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SubjectRe: [PATCH v2 2/2] mwifiex: pcie: add reset_d3cold quirk for Surface gen4+ devices
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On 7/9/21 8:44 PM, Pali Rohár wrote:

[...]

>> My (very) quick attempt ('echo 1 > /sys/bus/pci/.../reset) at
>> reproducing this didn't work, so I think at very least a network
>> connection needs to be active.
>
> This is doing PCIe function level reset. Maybe you can get more luck
> with PCIe Hot Reset. See following link how to trigger PCIe Hot Reset
> from userspace: https://alexforencich.com/wiki/en/pcie/hot-reset-linux

Thanks for that link! That does indeed do something which breaks the
adapter. Running the script produces

[ 178.388414] mwifiex_pcie 0000:01:00.0: PREP_CMD: card is removed
[ 178.389128] mwifiex_pcie 0000:01:00.0: PREP_CMD: card is removed
[ 178.461365] mwifiex_pcie 0000:01:00.0: performing cancel_work_sync()...
[ 178.461373] mwifiex_pcie 0000:01:00.0: cancel_work_sync() done
[ 178.984106] pci 0000:01:00.0: [11ab:2b38] type 00 class 0x020000
[ 178.984161] pci 0000:01:00.0: reg 0x10: [mem 0x00000000-0x000fffff 64bit pref]
[ 178.984193] pci 0000:01:00.0: reg 0x18: [mem 0x00000000-0x000fffff 64bit pref]
[ 178.984430] pci 0000:01:00.0: supports D1 D2
[ 178.984434] pci 0000:01:00.0: PME# supported from D0 D1 D3hot D3cold
[ 178.984871] pcieport 0000:00:1c.0: ASPM: current common clock configuration is inconsistent, reconfiguring
[ 179.297919] pci 0000:01:00.0: BAR 0: assigned [mem 0xd4400000-0xd44fffff 64bit pref]
[ 179.297961] pci 0000:01:00.0: BAR 2: assigned [mem 0xd4500000-0xd45fffff 64bit pref]
[ 179.298316] mwifiex_pcie 0000:01:00.0: enabling device (0000 -> 0002)
[ 179.298752] mwifiex_pcie: PCI memory map Virt0: 00000000c4593df1 PCI memory map Virt2: 0000000039d67daf
[ 179.300522] mwifiex_pcie 0000:01:00.0: WLAN read winner status failed!
[ 179.300552] mwifiex_pcie 0000:01:00.0: info: _mwifiex_fw_dpc: unregister device
[ 179.300622] mwifiex_pcie 0000:01:00.0: Read register failed
[ 179.300912] mwifiex_pcie 0000:01:00.0: performing cancel_work_sync()...
[ 179.300928] mwifiex_pcie 0000:01:00.0: cancel_work_sync() done

after which the card is unusable (there is no WiFi interface availabel
any more). Reloading the driver module doesn't help and produces

[ 376.906833] mwifiex_pcie: PCI memory map Virt0: 0000000025149d28 PCI memory map Virt2: 00000000c4593df1
[ 376.907278] mwifiex_pcie 0000:01:00.0: WLAN read winner status failed!
[ 376.907281] mwifiex_pcie 0000:01:00.0: info: _mwifiex_fw_dpc: unregister device
[ 376.907293] mwifiex_pcie 0000:01:00.0: Read register failed
[ 376.907404] mwifiex_pcie 0000:01:00.0: performing cancel_work_sync()...
[ 376.907406] mwifiex_pcie 0000:01:00.0: cancel_work_sync() done

again. Performing a function level reset produces

[ 402.489572] mwifiex_pcie 0000:01:00.0: mwifiex_pcie_reset_prepare: adapter structure is not valid
[ 403.514219] mwifiex_pcie 0000:01:00.0: mwifiex_pcie_reset_done: adapter structure is not valid

and doesn't help either.

Running the same command on a kernel with (among other) this patch
unfortunately also breaks the adapter in the same way. As far as I can
tell though, it doesn't run through the reset code added by this patch
(as indicated by the log message when performing FLR), which I assume
in a non-forced scenario, e.g. firmware issues (which IIRC is why this
patch exists), it would?

>> Unfortunately I can't test that with a
>> network connection (and without compiling a custom kernel for which I
>> don't have the time right now) because there's currently another bug
>> deadlocking on device removal if there's an active connection during
>> removal (which also seems to trigger on reset). That one ill be fixed
>> by
>>
>> https://lore.kernel.org/linux-wireless/20210515024227.2159311-1-briannorris@chromium.org/
>>
>> Jonas might know more.

[...]

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