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From: Andrew Morton <akpm@linux-foundation.org>
To: Mark Pearson <devnull.port@googlemail.com>
Cc: Karol Kozimor <sziwan@hell.org.pl>, Julia Lawall <julia@diku.dk>,
	corentincj@iksaif.net, sziwan@users.sourceforge.net,
	acpi4asus-user@lists.sourceforge.net,
	linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org,
	Len Brown <lenb@kernel.org>
Subject: Re: [PATCH 2/9] drivers/acpi/asus_acpi.c: Correct use of ! and &
Date: Thu, 28 Feb 2008 21:55:03 -0800	[thread overview]
Message-ID: <20080228215503.b942bb3c.akpm@linux-foundation.org> (raw)
In-Reply-To: <47C5ABFB.3050607@googlemail.com>

On Wed, 27 Feb 2008 19:29:15 +0100 Mark Pearson <devnull.port@googlemail.com> wrote:

> Karol Kozimor wrote:
> > On 26-02-2008, at 21:42, Julia Lawall wrote:
> >>      if (invert)        /* invert target value */
> >> -        led_out = !led_out & 0x1;
> >> +        led_out = !(led_out & 0x1);
> >>
> >>      if (!write_acpi_int(hotk->handle, ledname, led_out, NULL))
> >>          printk(KERN_WARNING "Asus ACPI: LED (%s) write failed\n",
> > 
> > 
> > IIRC we're just supposed to flip the last bit here, so the original code
> > is correct.
> > Best regards,
> > 
> 
> Seems an odd way of doing:
> 
> 	led_out ^= 0x01;

It does.

> It this due to some optimisation?

Surely not ;)

That code has been there for many years.

I changed the patch to this:

--- a/drivers/acpi/asus_acpi.c~drivers-acpi-asus_acpic-correct-use-of-and
+++ a/drivers/acpi/asus_acpi.c
@@ -610,7 +610,7 @@ write_led(const char __user * buffer, un
 	    (led_out) ? (hotk->status | ledmask) : (hotk->status & ~ledmask);
 
 	if (invert)		/* invert target value */
-		led_out = !led_out & 0x1;
+		led_out = !led_out;
 
 	if (!write_acpi_int(hotk->handle, ledname, led_out, NULL))
 		printk(KERN_WARNING "Asus ACPI: LED (%s) write failed\n",
_


  reply	other threads:[~2008-02-29  5:56 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-26 20:42 Julia Lawall
2008-02-27 17:03 ` Karol Kozimor
2008-02-27 17:41   ` Julia Lawall
2008-02-27 18:29   ` Mark Pearson
2008-02-29  5:55     ` Andrew Morton [this message]
2008-02-29  6:10       ` Matthew Wilcox
2008-02-29  6:14         ` Matthew Wilcox
2008-02-29  6:19         ` Andrew Morton
2008-02-29 11:01       ` Julia Lawall
2008-02-29 11:08         ` Andrew Morton
2008-02-29 18:06       ` Mark Pearson
2008-02-29 21:33         ` Andrew Morton

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