Re: [PATCH] PCI: rcar: Demote WARN() to dev_warn_ratelimited() in rcar_pcie_wakeup()

["Krzysztof Wilczyński" <kw@linux.com>]

Hello,

> Avoid large backtrace, it is sufficient to warn the user that there has
> been a link problem. Either the link has failed and the system is in need
> of maintenance, or the link continues to work and user has been informed.
> The message from the warning can be looked up in the sources.
> 
> This makes an actual link issue less verbose.
> 
> First of all, this controller has a limitation in that the controller
> driver has to assist the hardware with transition to L1 link state by
> writing L1IATN to PMCTRL register, the L1 and L0 link state switching
> is not fully automatic on this controller.
> 
> In case of an ASMedia ASM1062 PCIe SATA controller which does not support
> ASPM, on entry to suspend or during platform pm_test, the SATA controller
> enters D3hot state and the link enters L1 state. If the SATA controller
> wakes up before rcar_pcie_wakeup() was called and returns to D0, the link
> returns to L0 before the controller driver even started its transition to
> L1 link state. At this point, the SATA controller did send an PM_ENTER_L1
> DLLP to the PCIe controller and the PCIe controller received it, and the
> PCIe controller did set PMSR PMEL1RX bit.
> 
> Once rcar_pcie_wakeup() is called, if the link is already back in L0 state
> and PMEL1RX bit is set, the controller driver has no way to determine if
> it should perform the link transition to L1 state, or treat the link as if
> it is in L0 state. Currently the driver attempts to perform the transition
> to L1 link state unconditionally, which in this specific case fails with a
> PMSR L1FAEG poll timeout, however the link still works as it is already
> back in L0 state.
> 
> Reduce this warning verbosity. In case the link is really broken, the
> rcar_pcie_config_access() would fail, otherwise it will succeed and any
> system with this controller and ASM1062 can suspend without generating
> a backtrace.

Applied to controller/rcar, thank you!

[1/1] PCI: rcar: Demote WARN() to dev_warn_ratelimited() in rcar_pcie_wakeup()
      https://git.kernel.org/pci/pci/c/a37647d5639b

	Krzysztof