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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@ideasonboard.com> Closes: https://lore.kernel.org/r/20251026122905.29028-1-laurent.pinchart@ideasonboard.com Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> Tested-by: Ovidiu Panait <ovidiu.panait.rb@renesas.com> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com> Link: https://patch.msgid.link/20260325210003.2752013-2-laurent.pinchart@ideasonboard.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
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