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Date: Tue, 4 Feb 2014 14:51:27 -0800 From: Florian Fainelli <f.fainelli@...il.com> To: Sebastian Hesselbarth <sebastian.hesselbarth@...il.com> Cc: David Miller <davem@...emloft.net>, mugunthanvnm <mugunthanvnm@...com>, netdev <netdev@...r.kernel.org>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Andrew Lunn <andrew@...n.ch> Subject: Re: [PATCH v2 0/5] net: phy: Ethernet PHY powerdown optimization Hi Sebastian, 2014-02-04 Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>: > On 12/17/2013 08:43 PM, David Miller wrote: >> >> From: Sebastian Hesselbarth <sebastian.hesselbarth@...il.com> >> Date: Fri, 13 Dec 2013 10:20:24 +0100 >> >>> This is v2 of the ethernet PHY power optimization patches to reduce >>> power consumption of network PHYs with link that are either unused or >>> the corresponding netdev is down. >>> >>> Compared to the last version, this patch set drops a patch to disable >>> unused PHYs after late initcall, as it is not compatible with a modular >>> mdio bus [1]. I'll investigate different ways to have a modular mdio bus >>> driver get notified when driver loading is done. >>> >>> Again, a branch with v2 applied to v3.13-rc2 can also be found at >>> https://github.com/shesselba/linux-dove.git topic/ethphy-power-v2 >>> >>> [1] http://www.spinics.net/lists/arm-kernel/msg293028.html >> >> >> Series applied, thanks. >> > > David, Mungunthan, Florian, > > as expected the above patches create a Linux to bootloader dependency > that surfaces dumb bootloaders not initializing PHYs correctly. > > Andrew has a Kirkwood based board that does not power-up and restart > auto-negotiation on the powered down PHY after a warm restart. While > this specific bootloader allows a soft-workaround by issuing the > required PHY writes before accessing the interface, others may not. > > I think we should allow the user to soft-disable the automatic > power-down of PHYs, i.e. by exploiting a kernel parameter. > > Do you have any preference for naming it? My call would be something > like libphy.suspend_halted = [0,1] with 1 being the default. The name looks good to me, and it would avoid having to clear the BMCR_PWRDOWN bit during the MDIO bus remove callback to workaround such bootloaders. BTW, it looks like we are omitting a 0.5 seconds delay after clearing the BMCR_PWRDOWN bit: " 22.2.4.1.5 Power Down ... A PHY is not required to meet the RX_CLK and TX_CLK signal functional requirements when either bit 0.11 or bit 0.10 is set to a logic one. A PHY shall meet the RX_CLK and TX_CLK signal functional require- ments defined in 22.2.2 within 0.5 s after both bit 0.11 and 0.10 are cleared to zero." -- Florian -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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