Messages in this thread | | | Date | Sat, 02 Nov 2019 02:18:27 +0100 | From | Michael Walle <> | Subject | Re: [RFC PATCH 3/3] net: phy: at803x: add device tree binding |
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Am 2019-10-31 18:35, schrieb Florian Fainelli: > On 10/31/19 10:22 AM, Michael Walle wrote: >> Am 2019-10-31 00:59, schrieb Michael Walle: >>>>> + >>>>> + if (of_property_read_bool(node, "atheros,keep-pll-enabled")) >>>>> + priv->flags |= AT803X_KEEP_PLL_ENABLED; >>>> >>>> This should probably be a PHY tunable rather than a Device Tree >>>> property >>>> as this delves more into the policy than the pure hardware >>>> description. >>> >>> To be frank. I'll first need to look into PHY tunables before >>> answering ;) >>> But keep in mind that this clock output might be used anywhere on the >>> board. It must not have something to do with networking. The PHY has >>> a >>> crystal and it can generate these couple of frequencies regardless of >>> its network operation. >> >> Although it could be used to provide any clock on the board, I don't >> know >> if that is possible at the moment, because the PHY is configured in >> config_init() which is only called when someone brings the interface >> up, >> correct? >> >> Anyway, I don't know if that is worth the hassle because in almost all >> cases the use case is to provide a fixed clock to the MAC for an RGMII >> interface. I don't know if that really fits a PHY tunable, because in >> the worst case the link won't work at all if the SoC expects an >> always-on clock. > > Well, that was my question really, is the clock output being controlled > the actual RXC that will feed back to the MAC or is this is another > clock output pin (sorry if you indicated that before and I missed it)?
No it is not the RX clock. The PHY has three clock pins, RX clock, TX clock and a general purpose CLK_25M pin.
> If this is the PHY's RXC, then does the configuration (DSP, PLL, XTAL) > matter at all on the generated output frequency, or is this just a > choice for the board designer, and whether the PHY is configured for > MII/RGMII, it outputs the appropriate clock at 25/125Mhz?
The RXC changes the frequency according to the speed.
-- -michael
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