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

From: Sergio Paracuellos <sergio.paracuellos@gmail.com>
To: gregkh@linuxfoundation.org
Cc: ryder.lee@mediatek.com, driverdev-devel@linuxdriverproject.org,
	weijie.gao@mediatek.com, gerg@kernel.org, neil@brown.name
Subject: [PATCH v4 0/6]  staging: mt7621-pci: re-do reset boot process
Date: Fri, 13 Mar 2020 21:09:07 +0100	[thread overview]
Message-ID: <20200313200913.24321-1-sergio.paracuellos@gmail.com> (raw)

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.

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(-)

-- 
2.25.1

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