linux-kernel - Re: [Bugme-new] [Bug 8378] New: Averatec 3156X laptop doesn't reboot with kernels

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Message-Id: <18bbbf39d8da8a578ab7eab477f500c1@kernel.crashing.org>
Date:	Sat, 28 Apr 2007 13:23:17 +0200
From:	Segher Boessenkool <segher@...nel.crashing.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	"bugme-daemon@...nel-bugs.osdl.org" 
	<bugme-daemon@...zilla.kernel.org>,
	Truxton Fulton <trux@...xton.com>,
	linux-kernel@...r.kernel.org, lee-in-berlin@....de
Subject: Re: [Bugme-new] [Bug 8378] New: Averatec 3156X laptop doesn't reboot with kernels > 2.6.13.5 (responsible commit found)

That patch says

> +               outb(0x60, 0x64);       /* write Controller Command 
> Byte */
> +               udelay(50);
> +               kb_wait();
> +               udelay(50);
> +               outb(0x14, 0x60);       /* set "System flag" */

so the comment doesn't agree with the code: it sets
all flags in the command byte, not just the system
flag.  Perhaps importantly, it disables the keyboard
clock.  Why not do a read-modify-write sequence instead?
Something like

                outb(0x20, 0x64);       /* read Controller Command Byte 
*/
                udelay(50);
                kb_wait();
                udelay(50);
                u8 cmd = inb(0x60);
                udelay(50);
                kb_wait();
                udelay(50);
                outb(0x60, 0x64);       /* write Controller Command Byte 
*/
                udelay(50);
                kb_wait();
                udelay(50);
                outb(cmd | 0x04, 0x60); /* set "System flag" */

Segher

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