Re: [PATCH] tty: xilinx_uartps: Really fix id assignment

On 2020-07-13 14:10, Helmut Grohne wrote:

Hi Michal,

On Mon, Jul 13, 2020 at 01:49:38PM +0200, Michal Simek wrote:

quoted

On 13. 07. 20 9:11, Helmut Grohne wrote:

quoted

Let me try to enumerate those I know:

uart0    | uart1    | console | remark
---------+----------+---------+----------
serial0  | serial1  | ttyPS0  | regular case
serial0  | serial1  | ttyPS1  | normal assignment, second console
serial1  | serial0  | ttyPS0  | -> Jan Kiszka, broken since revert
disabled | serial0  | ttyPS0  | use only uart1 as serial0
serial0  | disabled | ttyPS0  | regular case with uart1 disabled

Out of these, I'm actively using configurations 3 and 4.

Which of these scenarios do you test already?

For above we are missing also others
serial1 | serial0 | ttyPS1
disabled| serial1 | ttyPS1

Is it actually possible to have ttyPS1, but no ttyPS0? I think I tried
doing that earlier and it resulted in there being ttyPS0, but no 
ttyPS1.

What if you also have a 16550 (in the PL) and give it the serial0 alias?
Or a UARTlite? The serialN alias is inappropriate to set the number for
ttyPSn. How are you supposed to create all of ttyPS0, ttyS0 and ttyUL0
using a single serial0 alias?

quoted

serial1 | disables | ttyPS0

I'm not sure what this is supposed to mean. When there is no serial0
alias, I'd expect ttyPS0 to be missing. However as indicated above that
is not what happens in practice. So either of these two configurations
seems invalid to me.

quoted

All of these above are just not setting any console= on bootargs.

We usually set the console= assignment on bootargs.

quoted

It means mix of these combinations is tested regularly but not all of
them. Do you see any other combination which is not supported?

I'm not aware of further relevant combinations.

Can we maybe trim down the matrix somehow? In my context, the need for
swapping the serial aliases arises from a limitation in u-boot-xlnx and
the desire to use one dtb for both linux and u-boot. It requires that
the serial0 alias is the console. Are there other reasons to swap them?
If not, maybe fixing u-boot would be an option?

Helmut

I think that it would be better if u-boot used a "console" alias.

Maarten


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