On Friday, July 23, 2021, Andrew Jeffery [off-list ref] wrote:

Hello,

This series does a bunch of crimes, so it's an RFC. I'm cross-posting to
the
pinctrl/GPIO and LEDs lists because the PCA955x devices impact all of
them. What
needs fixing is the leds-pca955x driver's failure to map the GPIO
numberspace to
the pin numberspace of the PCA955x devices. The series solves that by
implementing pinctrl and pinmux in the leds-pca955x driver.

Things I'm unsure about:

1. Patch 1: The pinctrl_gpio_as_pin() API feels a bit dirty, not sure what
   others thoughts are on that (Linus?).

2. Patch 2: I've added a new callback to hook the entirety of the pinctrl
map
   parsing rather than supplying a subnode-specific callback. This was
necessary
   to handle the PCA955x devicetree binding in a backwards compatible way.

3. Patch 4: The PCA955x devices don't actually have any pinmux hardware,
but the
   properties of the pinctrl/pinmux subsystems in the kernel map nicely
onto the
   problem we have. But it's quite a bit of code...

4. Patch 6: I also lost a bunch of time to overlooking the get_group_pins()
   callback for pinctrl, and it seems odd to me that it isn't required.

Please review!

Sounds like a hack. I was briefly looking into patches 1-4 and suddenly
realized that the fix can be similar as in PCA9685 (PWM), I.e. we always
have chips for the entire pin space and one may map them accordingly,
requested in one realm (LED) in the other (GPIO) automatically is BUSY. Or
I missed the point?

Andrew

Andrew Jeffery (6):
  pinctrl: Add pinctrl_gpio_as_pin()
  pinctrl: Add hook for device-specific map parsing
  leds: pca955x: Relocate chipdef-related descriptors
  leds: pca955x: Use pinctrl to map GPIOs to pins
  ARM: dts: rainier: Add presence-detect and fault indictor GPIO
    expander
  pinctrl: Check get_group_pins callback on init

 arch/arm/boot/dts/aspeed-bmc-ibm-rainier.dts |  76 +++
 drivers/leds/leds-pca955x.c                  | 554 +++++++++++++++----
 drivers/pinctrl/core.c                       |  28 +-
 include/linux/pinctrl/pinctrl.h              |   4 +
 4 files changed, 566 insertions(+), 96 deletions(-)

--
2.30.2

-- 
With Best Regards,
Andy Shevchenko
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