Re: [PATCH net 1/1] net: stmmac: fix MAC and phylink mismatch issue after resume with STMMAC_FLAG_USE_PHY_WOL enabled

From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Gan Yi Fang <yi.fang.gan@intel.com>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>,
	Jose Abreu <joabreu@synopsys.com>,
	"David S . Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Maxime Coquelin <mcoquelin.stm32@gmail.com>,
	Joakim Zhang <qiangqing.zhang@nxp.com>,
	netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Looi Hong Aun <hong.aun.looi@intel.com>,
	Voon Weifeng <weifeng.voon@intel.com>,
	Song Yoong Siang <yoong.siang.song@intel.com>
Subject: Re: [PATCH net 1/1] net: stmmac: fix MAC and phylink mismatch issue after resume with STMMAC_FLAG_USE_PHY_WOL enabled
Date: Thu, 9 Nov 2023 09:15:36 +0000	[thread overview]
Message-ID: <ZUyjOEQHHnnbzwrV@shell.armlinux.org.uk> (raw)
In-Reply-To: <20231109050027.2545000-1-yi.fang.gan@intel.com>

On Thu, Nov 09, 2023 at 01:00:27PM +0800, Gan Yi Fang wrote:
> From: "Gan, Yi Fang" <yi.fang.gan@intel.com>
> 
> The issue happened when flag STMMAC_FLAG_USE_PHY_WOL is enabled.
> It can be reproduced with steps below:
> 1. Advertise only one speed on the host
> 2. Enable the WoL on the host
> 3. Suspend the host
> 4. Wake up the host
> 
> When the WoL is disabled, both the PHY and MAC will suspend and wake up
> with everything configured well. When WoL is enabled, the PHY needs to be
> stay awake to receive the signal from remote client but MAC will enter
> suspend mode.
> 
> When the MAC resumes from suspend, phylink_resume() will call
> phylink_start() to start the phylink instance which will trigger the
> phylink machine to invoke the mac_link_up callback function. The
> stmmac_mac_link_up() will configure the MAC_CTRL_REG based on the current
> link state. Then the stmmac_hw_setup() will be called to configure the MAC.
> 
> This sequence might cause mismatch of the link state between MAC and
> phylink. This patch moves the phylink_resume() after stmamc_hw_setup() to
> ensure the MAC is initialized before phylink is being configured.

Isn't this going to cause problems?

stmamc_hw_setup() calls stmmac_init_dma_engine(), which then calls
stmmac_reset() - and stmmac_reset() can fail if the PHY clock isn't
running, which is why phylink_resume() gets called before this.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel