netdev - Re: [RFC net-next] net: stmmac: should not modify RX descriptor when STMMAC resume

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Message-ID: <bd184c72-7b12-db4c-0dd3-25f0fd45b7aa@nvidia.com>
Date:   Thu, 22 Apr 2021 19:18:53 +0100
From:   Jon Hunter <jonathanh@...dia.com>
To:     Florian Fainelli <f.fainelli@...il.com>,
        Joakim Zhang <qiangqing.zhang@....com>,
        "peppe.cavallaro@...com" <peppe.cavallaro@...com>,
        "alexandre.torgue@...s.st.com" <alexandre.torgue@...s.st.com>,
        "joabreu@...opsys.com" <joabreu@...opsys.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "mcoquelin.stm32@...il.com" <mcoquelin.stm32@...il.com>,
        "andrew@...n.ch" <andrew@...n.ch>
CC:     dl-linux-imx <linux-imx@....com>,
        "treding@...dia.com" <treding@...dia.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [RFC net-next] net: stmmac: should not modify RX descriptor when
 STMMAC resume


On 22/04/2021 18:32, Florian Fainelli wrote:
> 
> 
> On 4/22/2021 10:00 AM, Jon Hunter wrote:
>>
>> On 22/04/2021 17:12, Florian Fainelli wrote:
>>
>> ...
>>
>>> What does the resumption failure looks like? Does the stmmac driver
>>> successfully resume from your suspend state, but there is no network
>>> traffic? Do you have a log by any chance?
>>
>> The board fails to resume and appears to hang. With regard to the
>> original patch I did find that moving the code to re-init the RX buffers
>> to before the PHY is enabled did work [0].
> 
> You indicated that you are using a Broadcom PHY, which specific PHY are
> you using?
> 
> I suspect that the stmmac is somehow relying on the PHY to provide its
> 125MHz RXC clock back to you in order to have its RX logic work correctly.
> 
> One difference between using the Broadcom PHY and the Generic PHY
> drivers could be whether your Broadcom PHY driver entry has a
> .suspend/.resume callback implemented or not.


This board has a BCM89610 and uses the drivers/net/phy/broadcom.c
driver. Interestingly I don't see any suspend/resume handlers for this phy.

Cheers
Jon

-- 
nvpublic