net: stmmac: fix system hang caused by eee_ctrl_timer during suspend/resume
commit 5f585913 ("net: stmmac: delete the eee_ctrl_timer after napi disabled"), this patch tries to fix system hang caused by eee_ctrl_timer, unfortunately, it only can resolve it for system reboot stress test. System hang also can be reproduced easily during system suspend/resume stess test when mount NFS on i.MX8MP EVK board. In stmmac driver, eee feature is combined to phylink framework. When do system suspend, phylink_stop() would queue delayed work, it invokes stmmac_mac_link_down(), where to deactivate eee_ctrl_timer synchronizly. In above commit, try to fix issue by deactivating eee_ctrl_timer obviously, but it is not enough. Looking into eee_ctrl_timer expire callback stmmac_eee_ctrl_timer(), it could enable hareware eee mode again. What is unexpected is that LPI interrupt (MAC_Interrupt_Enable.LPIEN bit) is always asserted. This interrupt has chance to be issued when LPI state entry/exit from the MAC, and at that time, clock could have been already disabled. The result is that system hang when driver try to touch register from interrupt handler. The reason why above commit can fix system hang issue in stmmac_release() is that, deactivate eee_ctrl_timer not just after napi disabled, further after irq freed. In conclusion, hardware would generate LPI interrupt when clock has been disabled during suspend or resume, since hardware is in eee mode and LPI interrupt enabled. Interrupts from MAC, MTL and DMA level are enabled and never been disabled when system suspend, so postpone clocks management from suspend stage to noirq suspend stage should be more safe. Fixes: 5f585913 ("net: stmmac: delete the eee_ctrl_timer after napi disabled") Signed-off-by:Joakim Zhang <qiangqing.zhang@nxp.com> Signed-off-by: