[Intel-wired-lan] [PATCH] igb: Remove superfluous reset to PHY and page 0 selection

[Brown, Aaron F]

> From: Intel-wired-lan [mailto:intel-wired-lan-bounces at osuosl.org] On Behalf
> Of Grönke, Christian
> Sent: Tuesday, June 26, 2018 3:12 AM
> To: intel-wired-lan at lists.osuosl.org
> Cc: Chris J Arges <christopherarges at gmail.com>
> Subject: [Intel-wired-lan] [PATCH] igb: Remove superfluous reset to PHY and
> page 0 selection
> 
> This patch reverts two previous applied patches to fix an issue
> that appeared when using SGMII based SFP modules. In the current
> state the driver will try to reset the PHY before obtaining the
> phy_addr of the SGMII attached PHY. That leads to an error in
> e1000_write_phy_reg_sgmii_82575. Causing the initialization to
> fail:
> 
>     igb: Intel(R) Gigabit Ethernet Network Driver - version 5.4.0-k
>     igb: Copyright (c) 2007-2014 Intel Corporation.
>     igb: probe of ????:??:??.? failed with error -3
> 
> The patches being reverted are:
> 
>     commit 182785335447957409282ca745aa5bc3968facee
>     Author: Aaron Sierra <asierra at xes-inc.com>
>     Date:   Tue Nov 29 10:03:56 2016 -0600
> 
>         igb: reset the PHY before reading the PHY ID
> 
>     commit 440aeca4b9858248d8f16d724d9fa87a4f65fa33
>     Author: Matwey V Kornilov <matwey at sai.msu.ru>
>     Date:   Thu Nov 24 13:32:48 2016 +0300
> 
>          igb: Explicitly select page 0 at initialization
> 
> The first reverted patch directly causes the problem mentioned above.
> In case of SGMII the phy_addr is not known at this point and will
> only be obtained by 'igb_get_phy_id_82575' further down in the code.
> The second removed patch selects forces selection of page 0 in the
> PHY. Something that the reset tries to address as well.
> 
> As pointed out by Alexander Duzck, the patch below fixes the same
> issue but in the proper location:
> 
>     commit 4e684f59d760a2c7c716bb60190783546e2d08a1
>     Author: Chris J Arges <christopherarges at gmail.com>
>     Date:   Wed Nov 2 09:13:42 2016 -0500
> 
>         igb: Workaround for igb i210 firmware issue
> 
> Reverts: 440aeca4b9858248d8f16d724d9fa87a4f65fa33.
> Reverts: 182785335447957409282ca745aa5bc3968facee.
> 
> Signed-off-by: Christian Grönke <c.groenke at infodas.de>
> ---
>  e1000_82575.c |   12 ------------
>  1 file changed, 12 deletions(-)

Tested-by: Aaron Brown <aaron.f.brown at intel.com>