linux-kernel - Re: [UPDATE PATCH v2 1/3] ACPICA: Events: Introduce acpi_mask

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Date:	Mon, 04 Jul 2016 15:59:07 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Lv Zheng <lv.zheng@...el.com>
Cc:	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Len Brown <len.brown@...el.com>, Lv Zheng <zetalog@...il.com>,
	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org
Subject: Re: [UPDATE PATCH v2 1/3] ACPICA: Events: Introduce acpi_mask_gpe() to implement GPE masking mechanism

On Thursday, June 23, 2016 03:05:47 PM Lv Zheng wrote:
> (remove acpi_unmask_gpe() from the patch description)
> 
> There is a facility in Linux, developers can control the enabling/disabling
> of a GPE via /sys/firmware/acpi/interrupts/gpexx. This is mainly for
> debugging purposes.
> 
> But many users expect to use this facility to implement quirks to mask a
> specific GPE when there is a gap in Linux causing this GPE to flood. This
> is not working correctly because currently this facility invokes
> enabling/disabling counting based GPE driver APIs:
>  acpi_enable_gpe()/acpi_disable_gpe()
> and the GPE drivers can still affect the count to mess up the GPE
> masking purposes.
> 
> However, most of the IRQ chip designs allow masking/unmasking IRQs via a
> masking bit which is different from the enabled bit to achieve the same
> purpose. But the GPE hardware doesn't contain such a feature, this brings
> the trouble.
> 
> In this patch, we introduce a software mechanism to implement the GPE
> masking feature, and acpi_mask_gpe() are provided to the OSPMs to
> mask/unmask GPEs in the above mentioned situation instead of
> acpi_enable_gpe()/acpi_disable_gpe(). ACPICA BZ 1102. Lv Zheng.
> 
> Link: https://bugs.acpica.org/show_bug.cgi?id=1102
> Signed-off-by: Lv Zheng <lv.zheng@...el.com>

I've queued up this one and the [2/3] and please see my comments on the [3/3].

Thanks,
Rafael