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Date: 30 Sep 2004 10:42:24 +0200
Date: Thu, 30 Sep 2004 10:42:24 +0200
From: Andi Kleen <ak@muc.de>
To: Vojtech Pavlik <vojtech@suse.cz>
Cc: akpm@osdl.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Readd panic blinking in 2.6
Message-ID: <20040930084224.GA28779@muc.de>
References: <m3llet4456.fsf@averell.firstfloor.org> <20040929132134.GA3770@ucw.cz>
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> 
> Something like
> 
> 	spin_lock_irqsave(&i8042_lock, flags);
> 	i8042_flush();
> 	i8042_ctr &= ~I8042_CTR_KBDINT & ~I8042_CTR_AUXINT;
> 	i8042_command(&i8042_ctr, I8042_CMD_CTL_WCTR);
> 	i8042_wait_write();
> 	i8042_write_data(0xed);
> 	i8042_wait_read();
> 	i8042_flush();
> 	i8042_wait_write();
> 	i8042_write_data(led);
> 	i8042_wait_read();
> 	i8042_flush();
> 	spin_unlock_irqrestore(&i8042_lock, flags);
> 
> would be safer and more correct.

That all takes far too many locks. The risk of deadlocking during
panic is too great. I think the delay is fine (worked great under 2.4),
just need to fix the IBF issue you mentioned.

-Andi