netdev - Re: [PATCH net-next 9/9] net: stmmac: convert to phylink managed EEE support

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Message-ID: <fd4af708-0c92-4295-9801-bf53db3a16cc@nvidia.com>
Date: Wed, 19 Feb 2025 20:05:57 +0000
From: Jon Hunter <jonathanh@...dia.com>
To: "Russell King (Oracle)" <linux@...linux.org.uk>
Cc: Andrew Lunn <andrew@...n.ch>, Heiner Kallweit <hkallweit1@...il.com>,
 Alexandre Torgue <alexandre.torgue@...s.st.com>,
 Andrew Lunn <andrew+netdev@...n.ch>,
 Bryan Whitehead <bryan.whitehead@...rochip.com>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, linux-arm-kernel@...ts.infradead.org,
 linux-stm32@...md-mailman.stormreply.com,
 Marcin Wojtas <marcin.s.wojtas@...il.com>,
 Maxime Coquelin <mcoquelin.stm32@...il.com>, netdev@...r.kernel.org,
 Paolo Abeni <pabeni@...hat.com>, UNGLinuxDriver@...rochip.com,
 "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH net-next 9/9] net: stmmac: convert to phylink managed EEE
 support

On 19/02/2025 19:13, Russell King (Oracle) wrote:
> On Wed, Feb 19, 2025 at 05:52:34PM +0000, Jon Hunter wrote:
>> On 19/02/2025 15:36, Russell King (Oracle) wrote:
>>> So clearly the phylink resolver is racing with the rest of the stmmac
>>> resume path - which doesn't surprise me in the least. I believe I raised
>>> the fact that calling phylink_resume() before the hardware was ready to
>>> handle link-up is a bad idea precisely because of races like this.
>>>
>>> The reason stmmac does this is because of it's quirk that it needs the
>>> receive clock from the PHY in order for stmmac_reset() to work.
>>
>> I do see the reset fail infrequently on previous kernels with this device
>> and when it does I see these messages ...
>>
>>   dwc-eth-dwmac 2490000.ethernet: Failed to reset the dma
>>   dwc-eth-dwmac 2490000.ethernet eth0: stmmac_hw_setup: DMA engine
>>    initialization failed
> 
> I wonder whether it's also racing with phylib, but phylink_resume()
> calling phylink_start() going in to call phy_start() is all synchronous.
> That causes __phy_resume() to be called.
> 
> Which PHY device/driver is being used?

Looks like it is this Broadcom driver ...

  Broadcom BCM89610 stmmac-0:00: phy_eee_rx_clock_stop: clk_stop_enable 1

Thanks
Jon

-- 
nvpublic