Messages in this thread | | | Date | Tue, 27 Aug 2019 15:48:06 +0200 | From | Ondřej Jirman <> | Subject | Re: [PATCH] arm64: dts: allwinner: a64: pine64-plus: Add PHY regulator delay |
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Hi,
On Tue, Aug 27, 2019 at 03:34:43PM +0200, Maxime Ripard wrote: > On Sun, Aug 25, 2019 at 03:03:36PM +0200, Jernej Skrabec wrote: > > Depending on kernel and bootloader configuration, it's possible that > > Realtek ethernet PHY isn't powered on properly. It needs some time > > before it can be used. > > > > Fix that by adding 100ms ramp delay to regulator responsible for > > powering PHY. > > > > Fixes: 94dcfdc77fc5 ("arm64: allwinner: pine64-plus: Enable dwmac-sun8i") > > Suggested-by: Ondrej Jirman <megous@megous.com> > > Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net> > > How was that delay found?
I suggested it. There's no delay in the dwmac-sun8i driver, so after enabling the phy power, it will start accessing it over MDIO right away, which is not good.
I suggested the value based on post-reset delay in the PHY's datasheet (30ms). Multiplied ~3x (if I remember correctly) to get some safety margin. Chip has more to do then after the HW reset, and regulator also needs some time to ramp-up.
regards, o.
> It should at least have a comment explaining why it's there. > > Thanks! > Maxime > > -- > Maxime Ripard, Bootlin > Embedded Linux and Kernel engineering > https://bootlin.com
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