On Wed, May 27, 2020 at 12:38 PM Hans Verkuil <hverkuil@xxxxxxxxx> wrote:
> However, I discovered that patch 256efaea1fdc ("gpiolib: fix up emulated
> open drain outputs") broke the cec-gpio driver on the Raspberry Pi starting
> with kernel v5.5.
>
> The CEC pin is an open drain pin that is used in both input and output
> directions and has an interrupt (which is of course disabled while in
> output mode).
>
> With this patch the interrupt can no longer be requested:
>
> [ 4.157806] gpio gpiochip0: (pinctrl-bcm2835): gpiochip_lock_as_irq: tried to flag a GPIO set as output for IRQ
>
> [ 4.168086] gpio gpiochip0: (pinctrl-bcm2835): unable to lock HW IRQ 7 for IRQ
> [ 4.175425] genirq: Failed to request resources for cec-gpio@7 (irq 79) on irqchip pinctrl-bcm2835
> [ 4.184597] cec-gpio: probe of cec-gpio@7 failed with error -5
There is nothing conceptually wrong with that patch so I think we
need to have the irqchip code check if it is input *OR* open drain.
I'll send a separate patch for this, it should be an easy fix.
Yours,
Linus Walleij
