netdev - Re: [PATCH] ravb: add wake-on-lan support via magic packet

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Date:   Fri, 12 May 2017 16:32:42 +0200
From:   "Niklas Söderlund" <niklas.soderlund@...natech.se>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>
Subject: Re: [PATCH] ravb: add wake-on-lan support via magic packet

Hi Geert,

On 2017-05-12 14:58:53 +0200, Niklas Söderlund wrote:
> Hi Geert,
> 
> Thanks for testing.
> 
> On 2017-05-12 14:47:53 +0200, Geert Uytterhoeven wrote:
> > Hi Niklas,
> > 
> > On Fri, May 12, 2017 at 12:27 AM, Niklas Söderlund
> > <niklas.soderlund+renesas@...natech.se> wrote:
> > > WoL is enabled in the suspend callback by setting MagicPacket detection
> > > and disabling all interrupts expect MagicPacket. In the resume path the
> > > driver needs to reset the hardware to rearm the WoL logic, this prevents
> > > the driver from simply restoring the registers and to take advantage of
> > > that ravb was not suspended to reduce resume time. To reset the
> > > hardware the driver closes the device, sets it in reset mode and reopens
> > > the device just like it would do in a normal suspend/resume scenario
> > > without WoL enabled, but it both closes and opens the device in the
> > > resume callback since the device needs to be reset for WoL to work.
> > >
> > > One quirk needed for WoL is that the module clock needs to be prevented
> > > from being switched off by Runtime PM. To keep the clock alive the
> > > suspend callback need to call clk_enable() directly to increase the
> > > usage count of the clock. Then when Runtime PM decreases the clock usage
> > > count it won't reach 0 and be switched off.
> > >
> > > Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@...natech.se>
> > 
> > Thanks for your patch!
> > 
> > Wake-on-LAN now works for me on Salvator-X (both H3 and M3).
> > 
> > However, after a few cycles, Ethernet stopped working, because CMA ran out of
> > memory:
> > 
> >     cma: cma_alloc: alloc failed, req-size: 6 pages, ret: -4
> >     dpm_run_callback(): ravb_resume+0x0/0x148 returns -12
> >     PM: Device e6800000.ethernet failed to resume: error -12
> > 
> > Are we still missing some ravb patches in net-next, or is this a different
> > issue?
> 
> Interesting, I did a 100 loop test on H3 based on v4.11 without any 
> issues. What are you using as a base for your test and I will test if I 
> can reproduce it.

I re-ran my test based on renesas-drivers-2017-05-02-v4.11 using the 
arm64 defconfig. And was not able to see this :-(

My TC is basically a expect script that do:

ethtool -s eth0 wol g

for (i = 0; i < 100; i++) {
    echo s2idle > /sys/power/mem_sleep
    echo mem > /sys/power/state

    sleep 5

    HOST: etherwake -i net0 2e:09:0a:00:83:90

    WAIT_FOR_CONSOLE
}

I use the default DT and arm64 defconfig and no other modifications. I'm 
testing on H3 ES1.x board. What can be the different for us?

> 
> > 
> > When using PSCI suspend/resume, and Wake-on-LAN cannot work due to
> > PSCI firmware issues, Ethernet fails to come up afterwards:
> > 
> >     ravb e6800000.ethernet eth0: failed to switch device to config mode
> >     ravb e6800000.ethernet eth0: device will be stopped after h/w
> > processes are done.
> >     ravb e6800000.ethernet eth0: failed to switch device to config mode
> >     dpm_run_callback(): ravb_resume+0x0/0x148 returns -110
> >     PM: Device e6800000.ethernet failed to resume: error -110
> > 
> > Your resume routine cannot assume RAVB is in a sane mode, as it will
> > have been reset if PSCI suspend was used.
> 
> Ouch, yes this is true thanks for reporting will look in to it.
> 
> The problem is that in the resume handler if WoL is enabled it will try 
> to close the device before reinitializing it from reset state. If WoL is 
> not enabled the device will be closed at suspend time so no need to 
> close it before restoring operation from reset in the resume handler.

I was not able to reproduce this fault neither :-( But here I see 
something is wrong, nothing is outputted on the console if WoL is 
enabled:

echo 0 > /sys/module/printk/parameters/console_suspend
i2cset -f -y 7 0x30 0x20 0x0F
<Flip SW23>
echo mem > /sys/power/state
<Flip SW23>
<System wakes up>

While:
ethtool -s eth0 wol g
echo 0 > /sys/module/printk/parameters/console_suspend
i2cset -f -y 7 0x30 0x20 0x0F
<Flip SW23>
echo mem > /sys/power/state
<Flip SW23>
<Nothing happens on the console, not even firmware info is printed>

Are you enabling anything else then console_suspend to be able to 
capture output at this point? I'm using the same setup tag and config as 
I described above.

> 
> > 
> > Gr{oetje,eeting}s,
> > 
> >                         Geert
> > 
> > --
> > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
> > 
> > In personal conversations with technical people, I call myself a hacker. But
> > when I'm talking to journalists I just say "programmer" or something like that.
> >                                 -- Linus Torvalds
> 
> -- 
> Regards,
> Niklas Söderlund

-- 
Regards,
Niklas Söderlund