[PATCH v3 1/2] net: stmmac: provide flag to disable EEE

[Russell King (Oracle)]

On Mon, Mar 23, 2026 at 11:39:32AM +0200, Laurent Pinchart wrote:
> From: "Russell King (Oracle)" <rmk+kernel at armlinux.org.uk>
> 
> Some platforms have problems when EEE is enabled, and thus need a way
> to disable stmmac EEE support. Add a flag before the other LPI related
> flags which tells stmmac to avoid populating the phylink LPI
> capabilities, which causes phylink to call phy_disable_eee() for any
> PHY that is attached to the affected phylink instance.
> 
> iMX8MP is an example - the lpi_intr_o signal is wired to an OR gate
> along with the main dwmac interrupts. Since lpi_intr_o is synchronous
> to the receive clock domain, and takes four clock cycles to clear, this
> leads to interrupt storms as the interrupt remains asserted for some
> time after the LPI control and status register is read.
> 
> This problem becomes worse when the receive clock from the PHY stops
> when the receive path enters LPI state - which means that lpi_intr_o
> can not deassert until the clock restarts. Since the LPI state of the
> receive path depends on the link partner, this is out of our control.
> We could disable RX clock stop at the PHY, but that doesn't get around
> the slow-to-deassert lpi_intr_o mentioned in the above paragraph.
> 
> Previously, iMX8MP worked around this by disabling gigabit EEE, but
> this is insufficient - the problem is also visible at 100M speeds,
> where the receive clock is slower.
> 
> There is extensive discussion and investigation in the thread linked
> below, the result of which is summarised in this commit message.
> 
> Reported-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> Closes: https://lore.kernel.org/r/20251026122905.29028-1-laurent.pinchart@ideasonboard.com
> Signed-off-by: Russell King (Oracle) <rmk+kernel at armlinux.org.uk>

As you are sending this on my behalf, you need to add your s-o-b after
mine:

 Any further SoBs (Signed-off-by:'s) following the author's SoB are from
 people handling and transporting the patch, but were not involved in its
 development. SoB chains should reflect the **real** route a patch took
 as it was propagated to the maintainers and ultimately to Linus, with
 the first SoB entry signalling primary authorship of a single author.

Thanks.

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