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

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Date:   Fri, 12 May 2017 15:03:15 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Niklas Söderlund <niklas.soderlund@...natech.se>
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 Niklas,

On Fri, May 12, 2017 at 2:58 PM, Niklas Söderlund
<niklas.soderlund@...natech.se> 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.

Something based on last renesas-drivers.

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