linux-kernel - Re: [PATCH 1/1] LinuxPPS: Pulse per Second support for Linux

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Message-ID: <20070216205747.GC4641@enneenne.com>
Date:	Fri, 16 Feb 2007 21:57:47 +0100
From:	Rodolfo Giometti <giometti@...eenne.com>
To:	Jan Dittmer <jdi@....org>
Cc:	linux-kernel@...r.kernel.org, linuxpps@...enneenne.com
Subject: Re: [PATCH 1/1] LinuxPPS: Pulse per Second support for Linux

On Fri, Feb 16, 2007 at 08:56:18PM +0100, Jan Dittmer wrote:

> Drop the linux prefix. It's in the linux kernel after all.

Ok.

> > +PROCFS support
> > +--------------
> 
> New features shouldn't introduce new /proc stuff.

It's a must? I can leave procfs for backward compatibility with old
utilities?

> Add to MAINTAINERS

Ok.

> Your way to hook into lp and 8250 is pretty gross. It should at least be
> possible to deactivate it via the kernel command line, but it would be
> a lot nicer to have pps_lp and pps_8250 modules which you can load. Also

I think it's not possible... however the Russell's suggestions should
go in that direction.

> what happens if you've multiple lp ports? How do you control which to
> grab?

No way... I can add a specific flag as for uart lines or a kernel
module parameter.

> - don't implement your own dbg() stuff, use dprintk and friends
> - drop the inlines, gcc will do the right thing.

Ok. Ok.

> Perhaps just implement empty defines for the none pps cases and get
> rid of the ifdefs? But this should really be controllabe via
> sysfs or such.

Mmm... let me think about howto implement that...

> help text

Ok.

> help text and difference to CLIENT_LP?

Ok.

> Why no dynamically allocated array?

It's easier! :P

Also it's very difficult having more that 3 or 4 PPS sources in a
system.

> I wouldn't bet on that.

Why not? =:-o

Also locking instructions may add extra code and delay the timestamp
recording...

> Doesn't match filename

I'm going to fix it.

> > +++ b/drivers/pps/procfs.c
> 
> I'd drop that completely.

:'(

> You read the comment above your line?

No, sorry. I'm going to choose another id number... or can I keep 17?

> These should use dprintk and friends

Ok.

> Isn't something like 4 more reasonable (lp + 8250 + ktimer?)

It should be enought...

> I think you can drop the volatiles, there was a discussion some time ago
> that they mostly waste of words.

I see...

> This one looks pretty fishy. After the check you normally want
> to use it, don't you? And then you already lost the guarantee.

You are right...

> > +#define to_class_dev(obj) container_of((obj), struct class_device, kobj)
> 
> pretty generic name.

I should change it?

> Have you thought about 32/64bit issues?

No. I have no 64 bits machine to test the code...

> Function in .h?

I'm going to check it.

Thanks for your suggestions,

Rodolfo

-- 

GNU/Linux Solutions                  e-mail:    giometti@...eenne.com
Linux Device Driver                             giometti@...dd.com
Embedded Systems                     		giometti@...ux.it
UNIX programming                     phone:     +39 349 2432127
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