[#5145] SPORT UART hits underflow when flooding

Submitted By: Claudio Cunha

Open Date

2009-05-19 08:06:35 Close Date

2010-06-11 04:44:54

Priority:

Medium Assignee:

Sonic Zhang

Status:

Closed Fixed In Release:

N/A

Found In Release:

2009R1-RC6 Release:

2.6.28.9

Category:

Drivers Board:

EZKIT Lite

Processor:

BF533 Silicon Revision:

Is this bug repeatable?:

Yes Resolution:

Fixed

Uboot version or rev.:

Toolchain version or rev.:

4.1.2

App binary format:

N/A

Summary: SPORT UART hits underflow when flooding

Details:

Hi,

I've reported a bug when we make the link ppp as described in the document

http://docs.blackfin.uclinux.org/doku.php?id=uclinux-dist:ppp in the lauching pppd part.

If I make a ping -f -s 1500 10.0.0.209, a SPORT Error: RX underflow appears, but in the other side (ping -f -s 1500 10.0.0.2) there is no problem.

Look at the file jointed.

Best regards,

Claudio

Follow-ups

--- Mike Frysinger 2009-05-19 08:13:11

please describe your exact hardware setup

--- Claudio Cunha 2009-05-19 08:27:59

It's a board very similar to the Blackfin BF533 Ez-Kit, with sport emulated

uart. And I use the sport0 at 57600 bauds, in the other side there is a pc linux

with usb-serial converter...

--- Mike Frysinger 2009-05-19 08:32:40

forget about ppp/ping. try a simple case like sending/receiving /proc/kallsyms

over the SPORT UART and make sure that works first.

--- maverick gao 2009-05-27 04:23:09

Yes, I meet this problem too. I wrote it in the forum.

https://blackfin.uclinux.org/gf/project/uclinux-dist/forum/?_forum_action=ForumMessageBrowse&thread_id=34102&action=ForumBrowse&forum_id=39

--- Sonic Zhang 2009-05-27 05:18:57

Confirmed in SVN trunk.

--- maverick gao 2009-05-29 21:34:23

What does it mean that Confirmed in SVN trunk

--- maverick gao 2009-05-30 21:52:44

I made a mistake that my linux kernel is not 2.4.

It is 2.6.16.11-ADI-2006R1-hhbf and gcc is 3.4.5

processor is BF531, silicon version is 0.5

--- Sonic Zhang 2009-05-31 02:22:54

That means we can replicated it with SVN trunk souce and blackfin developing

board.

--- Sonic Zhang 2009-06-18 06:43:25

This bug is found to occur only when we set sport RX word length to 17 ~ 32

bits.

The walkaround by now is warning customer not to use 8-bit uart mode in sport

uart driver. Use 7, 6, 5 bit mode instead.

--- Mike Frysinger 2009-06-18 07:07:52

unless i missed something, CS8 is the default and most common mode people will

be using. telling people not to use it isnt really a workaround.

--- Sonic Zhang 2009-06-18 23:03:50

CS8 can be replaced by 2 CS5 transfer. There is no walk around in CS8 mode.

--- Sonic Zhang 2009-07-17 06:32:57

Disable local interrupt to walk around the fake RX underflow error

when do 32-bit reading from RX fifois interrupted by other interrupt.

This is a possible hardware anomaly. After it is logged officially,

the official anomaly id should be listed bellow.

16-bit reading is not affected.

--- Robin Getz 2010-06-11 14:00:44

FYI:

Now described in the anomaly sheets now:

Anomaly 05000473 - Interrupted SPORT Receive Data Register Read Results In

Underflow when SLEN > 15

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