Re: [PATCH] gpiolib: acpi: Add gpiolib_acpi_run_edge_events_on_boot option and blacklist

[Hans de Goede]

Hi Andy,

On 26-08-19 11:11, Andy Shevchenko wrote:
> On Fri, Aug 23, 2019 at 11:52:55PM +0200, Hans de Goede wrote:
> > Another day; another DSDT bug we need to workaround...
> >
> > Since commit ca876c7483b6 ("gpiolib-acpi: make sure we trigger edge events
> > at least once on boot") we call _AEI edge handlers at boot.
> >
> > In some rare cases this causes problems. One example of this is the Minix
> > Neo Z83-4 mini PC, this device has a clear DSDT bug where it has some copy
> > and pasted code for dealing with Micro USB-B connector host/device role
> > switching, while the mini PC does not even have a micro-USB connector.
> > This code, which should not be there, messes with the DDC data pin from
> > the HDMI connector (switching it to GPIO mode) breaking HDMI support.
> >
> > To avoid problems like this, this commit adds a new
> > gpiolib_acpi_run_edge_events_on_boot kernel commandline option which
> > can be "on", "off", or "auto" (default).
> >
> > In auto mode the default is on and a DMI based blacklist is used,
> > the initial version of this blacklist contains the Minix Neo Z83-4
> > fixing the HDMI being broken on this device.
>
> > +static int gpiolib_acpi_run_edge_events_on_boot = -1;
> > +
> > +static int __init gpiolib_acpi_run_edge_events_on_boot_setup(char *arg)
> > +{
>
> > +	if (!strcmp(arg, "on"))
> > +		gpiolib_acpi_run_edge_events_on_boot = 1;
> > +	else if (!strcmp(arg, "off"))
> > +		gpiolib_acpi_run_edge_events_on_boot = 0;
>
> kstrtobool() ?
>
> > +	else if (!strcmp(arg, "auto"))
> > +		gpiolib_acpi_run_edge_events_on_boot = -1;
> > +
> > +	return 1;
> > +}
>
> > +
> > +__setup("gpiolib_acpi_run_edge_events_on_boot=",
> > +        gpiolib_acpi_run_edge_events_on_boot_setup);
>
> Can't we use module_param() ?
> The resulting option would be 'gpiolib_acpi.foo=...'

I was expecting that would not work, since gpiolib is a bool
not a tristate, but it seems that if there is no module-name
to use as prefix for module-parameters the kernel simply uses
the .c file name, so this works and yes, this is better then
using __setup, will fix for v2.

> > +{
>
> > +	if (gpiolib_acpi_run_edge_events_on_boot == -1) {
> > +		if (dmi_check_system(run_edge_events_on_boot_blacklist))
> > +			gpiolib_acpi_run_edge_events_on_boot = 0;
> > +		else
> > +			gpiolib_acpi_run_edge_events_on_boot = 1;
> > +	}
>
> Can we run this at an initcall once and use variable instead of calling a
> method below?

I was a bit worried about init ordering, but I've checked and dmi_setup()
is done as a core_initcall, so we can do this once as a postcore_initcall
which should be early enough, will fix for v2.

> > +	return gpiolib_acpi_run_edge_events_on_boot;
> > +}
> > +
> >   static void acpi_gpiochip_request_irq(struct acpi_gpio_chip *acpi_gpio,
> >   				      struct acpi_gpio_event *event)
> >   {
> > @@ -170,10 +211,13 @@ static void acpi_gpiochip_request_irq(struct acpi_gpio_chip *acpi_gpio,
> >   	event->irq_requested = true;
> >   
> >   	/* Make sure we trigger the initial state of edge-triggered IRQs */
> > -	value = gpiod_get_raw_value_cansleep(event->desc);
> > -	if (((event->irqflags & IRQF_TRIGGER_RISING) && value == 1) ||
> > -	    ((event->irqflags & IRQF_TRIGGER_FALLING) && value == 0))
> > -		event->handler(event->irq, event);
> > +	if (acpi_gpiochip_run_edge_events_on_boot() &&
> > +	    (event->irqflags & (IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING))) {
> > +		value = gpiod_get_raw_value_cansleep(event->desc);
> > +		if (((event->irqflags & IRQF_TRIGGER_RISING) && value == 1) ||
> > +		    ((event->irqflags & IRQF_TRIGGER_FALLING) && value == 0))
> > +			event->handler(event->irq, event);
> > +	}

Regards,

Hans