netdev - Re: stmmac / meson8b-dwmac

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Message-ID: <e009cbbb-e31d-2438-e454-2fa10ebec542@gmx.de>
Date:   Thu, 21 Feb 2019 20:34:51 +0100
From:   Simon Huelck <simonmail@....de>
To:     Jerome Brunet <jbrunet@...libre.com>,
        Jose Abreu <jose.abreu@...opsys.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc:     linux-amlogic@...ts.infradead.org, Gpeppe.cavallaro@...com,
        alexandre.torgue@...com,
        Emiliano Ingrassia <ingrassia@...genesys.com>,
        netdev@...r.kernel.org
Subject: Re: stmmac / meson8b-dwmac

Am 21.02.2019 um 18:46 schrieb Jerome Brunet:
> On Thu, 2019-02-21 at 18:27 +0100, Simon Huelck wrote:
>> Hi,
>>
>>
>>
>> this was changed recently, with a patch for the EEE stuff , see here:
>>
>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.0-rc7&id=e35e26b26e955c53e61c154ba26b9bb15da6b858
> Hu, I was not aware this finally went through. Good !
> As explained in the patch and by Jose, the GMAC should be using IRQ_LEVEL.
>
> The realtek PHY has EEE enabled by default. Having this enabled generates a
> lot of (Low Power) Interrupts.
>
> Previously, when the GMAC used IRQ_EDGE. Because it is wrong, we would
> eventually miss an IRQ and the interface would just die. Unfortunately, it was
> not that easy find out.
>
> 2 years ago, we just noticed that disabling EEE would make the failure go
> away. Forcing this EEE feature off through DT was merely a work around.
>
> Now that the real cause of the problem is known, there is no reason to keep
> this hack around.
>
> Whether EEE adds a performance penality and why, is another topic.
> As Jose pointed out, you can disable EEE at runtime, using ethtool.
>
> Jerome
>
Hi,



i disabled EEE via ethtool and via the .dtb , but the performance
penalty stays. Kernel 4.14 still gives me the former "good" performance.



regards,

Simon