Flow-control representation in ethtool (mii.c fix?)

[artpol <artpol84@gmail.com>]

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Hello, All.

I was dealing with flow-control on my ethernet card:
eth0: RTL8168d/8111d 
# uname -r
2.6.35-28-generic-pae (Ubuntu 10.10 current kernel)

And found following problem:

~# ethtool eth0
Settings for eth0:
Supported ports: [ TP MII ]
Supported link modes:   10baseT/Half 10baseT/Full 
                        100baseT/Half 100baseT/Full 
                        1000baseT/Half 1000baseT/Full 
Supports auto-negotiation: Yes
Advertised link modes:  10baseT/Half 10baseT/Full 
                        100baseT/Half 100baseT/Full 
                        1000baseT/Half 1000baseT/Full 
Advertised pause frame use: No
...
Link partner advertised pause frame use: No

As you can see no pause frame is advertised. But mii-tool shows
different result:
~# mii-tool eth0
eth0: negotiated 100baseTx-FD flow-control, link ok

And the same shows remote embedded device whith which I work.

Inspection of kernel sources shows that GSET ethtool command leads
r8169.c to call mii_ethtool_gset(). And looking there I found that this
function simply ignore Pause-related settings. Searching kernel sources
shows that a lot of ethernet drivers use this function 
(grep -R mii_ethtool_gset drivers/net/*)

In latest kernel (2.6.38.4) I also see that this thing doesn't fixed. So
I'd like to know is there some background behind this current design or
not. If not I suggest simple patch attached to this mail. I've test it
on kernel 2.6.38.4 and it works for me:

Settings for eth0:
  Supported ports: [ TP MII ]
  Supported link modes:   10baseT/Half 10baseT/Full
                          100baseT/Half 100baseT/Full
                          1000baseT/Half 1000baseT/Full
  Supports auto-negotiation: Yes
  Advertised link modes:  10baseT/Half 10baseT/Full
                          100baseT/Half 100baseT/Full
                          1000baseT/Half 1000baseT/Full
  Advertised pause frame use: Symmetric Receive-only
  Advertised auto-negotiation: Yes
  Link partner advertised link modes:  10baseT/Half 10baseT/Full
                                       100baseT/Half 100baseT/Full
  Link partner advertised pause frame use: Symmetric
  Link partner advertised auto-negotiation: Yes
....

--
Artem Polyakov.

[-- Attachment #2: mii_flow_control_gset.patch --]
[-- Type: text/x-patch, Size: 532 bytes --]

diff -Naur linux-2.6.38.4_old/drivers/net/mii.c linux-2.6.38.4_new/drivers/net/mii.c
--- linux-2.6.38.4_old/drivers/net/mii.c	2011-04-22 04:34:46.000000000 +0700
+++ linux-2.6.38.4_new/drivers/net/mii.c	2011-04-25 22:55:40.342981965 +0700
@@ -49,6 +49,10 @@
 		result |= ADVERTISED_100baseT_Half;
 	if (advert & ADVERTISE_100FULL)
 		result |= ADVERTISED_100baseT_Full;
+	if (advert & ADVERTISE_PAUSE_CAP)
+		result |= ADVERTISED_Pause;
+	if (advert & ADVERTISE_PAUSE_ASYM)
+		result |= ADVERTISED_Asym_Pause;
 
 	return result;
 }