other code, that sets the
functionality of those pins to something else (e.g. pin PB6 could also
be used as TCLK1).
Then, when I boot the kernel, I get the following lines, which show that
the UARTs are recognized:
-----------------------------------------------------------------------
atmel_usart.0: ttyS0 at MMIO 0xfefff200 (irq = 1) is a ATMEL_SERIAL
atmel_usart.1: ttyS1 at MMIO 0xfffb0000 (irq = 6) is a ATMEL_SERIAL
atmel_usart.2: ttyS2 at MMIO 0xfffb4000 (irq = 7) is a ATMEL_SERIAL
-----------------------------------------------------------------------
While this looks good so far, the odd behavior is that I can correctly
receive data on /dev/ttyS2 (i.e. data is received on the RXD1/PB7 pin),
but I can not send (i.e. *no* data is being transmitted on the TXD1/PB6
pin).
* Is this a bug in the kernel or am I doing something wrong here ?
* Did you experience similar behavior on the at91sam9260 ?
As I already said, I have done this with other UART devices as well
(i.e. USART0) and it worked flawlessly.
cheers,
stefan
^ permalink raw reply [flat|nested] 4+ messages in thread
* SAM9-L9260: TXD1 is not working on AT91SAM9260
2010-07-10 7:10 SAM9-L9260: TXD1 is not working on AT91SAM9260 Stefan Schoenleitner
@ 2010-07-11 17:05 ` Sergey Matyukevich
2010-07-12 6:00 ` Stefan Schoenleitner
0 siblings, 1 reply; 4+ messages in thread
From: Sergey Matyukevich @ 2010-07-11 17:05 UTC (permalink / raw
To: linux-arm-kernel
Hello Stefan,
> In my board file (arch/arm/mach-at91/board-sam9-l9260.c) I added the
> following line to ek_map_io(), to register USART1 as ttyS2:
>
> -----------------------------------------------------------------------
> at91_register_uart(AT91SAM9260_ID_US1, 2, 0);
> -----------------------------------------------------------------------
You modify here default configuration which is
at91_register_uart(AT91SAM9260_ID_US1, 2,
ATMEL_UART_CTS | ATMEL_UART_RTS);
Do you turn off hardware handshake when you configure
your test setup for ttyS2 ?
Thanks,
Sergey
^ permalink raw reply [flat|nested] 4+ messages in thread
* SAM9-L9260: TXD1 is not working on AT91SAM9260
2010-07-11 17:05 ` Sergey Matyukevich
@ 2010-07-12 6:00 ` Stefan Schoenleitner
0 siblings, 0 replies; 4+ messages in thread
From: Stefan Schoenleitner @ 2010-07-12 6:00 UTC (permalink / raw
To: linux-arm-kernel
Hi Sergey,
Sergey Matyukevich wrote:
> Do you turn off hardware handshake when you configure
> your test setup for ttyS2 ?
exactly this was the problem.
I reused my code that I wrote earlier for uart communication with
RTC/CTS, but then missed to turn hw handshaking off.
Hence all transmissions were being blocked.
Thank you for your hint, without it I might still be looking for the
problem in the wrong places.
cheers,
stefan
^ permalink raw reply [flat|nested] 4+ messages in thread
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2010-07-10 7:10 SAM9-L9260: TXD1 is not working on AT91SAM9260 Stefan Schoenleitner
2010-07-11 17:05 ` Sergey Matyukevich
2010-07-12 6:00 ` Stefan Schoenleitner
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2010-07-10 7:09 Stefan Schoenleitner
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