The following reply was made to PR kern/29731; it has been noted by GNATS.

From: Dan Ellis <dellis@conexant.com>
To: gnats-bugs@netbsd.org
Cc: kern-bug-people@netbsd.org, netbsd-bugs@netbsd.org,
	gnats-admin@netbsd.org
Subject: Re: kern/29731: ehci driver erroneously reports IO errors
Date: Mon, 18 Apr 2005 10:45:50 +0100

     dan@pod51.demon.co.uk wrote:
     > A suitable fix would be to alter line 833 (of revision 1.91) to say:
     >
     > if (status & EHCI_QTD_HALTED) {
 
 
     This fix seems wrong given that the HALTED bit can be masked
     away on line 801.
     I'm curious, what are the errors that you have observed that
     the host controller recovers from?
 
 
 Line 801 only masks HALTED if it's the last one and complete, not for 
 intermediate transfers or short reads.
 
 The host controller can recover from up to 3 errors on a given 
 transaction. We are developing some hardware which was causing a lot of 
 XACTER and BUFERR errors, but they were getting through with the 
 hardware retries.
 
 I suspect the error rate in normal operation is not absolutely zero - 
 there is quite possibly the odd transaction which has an error and has 
 to get retried, but halting the pipe just because there was a retry 
 could be a bit terminal.
 
 If a transfer is not marked as NORMAL_COMPLETION when it has only 
 suffered retries,. then further up the stack, it doesn't complete 
 properly, especially if it is marked as IOERROR.
 
 -- 
 Daniel Ellis                     Conexant Systems Ltd
 Senior Software Engineer         Unit 230 Cambridge Science Park
 http://www.conexant.com          Milton Road
 Phone: +44 1223 707318           Cambridge  CB4 0WB
 Fax:   +44 1223 707447           UK
 
 
 
 
 
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