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    SubjectRe: [PATCH] ACPI/NVS: Not save NVS region for new machines to accelerate S3
    On Mon, Jul 21, 2014 at 01:54:56PM +0800, Lan Tianyu wrote:
    > Date: Mon, 21 Jul 2014 13:54:56 +0800
    > From: Lan Tianyu <tianyu.lan@intel.com>
    > To: rjw@rjwysocki.net, lenb@kernel.org, linux-acpi@vger.kernel.org,
    > linux-kernel@vger.kernel.org, gong.chen@linux.intel.com
    > Subject: Re: [PATCH] ACPI/NVS: Not save NVS region for new machines to
    > accelerate S3
    > User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:14.0) Gecko/20120714
    > Thunderbird/14.0
    >
    > On 2014年07月21日 13:01, Chen, Gong wrote:
    > > On Mon, Jul 21, 2014 at 10:14:31AM +0800, Lan Tianyu wrote:
    > >> Date: Mon, 21 Jul 2014 10:14:31 +0800
    > >> From: Lan Tianyu <tianyu.lan@intel.com>
    > >> To: rjw@rjwysocki.net, lenb@kernel.org, linux-acpi@vger.kernel.org,
    > >> linux-kernel@vger.kernel.org, gong.chen@linux.intel.com
    > >> Subject: Re: [PATCH] ACPI/NVS: Not save NVS region for new machines to
    > >> accelerate S3
    > >> User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:14.0) Gecko/20120714
    > >> Thunderbird/14.0
    > >>
    > >> On 2014年07月18日 16:00, Chen, Gong wrote:
    > >>> On Fri, Jul 18, 2014 at 01:55:22PM +0800, Lan Tianyu wrote:
    > >>>> Date: Fri, 18 Jul 2014 13:55:22 +0800
    > >>>> From: Lan Tianyu <tianyu.lan@intel.com>
    > >>>> To: rjw@rjwysocki.net, lenb@kernel.org
    > >>>> Cc: Lan Tianyu <tianyu.lan@intel.com>, linux-acpi@vger.kernel.org,
    > >>>> linux-kernel@vger.kernel.org
    > >>>> Subject: [PATCH] ACPI/NVS: Not save NVS region for new machines to
    > >>>> accelerate S3
    > >>>> X-Mailer: git-send-email 1.7.9.5
    > >>>>
    > >>>> NVS region is saved and restored unconditionally for machines without
    > >>>> nvs_nosave quirk during S3. Tested some new machines and the operation
    > >>>> is not necessary. Saving NVS region also affects S2RAM speed. The time of
    > >>>> NVS saving and restoring depends on the size of NVS region and it consumes
    > >>>> 7~10ms normally.
    > >>>>
    > >>>> This patch is to make machines produced from 2012 to now not saving NVS region
    > >>>> to accelerate S3.
    > >>>>
    > >>> The year 2012 is a mandatory value in the spec?
    > >>>
    > >>
    > >> No, spec indicates that this is only required for S4 and commit 2a6b697
    > >> added this behavior because this can fix S3 bug on some machines. But
    > >> this isn't necessary for all machines and waster time for S3. So this
    > >> patch is to add time base quirk to change default behavior for new machines.
    > >>
    > > If so, I don't think a hard-coded valud in the kernel is a good idea.
    > > Why not providing a quirk via a command line parameter or module parameter.
    > >
    >
    > There is already a kernel command "acpi_sleep=nonvs_s3" to do that. But
    > this needs to be set by user. Otherwise, saving/restoring NVS region
    > also breaks system suspend on some machines and we have added 14
    > nonvs quirks in the acpisleep_dmi_table.
    >
    14 quriks! What a terrible BIOS, isn't it? It's time to cleanup so
    many hacks. I'm not ACPI expert, but such yet another hack is not
    acceptable from my point of view.
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