Hi, > From: Guenter Roeck [mailto:li...@roeck-us.net] > Sent: Tuesday, April 18, 2017 3:45 AM > Subject: Re: [PATCH] ACPICA: Export mutex functions > > On Mon, Apr 17, 2017 at 07:27:37PM +0000, Moore, Robert wrote: > > > > > -----Original Message----- > > > From: Moore, Robert > > > Sent: Monday, April 17, 2017 10:13 AM > > > To: Guenter Roeck <li...@roeck-us.net>; Zheng, Lv <lv.zh...@intel.com> > > > Cc: Wysocki, Rafael J <rafael.j.wyso...@intel.com>; Len Brown > > > <l...@kernel.org>; linux-a...@vger.kernel.org; de...@acpica.org; linux- > > > ker...@vger.kernel.org > > > Subject: RE: [PATCH] ACPICA: Export mutex functions > > > > > > There is a model for the drivers to directly acquire an AML mutex > > > object. That is why the acquire/release public interfaces were added to > > > ACPICA. > > > > > > I forget all of the details, but the model was developed with MS and > > > others during the ACPI 6.0 timeframe. > > > > > > > > [Moore, Robert] > > > > > > Here is the case where the OS may need to directly acquire an AML mutex: > > > > From the ACPI spec: > > > > 19.6.2 Acquire (Acquire a Mutex) > > > > Note: For Mutex objects referenced by a _DLM object, the host OS may also > > contend for ownership. > > > From the context in the dsdt, and from description of expected use cases for > _DLM objects I can find, this is what the mutex is used for (to serialize > access to a resource on a low pin count serial interconnect, aka LPC). > > What does that mean in practice ? That I am not supposed to use it because > it doesn't follow standard ACPI mutex declaration rules ? >
Could you find related _DLMs in your DSDT? If there is any, could you please post it here for reference? Thanks Lv > Thanks, > Guenter > > > > > > > > > Other than this case, the OS/drivers should never need to directly acquire > > an AML mutex. > > Bob > >
