[PATCH v4 2/2] dma: Add Xilinx AXI Central Direct Memory Access Engine driver support

Paul Bolle pebolle at tiscali.nl
Tue Jun 9 04:59:35 PDT 2015

On Tue, 2015-06-09 at 12:41 +0200, Michal Simek wrote:
> On 06/09/2015 10:15 AM, Paul Bolle wrote:
> > Mistakes I've seen made since I started checking this stuff (a few
> > months ago):
> > - typos in the license ident, say "GPLv2", "GPL V2", or "BSD": generates
> > a warning when module is loaded and taints kernel. People still get this
> > wrong. A test in checkpatch for these typos was submitted a while ago,
> > but it never got added;
> Any reason for that? just lost or any problem ?

Submitter lost interest, I guess. Check
https://lkml.org/lkml/2015/5/22/279 and note that there was no response.

> > - not adding MODULE_LICENSE() to a module: also generates a warning when
> > module is loaded and taints kernel. People still get this wrong;
> > - adding MODULE_LICENSE() to built-in only code: pointless at best, and
> > annoying for reviewers ("Hey, did the submitter intend to write built-in
> > only code or modular code?");
> > - using "Dual BSD/GPL" but not a trace of the BSD license blurb in
> > sight, while adding that blurb is one of the very few requirements this
> > license actually has;
> > - license mismatch, say comment blurb states "GPL v2 (or later)" but
> > MODULE_LICENSE() ident states "GPL v2" only (or vice versa): very easy
> > mistake to make, happens once or twice a week.  
> What do you mean by vice versa?
> GPL v2 header and MODULE_LICENSE("GPL") should be fine right?

Not really. The license in the comment at the top of the file is just
GPL v2, while the MODULE_LICENSE ident adds "or later" and thus the
right to "uplicense". So which is it: just "GPL v2" or "GPL v2 (or
later)"? Can't say in that case.

> > Did I miss anything in that list?
> I think you miss MODULE_ALIAS problems.
> https://lkml.org/lkml/2014/3/17/301

That's outside of the license stuff, but thanks for thye pointer anyway.

> > I'm afraid that most of the above can only be caught reliably by
> > attention to detail by submitters and reviewers. That's a pity, because
> > checking for that stuff is about as boring as it gets. (What does that
> > say about me?)
> yep. I have never looked at the details about these license module
> stuff. But definitely great to have this list - will record it and keep
> my eye on our xilinx drivers.
> BTW: Some time ago we discussed SPDX License Identifier which could
> simplify license checking.
> https://lkml.org/lkml/2014/2/21/21

I think I saw that fly by. Wasn't that idea shot down?


Paul Bolle

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