linux-kernel - Re: [PATCH 01/12] thinkpad_ec: New driver for ThinkPad embedded controller access

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Message-ID: <20060807231557.GA2759@elf.ucw.cz>
Date:	Tue, 8 Aug 2006 01:15:57 +0200
From:	Pavel Machek <pavel@...e.cz>
To:	Shem Multinymous <multinymous@...il.com>
Cc:	Robert Love <rlove@...ve.org>, Jean Delvare <khali@...ux-fr.org>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	linux-kernel@...r.kernel.org, hdaps-devel@...ts.sourceforge.net
Subject: Re: [PATCH 01/12] thinkpad_ec: New driver for ThinkPad embedded controller access

Hi!

> Thanks for the sign-offs!

No problem.

> >> +module_param_named(debug, tp_debug, int, 0600);
> >> +MODULE_PARM_DESC(debug, "Debug level (0=off, 1=on)");
> >> +
> >> +/* A few macros for printk()ing: */
> >> +#define DPRINTK(fmt, args...) \
> >> +  do { if (tp_debug) printk(KERN_DEBUG fmt, ## args); } while (0)
> >
> >Is not there generic function doing this?
> 
> None that I found. Many drivers do it this way.

linux/kernel.h : pr_debug() looks similar.

> >> +EXPORT_SYMBOL_GPL(thinkpad_ec_lock);
> >> +EXPORT_SYMBOL_GPL(thinkpad_ec_try_lock);
> >> +void thinkpad_ec_unlock(void)
> >> +{
> >> +     up(&thinkpad_ec_mutex);
> >> +}
> >> +
> >
> >Do we need these wrappers? Perhaps just directly exporting the mutex?
> 
> Yes, we may end up needing to lock away other systems (ACPI?) that
> touch the same ports. Apparently not an issue right now, but could
> change with new firmware.
> Also, that's what Alan Cox told me to do. :-)

Okay... but do we really need try_lock variant? lock/unlock would be
okay, but what is try_lock semantics when taking multiple locks...?

> >> +     struct dmi_device *dev = NULL;
> >
> >unneeded initializer.
> 
> On a local variable?!

You were right, but see the other mail.

> >> +static int __init thinkpad_ec_init(void)
> >> +{
> >> +     if (!check_dmi_for_ec()) {
> >> +             printk(KERN_ERR "thinkpad_ec: no ThinkPad embedded 
> >controller!\n");
> >> +             return -ENODEV;
> >
> >KERN_ERR is little strong here, no?
> 
> Not sure what's the right one. The user tried to load a module and the
> module can't do that; I saw some drivers use KERN_ERR some
> KERN_WARNING in similar cases. Is there some guideline on choosing
> printk levels?

Well, this will also trigger for thinkpad module compiled into kernel,
right?
								Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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