Messages in this thread | | | Subject | Re: [PATCH net 1/1] net: stmmac: fix MAC and phylink mismatch issue after resume with STMMAC_FLAG_USE_PHY_WOL enabled | From | Paolo Abeni <> | Date | Thu, 09 Nov 2023 13:13:55 +0100 |
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On Thu, 2023-11-09 at 09:15 +0000, Russell King (Oracle) wrote: > 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.
@Gan Yi Fang: at very least we need a solid explanation in the commit message why this change don't cause the above problems.
Thanks,
Paolo
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