CVS commit: src/sys/dev/pci

["SAITOH Masanobu" <msaitoh%netbsd.org@localhost>]

Module Name:    src
Committed By:   msaitoh
Date:           Wed Oct 20 08:06:45 UTC 2021

Modified Files:
        src/sys/dev/pci: if_wm.c

Log Message:
Disable printf()s in wm_flush_desc_rings() because the code is verified.

 The problem was very rare, so I added those printf()s as we can see.
Last week, knakahara and I found a procedure to reproduce the problem and
verified it worked correctly.

 To reproduce the problem:

 0) Use I219 V1 to V5. Not all of them have the problem and newer than V5 may
    have the problem. I used V2 for the test.
 1) Define WM_DEBUG or add printf in wm_flush_desc_rings() to see
    DESCRING_STATUS_FLUSH_REQ bit.
 2) Run "iperf -s" on the DUT.
 3) Run "iperf3 -R -u -c 192.168.1.110 -w 8m -b 1g" repeatedly on another
    machine. Note that kern.sbmax should be increased on both machines.
 4) run
        while true; do
        ifconfig wm0 down up
        sleep 30
        done
 5) After DESCRING_STATUS_FLUSH_REQ is set, without wm_flush_desc_rings(),
    TX stalls and reboot is required to recover from it.
    With wm_flush_desc_rings(), no device hang.
 6) If you can't see the DESCRING_STATUS_FLUSH_REQ is set, change the media
    to 100BASE-T.

 Note that if_wm.c rev. 1.710 originally written by chuq is required for the
test. Without the change, the device becomes unrecoverable state before
wm_flush_desc_rings() and the function doesn't recover from the problem.


To generate a diff of this commit:
cvs rdiff -u -r1.713 -r1.714 src/sys/dev/pci/if_wm.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.