Date:   Thu, 11 Feb 2021 17:17:20 +0100
From:   Maximilian Luz <luzmaximilian@...il.com>
To:     Hans de Goede <hdegoede@...hat.com>,
        Bastien Nocera <hadess@...ess.net>
Cc:     Mark Gross <mgross@...ux.intel.com>,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] platform/surface: Add platform profile driver



On 2/11/21 4:56 PM, Hans de Goede wrote:
> Hi,
> 
> On 2/8/21 10:38 PM, Maximilian Luz wrote:
>>
>>
>> On 2/8/21 9:27 PM, Hans de Goede wrote:
> 
> <snip>
> 
>>>> +static int convert_ssam_to_profile(struct ssam_device *sdev, enum ssam_tmp_profile p)
>>>> +{
>>>> +    switch (p) {
>>>> +    case SSAM_TMP_PROFILE_NORMAL:
>>>> +        return PLATFORM_PROFILE_QUIET;
>>>> +
>>>> +    case SSAM_TMP_PROFILE_BATTERY_SAVER:
>>>> +        return PLATFORM_PROFILE_LOW_POWER;
>>>> +
>>>> +    case SSAM_TMP_PROFILE_BETTER_PERFORMANCE:
>>>> +        return PLATFORM_PROFILE_BALANCED;
>>>> +
>>>> +    case SSAM_TMP_PROFILE_BEST_PERFORMANCE:
>>>> +        return PLATFORM_PROFILE_PERFORMANCE;
>>>> +
>>>> +    default:
>>>> +        dev_err(&sdev->dev, "invalid performance profile: %d", p);
>>>> +        return -EINVAL;
>>>> +    }
>>>> +}
>>>
>>> I'm not sure about the mapping which you have chosen here. I know that at least for
>>> gnome there are plans to make this stuff available in the UI:
>>>
>>> https://gitlab.gnome.org/Teams/Design/settings-mockups/-/blob/master/power/power.png
>>> http://www.hadess.net/2020/09/power-profiles-daemon-new-project.html
>>
>> Thanks for those links!
>>   
>>> Notice there are only 3 levels in the UI, which will primarily be mapped to:
>>>
>>> PLATFORM_PROFILE_LOW_POWER
>>> PLATFORM_PROFILE_BALANCED
>>> PLATFORM_PROFILE_PERFORMANCE
>>>
>>> (with fallbacks to say QUIET for LOW_POWER of there is no LOW_POWER, but that
>>> mostly is something for userspace to worry about).
>>
>> Interesting, I wasn't aware of that. I was aware of Bastien's work
>> towards implementing user-space support for this but I hadn't yet looked
>> at it in detail (e.g. the "fallback to quiet" is new to me).
> 
> Note that the fallback stuff would not apply here, since you do provide
> all 3 of low-power, balanced and performance. But the current way gnome
> will handle this means that it will be impossible to select "normal" from
> the GNOME ui which feels wrong.
> 
>>> And the power-profile-daemon will likely restore the last used setting on boot,
>>> meaning with your mapping that it will always switch the profile away from
>>> SSAM_TMP_PROFILE_NORMAL, which I assume is the default profile picked at boot ?
>>
>> Pretty much, yeah. AFAICT booting doesn't reset it, but hard-resetting
>> the EC does. Same difference though.
>>   
>>> So ideally we would map PLATFORM_PROFILE_BALANCED (which will be the default
>>> GNOME / power-profile-daemon setting) to SSAM_TMP_PROFILE_NORMAL.
>>>
>>> I know the ABI docs say that drivers should try to use existing values, but
>>> this seems like a good case to add a new value or 2 to the PLATFORM_PROFILE enum.
>>>
>>> During the discussion the following 2 options were given because some devices
>>> may have more then one balanced profile:
>>>
>>> PLATFORM_PROFILE_BALANCED_LOW_POWER:
>>>
>>>                   balanced-low-power:     Balances between low power consumption
>>>                                           and performance with a slight bias
>>>                                           towards low power
>>>
>>> PLATFORM_PROFILE_BALANCED_PERFORMANCE:
>>>
>>>                   balanced-performance:   Balances between performance and low
>>>                                           power consumption with a slight bias
>>>                                           towards performance
>>>
>>> I think it would be better to add 1 or both of these, if we add both
>>> we could e.g. do the following mappings:
>>>
>>> SSAM_TMP_PROFILE_BATTERY_SAVER      ->  PLATFORM_PROFILE_LOW_POWER
>>> SSAM_TMP_PROFILE_NORMAL             ->  PLATFORM_PROFILE_BALANCED_LOW_POWER
>>> SSAM_TMP_PROFILE_BETTER_PERFORMANCE ->  PLATFORM_PROFILE_BALANCED_PERFORMANCE
>>> SSAM_TMP_PROFILE_BEST_PERFORMANCE   ->  PLATFORM_PROFILE_PERFORMANCE
>>>
>>> or we could do:
>>>
>>> SSAM_TMP_PROFILE_BATTERY_SAVER      ->  PLATFORM_PROFILE_LOW_POWER
>>> SSAM_TMP_PROFILE_NORMAL             ->  PLATFORM_PROFILE_BALANCED
>>> SSAM_TMP_PROFILE_BETTER_PERFORMANCE ->  PLATFORM_PROFILE_BALANCED_PERFORMANCE
>>> SSAM_TMP_PROFILE_BEST_PERFORMANCE   ->  PLATFORM_PROFILE_PERFORMANCE
>>>
>>> I'm not sure which is best, I hope you have a better idea of that then me.
>>>
>>> I might even be wrong here and NORMAL might really be more about being QUIET
>>> then it really being BALANCED ? In which case the mapping is fine as is.
>>
>> I can only really speak on the behavior of my Surface Book 2. On that
>> device, the CPU is passively cooled, but the discrete GPU is actively
>> cooled, so I can actually only really talk about active cooling behavior
>> for the dGPU.
>>
>> On that, at least, the normal (Windows calls this 'recommended') profile
>> feels like it targets quiet operation. Using the dGPU with that profile
>> pretty much ensures that the dGPU will be limited in performance by a
>> thermal limiter (around 75°C to 80°C; at least it feels that way), while
>> the fan is somewhat audible but definitely not at maximum speed.
>> Changing the profile to any higher profile (Windows calls those 'better
>> performance' and 'best performance'), the fan becomes significantly more
>> audible. I'm not entirely sure if the performance increase can solely be
>> attributed to cooling though.
>>
>> As far as I've heard, that behavior seems to be similar on other devices
>> with fans for CPU cooling, but I can try to get some more feedback on
>> that.
>>
>> Based on all of this, I thought that this would most resemble a 'quiet'
>> profile. But I'd also be fine with your second suggestion. Calling the
>> last two options 'balanced performance' and 'performance' might be a bit
>> closer to the Windows naming scheme. It doesn't seem like the normal
>> profile does much power limiting in terms of actually capping the power
>> limit of the dGPU, so I think calling this 'balanced' would also make
>> sense to me, especially in light of Gnome's defaults.
> 
> Ack.
> 
> So that means that this is going to need to have a preparation patch
> adding the 2 balanced variants which I mention above. Can you take care
> of that in the next version?

