linux-kernel - Re: [PATCH 4.19 16/50] gpiolib: acpi: Add gpiolib_acpi_run_edge_events_on

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Message-ID: <20190919074601.GA6968@amd>
Date:   Thu, 19 Sep 2019 09:46:01 +0200
From:   Pavel Machek <pavel@...x.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Daniel Drake <drake@...lessm.com>,
        Ian W MORRISON <ianwmorrison@...il.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH 4.19 16/50] gpiolib: acpi: Add
 gpiolib_acpi_run_edge_events_on_boot option and blacklist

On Wed 2019-09-18 08:18:59, Greg Kroah-Hartman wrote:
> From: Hans de Goede <hdegoede@...hat.com>
> 
> commit 61f7f7c8f978b1c0d80e43c83b7d110ca0496eb4 upstream.
> 
> 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
> allows disabling the running of _AEI edge event handlers at boot.

So... apparently Windows does _not_ run _AEI edge event handlers at
boot, otherwise Minix would realize that fault.

Would it make sense not to do it by default, either?

Best regards,
								Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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