Re: [PATCH v5] serial: support for 16550A serial ports on LP-8x4x

Sergei Ianovich
2015-12-19T08:11:31Z

On Wed, 2015-12-16 at 11:26 +0100, Arnd Bergmann wrote:
> On Wednesday 16 December 2015 11:04:57 Sergei Ianovich wrote:
> > On Tue, 2015-12-15 at 22:51 +0100, Arnd Bergmann wrote:
> > > 'x' wildcards in the name of the board seem important. There are
> > devices
> > made by the same vendor without 8 or 4 in their name. Those devices
> > either are not shipped with linux or are base on a x86 platform.
> >
> > Does this justify the choice of the compatible string?
>
> What I meant was that you should use the specific numbers of one
> machine,
> precisely for the reason you list above.
>
> If there is e.g. a LP-8040 and a LP-8141 today, and you use lp8x4x in
> the compatible string to cover both, this will no longer work when the
> vendor comes out with a LP8047 that is completely different.
>
> Instead, what you should do is to use the compatible string to
> identify
> one particular board (e.g. the first one that used this setup), and
> then list the other ones as compatible with this. You can also add the
> other board names in addition, e.g.
>
> compatible = "icpdas,uart-lp8041", "icpdas,uart-lp8040";
>
> for a lp8041 that is compatible with the lp8040. If it turns out later
> that they are not entirely compatible, we can work around this in the
> driver by checking for the lp8041 string that will be matched first,
> while
> the lp8040 can be used by the driver to match the entire family of
> compatible machines (no need to list every one in the driver).

I'll try to be more specific. This driver will support ports on LP-8081,
LP-8141, LP-8441, LP-8841. Last time I checked the vendor was announcing
a series with 3 as the last digit. They use lp8x4x name, eg. in
documentation like `LP-8x4x_ChangeLog.txt`. They ship their proprietary
SDK in `lp8x4x_sdk_for_linux.tar`. All of this implies that it is a
single board.