netdev - Re: RTL8402 stops working after hibernate/resume

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Date:   Tue, 29 Sep 2020 22:29:18 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Petr Tesarik <ptesarik@...e.cz>,
        Heiner Kallweit <hkallweit1@...il.com>
Cc:     Realtek linux nic maintainers <nic_swsd@...ltek.com>,
        netdev@...r.kernel.org, linux-clk@...r.kernel.org
Subject: Re: RTL8402 stops working after hibernate/resume

p.s.

On 9/29/20 10:08 PM, Hans de Goede wrote:

<snip>

> So I believe that the proper fix for this is to revert
> commit 9f0b54cd167219
> ("r8169: move switching optional clock on/off to pll power functions")

Heiner, assuming you agree that reverting this commit is
the best way to fix this, can you please submit a revert
for this upstream ?

With a:

Fixes: 9f0b54cd167219 ("r8169: move switching optional clock on/off to pll power functions")

Tag in the commit-message so that this gets cherry-picked into
the stable series where necessary.

Regards,

Hans



> As that caused the whole chip's clock to be left off after
> a suspend/resume while the interface is down.
> 
> Also some remarks about this while I'm being a bit grumpy about
> all this anyways (sorry):
> 
> 1. 9f0b54cd167219 ("r8169: move switching optional clock on/off
> to pll power functions") commit's message does not seem to really
> explain why this change was made...
> 
> 2. If a git blame would have been done to find the commit adding
> the clk support: commit c2f6f3ee7f22 ("r8169: Get and enable optional ether_clk clock")
> then you could have known that the clk in question is an external
> clock for the entire chip, the commit message pretty clearly states
> this (although "the entire" part is implied only) :
> 
> "On some boards a platform clock is used as clock for the r8169 chip,
> this commit adds support for getting and enabling this clock (assuming
> it has an "ether_clk" alias set on it).
> 
> This is related to commit d31fd43c0f9a ("clk: x86: Do not gate clocks
> enabled by the firmware") which is a previous attempt to fix this for some
> x86 boards, but this causes all Cherry Trail SoC using boards to not reach
> there lowest power states when suspending.
> 
> This commit (together with an atom-pmc-clk driver commit adding the alias)
> fixes things properly by making the r8169 get the clock and enable it when
> it needs it."
> 
> Regards,
> 
> Hans