netdev - RE: [PATCH 1/1] ixgbe: add fiber tranceiver plug/unplug notifier

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Date:	Thu, 16 Jun 2016 17:46:36 +0000
From:	"Skidmore, Donald C" <donald.c.skidmore@...el.com>
To:	zhuyj <zyjzyj2000@...il.com>,
	"e1000-devel@...ts.sourceforge.net" 
	<e1000-devel@...ts.sourceforge.net>,
	netdev <netdev@...r.kernel.org>
Subject: RE: [PATCH 1/1] ixgbe: add fiber tranceiver plug/unplug notifier



From: zhuyj [mailto:zyjzyj2000@...il.com] 
Sent: Thursday, June 16, 2016 3:43 AM
To: e1000-devel@...ts.sourceforge.net; netdev <netdev@...r.kernel.org>; Skidmore, Donald C <donald.c.skidmore@...el.com>
Cc: Zhu Yanjun <zyjzyj2000@...il.com>
Subject: Re: [PATCH 1/1] ixgbe: add fiber tranceiver plug/unplug notifier

Sorry, Maybe last_tranceiver_status and tranceiver_polltime should not be in ixgbe_hw struct. It is better in ixgbe struct. I will change it soon.

Zhu Yanjun

On Wed, Jun 15, 2016 at 9:36 PM, <zyjzyj2000@...il.com> wrote:
From: Zhu Yanjun <zyjzyj2000@...il.com>

When the fiber tranceiver is plugged/unplugged, a netdev notifier is
 sent. The userspace tools or kernel can receive this notifier.

Signed-off-by: Zhu Yanjun <zyjzyj2000@...il.com>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c |   24 +++++++++++++++++++++++-
 drivers/net/ethernet/intel/ixgbe/ixgbe_type.h |    2 ++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 088c47c..1d8c1ff 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -5635,6 +5635,8 @@ static int ixgbe_sw_init(struct ixgbe_adapter *adapter)
        hw->revision_id = pdev->revision;
        hw->subsystem_vendor_id = pdev->subsystem_vendor;
        hw->subsystem_device_id = pdev->subsystem_device;
+       hw->last_tranceiver_status = IXGBE_NOT_IMPLEMENTED;
+       hw->tranceiver_polltime = 0;

        /* Set common capability flags and settings */
        rss = min_t(int, ixgbe_max_rss_indices(adapter), num_online_cpus());
@@ -7067,7 +7069,27 @@ static void ixgbe_watchdog_subtask(struct ixgbe_adapter *adapter)
 static void ixgbe_sfp_detection_subtask(struct ixgbe_adapter *adapter)
 {
        struct ixgbe_hw *hw = &adapter->hw;
-       s32 err;
+       s32 err, status;
+
+       if ((hw->mac.ops.get_media_type(hw) == ixgbe_media_type_fiber) &&
+           time_after(jiffies, hw->tranceiver_polltime)) {
+               status = IXGBE_READ_REG(hw, IXGBE_ESDP) & IXGBE_ESDP_SDP2;
+               if (status != hw->last_tranceiver_status) {
+                       unsigned long val;
+
+                       if (!status) {
+                               hw->phy.sfp_type = ixgbe_sfp_type_not_present;
+                               val = NETDEV_FIBER_TRANCEIVER_UNPLUG;
+                       } else {
+                               val = NETDEV_FIBER_TRANCEIVER_PLUG;
+                       }
+                       rtnl_lock();
+                       call_netdevice_notifiers(val, adapter->netdev);
+                       rtnl_unlock();
+               }
+               hw->last_tranceiver_status = status;
+               hw->tranceiver_polltime = jiffies + 3 * HZ;
+       }

        /* If crosstalk fix enabled verify the SFP+ cage is full */
        if (adapter->need_crosstalk_fix) {
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_type.h b/drivers/net/ethernet/intel/ixgbe/ixgbe_type.h
index da3d835..fe19899 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_type.h
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_type.h
@@ -3525,6 +3525,8 @@ struct ixgbe_hw {
        bool                            force_full_reset;
        bool                            allow_unsupported_sfp;
        bool                            wol_enabled;
+       s32                             last_tranceiver_status;
+       unsigned long                   tranceiver_polltime;
 };

 struct ixgbe_info {
--
1.7.9.5


What exactly is this information (arrival/removal of a SFP+ module) needed for?  I can't think of any use the kernel would have, outside the driver.  So I must assume a userspace application, if so what is it?

Top that off this notification would only be actuate while the port was up, which limits its value even further.  The driver just doesn't bother keeping this information unless it is needed.   With these limitations I'm not seeing the advantage of adding this.

Also what a given SDP is connected to different for different HW types so assumptions made in the patch above would be incorrect on various platforms.

-Don Skidmore <donald.c.skidmore@...el.com>