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

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Date:	Mon, 18 Jul 2016 10:34:27 +0000
From:	"Zheng, Lv" <lv.zheng@...el.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
CC:	"Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
	"Brown, Len" <len.brown@...el.com>, Lv Zheng <zetalog@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-acpi@...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

Hi, Rafael

> From: Rafael J. Wysocki [mailto:rjw@...ysocki.net]
> Subject: Re: [UPDATE PATCH v2 1/3] ACPICA: Events: Introduce
> acpi_mask_gpe() to implement GPE masking mechanism
> 
> On Monday, July 04, 2016 03:59:07 PM Rafael J. Wysocki wrote:
> > 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].
> 
> I've decided that it's better if this goes in via upstream ACPICA, so it's not
> in the queue any more.
> 
> For the time being, I'd like all changes in the ACPICA code to go in via the
> upstream.

[Lv Zheng] 
OK.
Unlike several others, this is not an urgent feature or a feature that ACPICA upstream doesn't have environment to test.
So we needn't to make in the upstream Linux first.

Thanks and best regards
-Lv