> -----Original Message----- > From: Andrew Lunn <andrew@xxxxxxx> > Sent: 2022年8月18日 9:20 > To: Wei Fang <wei.fang@xxxxxxx> > Cc: hkallweit1@xxxxxxxxx; linux@xxxxxxxxxxxxxxx; davem@xxxxxxxxxxxxx; > edumazet@xxxxxxxxxx; kuba@xxxxxxxxxx; pabeni@xxxxxxxxxx; > robh+dt@xxxxxxxxxx; krzysztof.kozlowski+dt@xxxxxxxxxx; f.fainelli@xxxxxxxxx; > netdev@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; > linux-kernel@xxxxxxxxxxxxxxx > Subject: Re: [PATCH net 1/2] dt: ar803x: Document disable-hibernation > property > > > Hi Andrew, > > > > Your suggestion is indeed an effective solution, but I checked both > > the datasheet and the driver of AR803x PHYs and found that the > > qca,clk-out-frequency and the qca,keep-pll-enabled properties are associated > with the CLK_25M pin of AR803x PHYs. > > But there is a case that CLK_25M pin is not used on some platforms. > > Taking our i.MX8DXL platform as an example, the stmmac and AR8031 PHY > > are applied on this platform, but the CLK_25M pin of AR8031 is not > > used. So when I used the method you mentioned above, it did not work > > as expected. In this case, we can only disable the hibernation mode of > > AR803x PHYs and keep the RX_CLK always outputting a valid clock so that the > stmmac can complete the software reset operation. > > What happens to the RX_CLK when you unplug the cable? It is no longer > receiving anything, so i would expect the RX_CLK to stop ticking. Does that > cause problems for the MAC? > Yes, after the PHY enters hibernation mode that the RX_CLK stop ticking, but for stmmac, it is essential that RX_CLK of PHY is present for software reset completion. Otherwise, the stmmac is failed to complete the software reset and can not init DMA. > Andrew
