Re: [PATCH v4 0/6] staging: mt7621-pci: re-do reset boot process

[Greg Ungerer <gerg@kernel.org>]

Hi Sergio,

On 14/3/20 6:09 am, Sergio Paracuellos wrote:
> Some time ago Greg Ungerer reported some random hangs using
> the staging mt7621-pci driver:
> 
> See:
> * http://driverdev.linuxdriverproject.org/pipermail/driverdev-devel/2019-June/134947.html
> 
> Try to fix that is the main motivation of this patch series.
> 
> Also in openwrt there is a driver for mt7621-pci which seems was rewritten
> from scratch (for kernel 4.14) by Ryder Lee and Weijie Gao from mediatek.
> There the approach for reset assert-deassert process is to set as 'gpio'
> the function for all the 'pcie' group for the pinctrl driver and use those
> gpio's as a reset for the end points. The driver I am talking about is still
> using legacy pci and legacy gpio kernel interfaces. IMHO, the correct thing
> to do is make this staging driver properly clean and functional and put it
> in its correct place in the mainline.
> 
> See:
> * https://gist.github.com/dengqf6/7a9e9b4032d99f1a91dd9256c8a65c36
> 
> Because of all of this this patch series tries to avoid random hangs of boot
> trying to use the 'reset-gpios' approach.
> 
> Changes are being tested by openwrt people and seems to work.
> 
> Hope this helps.
> 
> Changes in v4:
> * Make use of 'devm_gpiod_get_index_optional' instead of 'devm_gpiod_get_index'.
> * Use 'dev_err' instead of 'dev_notice' and return ERR_PTR if
> 'devm_gpiod_get_index_optional' fails.
> * Rename pers dealy macro to PERST_DELAY_MS.
> * Add new patch 6 which removes function 'mt7621_reset_port' not needed anymore.

Testing this v4 series always fails during boot with:

...
NET: Registered protocol family 17
NET: Registered protocol family 15
8021q: 802.1Q VLAN Support v1.8
Loading compiled-in X.509 certificates
AppArmor: AppArmor sha1 policy hashing enabled

rt2880-pinmux pinctrl: pcie is already enabled
mt7621-pci 1e140000.pcie: Error applying setting, reverse things back
mt7621-pci 1e140000.pcie: Failed to get GPIO for PCIe1
mt7621-pci 1e140000.pcie: Parsing DT failed
mt7621-pci: probe of 1e140000.pcie failed with error -16

UBI error: cannot open mtd 3, error -19
hctosys: unable to open rtc device (rtc0)
cfg80211: Loading compiled-in X.509 certificates for regulatory database
cfg80211: Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7'
...

It never hangs, always boots up all the way. But always the same failure
with PCIe.

Regards
Greg



> Changes in v3:
> * Avoid to fail if gpio descriptor fails on get.
> * re-do PATCH 1 commit message.
> * Take into account gpio low polarity on request and assert and deassert.
> * Review error path of driver to properly release gpio's resources.
> 
> Changes in v2:
> * restore configuration for pers mode to GPIO.
> * Avoid to read FTS_NUM register in reset state.
> * Release gpio's patch added
> 
> Best regards,
>      Sergio Paracuellos
> 
> 
> Sergio Paracuellos (6):
>    staging: mt7621-pci: use gpios for properly reset
>    staging: mt7621-pci: change value for 'PERST_DELAY_MS'
>    staging: mt7621-dts: make use of 'reset-gpios' property for pci
>    staging: mt7621-pci: bindings: update doc accordly to last changes
>    staging: mt7621-pci: release gpios after pci initialization
>    staging: mt7621-pci: delete no more needed 'mt7621_reset_port'
> 
>   drivers/staging/mt7621-dts/mt7621.dtsi        |  11 +-
>   .../mt7621-pci/mediatek,mt7621-pci.txt        |   7 +-
>   drivers/staging/mt7621-pci/pci-mt7621.c       | 122 ++++++++++--------
>   3 files changed, 82 insertions(+), 58 deletions(-)
> 
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