linux-kernel - Re: [PATCH] mfd: Fix RTS5227 (and others) powermanagement

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Date:   Wed, 6 Dec 2017 16:44:03 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Lee Jones <lee.jones@...aro.org>
Cc:     linux-kernel@...r.kernel.org, Rui Feng <rui_feng@...lsil.com.cn>
Subject: Re: [PATCH] mfd: Fix RTS5227 (and others) powermanagement

Hi,

On 06-12-17 16:42, Lee Jones wrote:
> On Wed, 06 Dec 2017, Hans de Goede wrote:
> 
>> Hi,
>>
>> On 06-12-17 12:21, Hans de Goede wrote:
>>> Commit 8275b77a1513 ("mfd: rts5249: Add support for RTS5250S power
>>> saving") adds powersaving support for device-ids 5249 524a and 525a.
>>>
>>> But as a side effect it breaks ASPM support for all the other device-ids,
>>> causing e.g. the Haswell CPU on a Lenovo T440s to not go into a higher
>>> c-state then PC3, while previously it would go to PC7, causing the
>>> machine to idle at 7.4W instead of 6.6W!
>>>
>>> The problem here is the new option.dev_aspm_mode field, which only gets
>>> explicitly initialized in the new code for the device-ids 5249 524a and
>>> 525a. Leaving the dev_aspm_mode 0 for the other device-ids.
>>>
>>> The default dev_aspm_mode 0 is mapped to DEV_ASPM_DISABLE, but the
>>> old behavior of calling rtsx_pci_enable_aspm() when idle and
>>> rtsx_pci_disable_aspm() when busy happens when dev_aspm_mode ==
>>> DEV_ASPM_DYNAMIC.
>>>
>>> This commit changes the enum so that 0 = DEV_ASPM_DYNAMIC matching the
>>> old default behavior, fixing the pm regression with the other device-ids.
>>>
>>> Cc: Rui Feng <rui_feng@...lsil.com.cn>
>>> Signed-off-by: Hans de Goede <hdegoede@...hat.com>
>>
>> p.s.
>>
>> 2 remarks:
>>
>> 1. As this is a regression in 4.15, please queue this up as a fix for 4.15
>>     (I prioritized bisecting this, which took me a whole day to get a fix
>>      ready in time for 4.15).
> 
> If this is aimed at -the rcs, you should apply a Fixes: tag.

Right, I should have thought of that myself.

> Happy to do it for you this time.

Thanks you.

Regards,

Hans