Hi Sergio,
On 12/3/20 4:58 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.
Excellent! I am glad to see an effort to get these problems resolved.
I still have to switch back to much earlier version of this PCI
driving code to get reliable working behavior.
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.
What kernel did you generate these patches against?
They didn't apply completely cleanly for me against 5.5 or 5.6.0-rc5.
Minor reject and some fuzzing, easy enough to fix for testing.
Running 5.6.0-rc5 I get the following failure on my hardware during boot:
...
rt2880-pinmux pinctrl: pcie is already enabled
mt7621-pci 1e140000.pcie: Error applying setting, reverse things back
mt7621-pci 1e140000.pcie: Unable to request GPIO reset in slot 1
mt7621-pci 1e140000.pcie: Parsing DT failed
mt7621-pci: probe of 1e140000.pcie failed with error -16
FWIW: running the original 5.6.0-rc5 code gives a few different
PCI startup failures - but PCI devices never work properly. I can
send the error trace output if useful, but it is similar to what
I have posted in the past.
Regards
Greg
Changes in v2:
* restore configuration for pers mode to GPIO.
* Avoid to read FTS_NUM register in reset state.
Best regards,
Sergio Paracuellos
Sergio Paracuellos (5):
staging: mt7621-pci: use gpios for properly reset
staging: mt7621-pci: change value for 'PERST_DELAY_US'
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
drivers/staging/mt7621-dts/mt7621.dtsi | 11 ++-
.../mt7621-pci/mediatek,mt7621-pci.txt | 7 +-
drivers/staging/mt7621-pci/pci-mt7621.c | 94 ++++++++++++-------
3 files changed, 72 insertions(+), 40 deletions(-)
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