Re: [PATCH 0/3] Deterministic UART numbering on Samsung SoCs

[Russell King - ARM Linux]

On Thu, Jun 26, 2014 at 01:24:32PM +0200, Tomasz Figa wrote:
> Current Samsung UART driver relies on probe order of particular
> samsung-uart instances, which makes it impossible to get proper
> initialization of ports when not all ports are available on board,
> not even saying of deterministic device naming.
> 
> This series intends to fix this situation by adding support to parse
> aliases from device tree and use them to assign instance IDs to
> particular port instances.

How about instead exporting the path/id information so that userspace
can create /dev/serial/by-{path,id}/... for internal devices instead?

The problem you're raising is very much the same problem you have when
there are multiple USB serial devices connected to the machine - you
just get a bunch of /dev/ttyUSB* devices which are unordered (they can
change on each boot, or change order if you disconnect and reconnect
them.)

/dev/serial/by-{path,id}/ allows for a much more stable path.

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