> On 24.10.2019 23:54, Lorenzo Bianconi wrote:
> >> On 24.10.2019 00:23, Lorenzo Bianconi wrote:
> >>> On same device (e.g. U7612E-H1) PCIE_ASPM causes continuous mcu hangs and
> >>> instability and so let's disable PCIE_ASPM by default. This patch has
> >>> been successfully tested on U7612E-H1 mini-pice card
> >>>
> >>> Signed-off-by: Felix Fietkau <nbd@xxxxxxxx>
> >>> Signed-off-by: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
> >>> ---
> >>> drivers/net/wireless/mediatek/mt76/mmio.c | 47 +++++++++++++++++++
> >>> drivers/net/wireless/mediatek/mt76/mt76.h | 1 +
> >>> .../net/wireless/mediatek/mt76/mt76x2/pci.c | 2 +
> >>> 3 files changed, 50 insertions(+)
> >>>
> >
> > [...]
> >
> >>> +
> >>> + if (parent)
> >>> + pcie_capability_clear_word(parent, PCI_EXP_LNKCTL,
> >>> + aspm_conf);
> >>
> >> + linux-pci mailing list
> >
> > Hi Heiner,
> >
> >>
> >> All this seems to be legacy code copied from e1000e.
> >> Fiddling with the low-level PCI(e) registers should be left to the
> >> PCI core. It shouldn't be needed here, a simple call to
> >> pci_disable_link_state() should be sufficient. Note that this function
> >> has a return value meanwhile that you can check instead of reading
> >> back low-level registers.
> >
> > ack, I will add it to v2
> >
> >> If BIOS forbids that OS changes ASPM settings, then this should be
> >> respected (like PCI core does). Instead the network chip may provide
> >> the option to configure whether it activates certain ASPM (sub-)states
> >> or not. We went through a similar exercise with the r8169 driver,
> >> you can check how it's done there.
> >
> > looking at the vendor sdk (at least in the version I currently have) there are
> > no particular ASPM configurations, it just optionally disables it writing directly
> > in pci registers.
> > Moreover there are multiple drivers that are currently using this approach:
> > - ath9k in ath_pci_aspm_init()
> > - tg3 in tg3_chip_reset()
> > - e1000e in __e1000e_disable_aspm()
> > - r8169 in rtl_enable_clock_request()/rtl_disable_clock_request()
> >
> All these drivers include quite some legacy code. I can mainly speak for r8169:
> First versions of the driver are almost as old as Linux. And even though I
> refactored most of the driver still some legacy code for older chip versions
> (like the two functions you mentioned) is included.
>
> > Is disabling the ASPM for the system the only option to make this minipcie
> > work?
> >
>
> No. What we do in r8169:
>
> - call pci_disable_link_state(pdev, PCIE_LINK_STATE_L0S | PCIE_LINK_STATE_L1)
> - If it returns 0, then ASPM (including the L1 sub-states) is disabled.
> - If it returns an errno, then disabling ASPM failed (most likely due to
> BIOS forbidding ASPM changes - pci_disable_link_state will spit out
> a related warning). In this case r8169 configures the chip to not initiate
> transitions to L0s/L1 (the other end of the link may still try to enter
> ASPM states). See rtl_hw_aspm_clkreq_enable(). That's sufficient
> to avoid the ASPM-related problems with certain versions of this chip.
> Maybe your HW provides similar functionality.
yep, I looked at rtl_hw_aspm_clkreq_enable. This is more or less what I did but
unfortunately there is no specific code or documentation I can use for mt76x2e.
So as last chance I decided to disable ASPM directly (in this way the chip is
working fine).
Do you think a kernel parameter to disable ASPM directly would be acceptable?
Regards,
Lorenzo
>
> > Regards,
> > Lorenzo
> >
> Heiner
>
> >>
> >>> +}
> >>> +EXPORT_SYMBOL_GPL(mt76_mmio_disable_aspm);
> >>> +
> >>> void mt76_mmio_init(struct mt76_dev *dev, void __iomem *regs)
> >>> {
> >>> static const struct mt76_bus_ops mt76_mmio_ops = {
> >>> diff --git a/drivers/net/wireless/mediatek/mt76/mt76.h b/drivers/net/wireless/mediatek/mt76/mt76.h
> >>> index 570c159515a0..962812b6247d 100644
> >>> --- a/drivers/net/wireless/mediatek/mt76/mt76.h
> >>> +++ b/drivers/net/wireless/mediatek/mt76/mt76.h
> >>> @@ -578,6 +578,7 @@ bool __mt76_poll_msec(struct mt76_dev *dev, u32 offset, u32 mask, u32 val,
> >>> #define mt76_poll_msec(dev, ...) __mt76_poll_msec(&((dev)->mt76), __VA_ARGS__)
> >>>
> >>> void mt76_mmio_init(struct mt76_dev *dev, void __iomem *regs);
> >>> +void mt76_mmio_disable_aspm(struct pci_dev *pdev);
> >>>
> >>> static inline u16 mt76_chip(struct mt76_dev *dev)
> >>> {
> >>> diff --git a/drivers/net/wireless/mediatek/mt76/mt76x2/pci.c b/drivers/net/wireless/mediatek/mt76/mt76x2/pci.c
> >>> index 73c3104f8858..264bef87e5c7 100644
> >>> --- a/drivers/net/wireless/mediatek/mt76/mt76x2/pci.c
> >>> +++ b/drivers/net/wireless/mediatek/mt76/mt76x2/pci.c
> >>> @@ -81,6 +81,8 @@ mt76pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> >>> /* RG_SSUSB_CDR_BR_PE1D = 0x3 */
> >>> mt76_rmw_field(dev, 0x15c58, 0x3 << 6, 0x3);
> >>>
> >>> + mt76_mmio_disable_aspm(pdev);
> >>> +
> >>> return 0;
> >>>
> >>> error:
> >>>
> >>
>
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