[Pkg-raspi-maintainers] Serial on Raspi 3

[Michael Stapelberg]

I agree that the Raspberry Pi 3 serial situation is a mess :(.

You can find a device tree modification to swap the serial ports here:
https://github.com/gokrazy/kernel/blob/master/0001-
expose-UART0-ttyAMA0-on-GPIO-14-15-disable-UART1-tty.patch

I don’t have any experience with the device tree overlay mechanism which
the firmware uses, so I can’t give any more guidance, but perhaps you can
make it work?

If this doesn’t help, I’d suggest contacting https://github.com/pelwell,
who helped me in https://github.com/raspberrypi/firmware/issues/752.

On Mon, Feb 19, 2018 at 11:16 AM, Thomas Wuensche <wuensche at ems-wuensche.com
> wrote:

> Hello, thank you for your reply. To me it does not seem
> like an upstream problem, but as a raspi specific mess
> with the serial port hardware setup, concretely the question,
> which of the two uarts is mapped to the port pins.
>
> In my case the miniuart seems to be mapped to the port
> pins (and can't be changed to 115200 8n1, which is what
> I would like to use). If I output to ttyS1 (which I assume
> to be the miniuart) I can see signals on the port pins.
>
> The full uart (pl011) seems not to be mapped to the pins.
> I can change parameters with stty, but do not see any
> signals on the pins when writing to that port (ttyAMA0).
>
> As a side note I have the impression that changes to
> config.txt are without effect (for example "enable_uart").
> I understand that should be read and processed by the
> binary module to set up hardware, right? Whom can I contact
> regarding behaviour of the binary module?
>
> Raspbian seems to deal with such things with device tree
> overlays to configure the hardware on boot, but I can't
> see an equivalent on debian.
>
> Any more hints? Thank you!
>
> Best regards,
>
> Thomas Wuensche
>
> Am 18.02.2018 um 22:08 schrieb Michael Stapelberg:
> > [+cc pkg-raspi-maintainers, in case someone else has run into this issue
> > before]
> >
> > I have only verified the serial port works with 115200 8n1.
> >
> > Please report an upstream Linux kernel bug, as there are no
> > Debian-specific changes in this area of the kernel.
> >
> > Sorry I can’t be of more help,
> >
> > On Sun, Feb 18, 2018 at 11:59 AM, Thomas Wuensche
> > <wuensche at ems-wuensche.com <mailto:wuensche at ems-wuensche.com>> wrote:
> >
> >     Hello,
> >
> >     after having troubles with the unclear kernel upgrade structures
> >     on raspbian I switched to your debian image. However I have troubles
> >     with the serial port - hope you can help.
> >
> >     My project needs serial data from a sensor module. If I go with
> >     serial-over-usb it works, however not with direct connection.
> >
> >     After a number of fruitless tries I have the following constellation:
> >
> >     If I output serial data to /dev/ttyS1 I can see the data on the port
> >     lines with the oscilloscope and read back the data from that port.
> >     However when trying to switch line parameters, stty does not come
> >     back. So I can not adjust the required terminal parameters.
> >
> >     If I try the same with /dev/ttyAMA0 I do not see anything on the
> >     port and can't read back data. However changing port parameters
> >     works. In message log I have a line:
> >
> >     uart-pl011 3f201000.serial: no DMA platform data
> >
> >     I have tried both with and without "enable_uart=1" in
> >     /boot/firmware/config.txt
> >
> >     As I'm playing for weeks now with that issue and no result I would
> >     be glad if you could help me!
> >
> >     Best regards,
> >
> >     Thomas Wuensche
> >     --
> >     EMS Dr. Thomas Wuensche e.K.
> >     Sonnenhang 3
> >     85304 Ilmmuenster
> >     HR Ingolstadt, HRA 170106
> >
> >     Phone: +49-8441-490260 <tel:%2B49-8441-490260>
> >     Fax  : +49-8441-81860 <tel:%2B49-8441-81860>
> >     http://www.ems-wuensche.com
> >
> >
> >
> >
> > --
> > Best regards,
> > Michael
> --
> EMS Dr. Thomas Wuensche e.K.
> Sonnenhang 3
> 85304 Ilmmuenster
> HR Ingolstadt, HRA 170106
>
> Phone: +49-8441-490260
> Fax  : +49-8441-81860
> http://www.ems-wuensche.com
>



-- 
Best regards,
Michael
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