Problem when using ttyS1 for debug


(김호연지기) #1

Hi all, I have a short question about BPI-M1.

What I’m trying to do is to change the default console of Linux kernel from UART0 (ttyS0) to another. FYI, I’m now using mainline Linux (v4.9), mainline u-boot (v2017.01) and appending ‘sun7i-a20-bananapi.dtb’ to zImage. And this is my current status …

UART connection : (UART0 for u-boot log printing, and UART3 for Linux log printing)

bootargs on DTS :


With these kind of configuration, I can see Linux booting log printed on ttyS1 (through UART3), but the problem is that the input is totally not working… (I cannot move on from ‘Please press Enter to activate this console.’) and I have no idea why the input is not working on ttyS1 (Of course, I double-checked my UART connection, and everything worked really well on ttyS0 (UART0).)

Is there anyone who can help me out with this issue? Thanks


(Igor) #2

Those pins are multiplexed and UART1 pins might be in use by something else by default, perhaps I2C?

And you are asking question in wrong place: linux-sunxi.org


(김호연지기) #3

Thanks for your reply.

First of all, what I’m trying to use for Linux console is UART3 pins (which is aliased as serial1 in dtb file) not UART1 and as I mentioned on original post, the console output is working well, so UART3 seems fine to use for console as far as I know.

Secondly, are you suggesting me to use linux-sunxi community rather than banana pi forum? Because, what I thought is that this might be the problem about GPIO or something about banana-pi board, so I thought it is proper to ask on this forum …

Again, thanks for your reply.