linux-kernel - serial 8250, sysrq, and break

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Message-Id: <5414CB1F-F665-4B8B-8C46-8805F1CC7774@kernel.crashing.org>
Date:	Mon, 19 Feb 2007 16:42:41 -0600
From:	Kumar Gala <galak@...nel.crashing.org>
To:	rmk+serial@....linux.org.uk
Cc:	Linux Kernel list <linux-kernel@...r.kernel.org>
Subject: serial 8250, sysrq, and break

I'm trying to figure out if an issue I'm having with sysrq (more  
likely with receiving a BREAK) is a HW issue or software.

If I have a lot of spew in the kernel (like a printk in receive_chars 
()) sysrq seems to work properly, in that the character sent after  
the break is properly received.  However, if I don't have any spew  
the character after the break than I get the wrong character:

[   22.607920] SysRq : in __sysrq_get_key_op key:255
[   34.856712] SysRq : in __sysrq_get_key_op key:255
[   44.823519] SysRq : in __sysrq_get_key_op key:252
[   51.306161] SysRq : in __sysrq_get_key_op key:240
[   60.947047] SysRq : in __sysrq_get_key_op key:252
[   65.942674] SysRq : in __sysrq_get_key_op key:128
[  102.251461] SysRq : in __sysrq_get_key_op key:254

It seems like hw is treating part of the break as a valid received  
character.  But, wanted to see if there were any ideas before I  
consider this a HW issue.

- k
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