Message-ID: <20170512211222.GI31437@bigcity.dyn.berto.se>
Date:   Fri, 12 May 2017 23:12:22 +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 16:43:55 +0200, Geert Uytterhoeven wrote:
> Hi Niklas,
> 
> On Fri, May 12, 2017 at 4:32 PM, Niklas Söderlund
> <niklas.soderlund@...natech.se> wrote:
> > On 2017-05-12 14:58:53 +0200, Niklas Söderlund wrote:
> >> On 2017-05-12 14:47:53 +0200, Geert Uytterhoeven wrote:
> >> > 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?
> 
> I'm not using "echo s2idle > /sys/power/mem_sleep", as renesas-drivers still
> has my patches to not use PSCI suspend if any other wake-up sources
> are configured.
> 
> I'll retry later...
> 
> >> > 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.
> 
> With renesas-drivers, it will refuse to use PSCI suspend if any other wake-up
> sources are configured, i.e. try
> 
>     echo disabled > /sys/devices/platform/soc/e6800000.ethernet/power/wakeup
> 
> Good luck, and have a nice weekend!

Thanks this allowed me to reproduce the same error as you. And after 
future digging I don't believe the problem being in the logic of the 
ravb suspend/resume functions. The problem is that the module clock is 
never turned on after PCSI system suspend if its usage count is above 0 
at suspend time, so the errors we both now observe are due to the module 
clock being disabled.

If I set DEBUG in renesas-cpg-mssr.c and observe when each module clock 
is turned OFF and ON, the fault is clear. If WoL is enabled the clock is 
never turned on when the system is resuming, while if WoL is disabled it 
is. I verified this by removing the calls to clk_enable() and 
clk_disable() from this patch, and by doing so the PCSI system suspend 
works perfect with WoL enabled and the ravb comes up fine after toggling 
SW23 (while ofc WoL no longer works in s2idle due to the module clock is 
switched off at suspend time).

I checked drivers/clk/renesas and I can't find a suspend/resume handler 
for the clock driver, how is this intended to work? If a clock have a 
usage count higher then 0 when the system is PSCI System Suspended it 
seems like it won't be turned back on when the system is resumed from 
this sleep stage. I might have misunderstood something and I need to 
alter the logic in the ravb driver to let the clock driver know it 
should turn on the clock at resume time?

Whit all this being said I still like to withdraw this patch as I found 
another fault with it, ravb_wol_restore() will unconditionally be called 
while ravb_wol_setup() will only be called if netif_running(ndev). This 
is en easy fix and I will send out a v2 once we figure out what to do 
about the clock.

> 
> 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

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