[Unstable] [PATCH] UBUNTU: [Config] CONFIG_SATA_MOBILE_LPM_POLICY=3

[Kai Heng Feng]

> On Mar 29, 2018, at 1:32 AM, Seth Forshee <seth.forshee at canonical.com>  
> wrote:
>
> On Wed, Mar 28, 2018 at 07:21:04PM +0800, Kai-Heng Feng wrote:
>> BugLink: https://bugs.launchpad.net/bugs/1759547
>> Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
>> ---
>>  debian.master/config/config.common.ubuntu | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/debian.master/config/config.common.ubuntu  
>> b/debian.master/config/config.common.ubuntu
>> index e09a65ef0a1f..98a828b82f30 100644
>> --- a/debian.master/config/config.common.ubuntu
>> +++ b/debian.master/config/config.common.ubuntu
>> @@ -7691,7 +7691,7 @@ CONFIG_SATA_DWC=m
>>  CONFIG_SATA_DWC_OLD_DMA=y
>>  CONFIG_SATA_HIGHBANK=y
>>  CONFIG_SATA_INIC162X=m
>> -CONFIG_SATA_MOBILE_LPM_POLICY=0
>> +CONFIG_SATA_MOBILE_LPM_POLICY=3
>
> From the commit message of the patch adding this:
>
>   Also enabling LPM by default is not entirely without risk of
>   regressions. At least min_power is known to cause issues with some
>   disks, including some reports of data corruption.
>
> Is there any risk of these issues with the value you've chosen here?

Yes, users in [1] can't mount rootfs with min_power.

I wrote a patch to quirk their devices to use med_power_with_dipm (i.e.  
CONFIG_SATA_MOBILE_LPM_POLICY=3),
unfortunately their disk still have issues with this setting.

So yes, some disks are buggy under both min_power and med_power_with_dipm.

Since LPM can be set from userspace (e.g. laptop-mode-tools, TLP, powertop),
user will likely to get hit by this bug, one way or another.

In a discussion with Hans [2], he mentioned that Fedora will use  
CONFIG_SATA_MOBILE_LPM_POLICY=3 from v4.15+,
I think we should do the same.

Also, one of our customer does want us to use a saner default for laptops.

[1] https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1726930
[2] https://github.com/linrunner/TLP/issues/84#issuecomment-365929563

Kai-Heng