Sure. Already prepared a patch for the 'balanced-performance' one over at [1].
Just needs some squashing and I can send in an updated series. Do you also want
me to add the 'balanced-low-power' version? I'd have chosen 'balanced' and
'balanced-performance' in the new mapping, so there wouldn't be any driver
right now using that.
  
> And since that prep. patch needs to go through Rafael's PM tree anyways,
> maybe also throw in a patch to make ACPI_PLATFORM_PROFILE not user selectable
> and use select on it in the thinkpad_acpi and ideapad_laptop drivers?

There's also already one at [1] for that just waiting to be sent :)

[1]: https://github.com/linux-surface/kernel/commits/s/surface-platform-profile/next

Regards,
Max

> Regards,
> 
> Hans
> 
> 
> 
> 
>>>> +
>>>> +static int convert_profile_to_ssam(struct ssam_device *sdev, enum platform_profile_option p)
>>>> +{
>>>> +    switch (p) {
>>>> +    case PLATFORM_PROFILE_LOW_POWER:
>>>> +        return SSAM_TMP_PROFILE_BATTERY_SAVER;
>>>> +
>>>> +    case PLATFORM_PROFILE_QUIET:
>>>> +        return SSAM_TMP_PROFILE_NORMAL;
>>>> +
>>>> +    case PLATFORM_PROFILE_BALANCED:
>>>> +        return SSAM_TMP_PROFILE_BETTER_PERFORMANCE;
>>>> +
>>>> +    case PLATFORM_PROFILE_PERFORMANCE:
>>>> +        return SSAM_TMP_PROFILE_BEST_PERFORMANCE;
>>>> +
>>>> +    default:
>>>> +        /* This should have already been caught by platform_profile_store(). */
>>>> +        WARN(true, "unsupported platform profile");
>>>> +        return -EOPNOTSUPP;
>>>> +    }
>>>> +}
>>>> +
>>>> +static int ssam_platform_profile_get(struct platform_profile_handler *pprof,
>>>> +                     enum platform_profile_option *profile)
>>>> +{
>>>> +    struct ssam_tmp_profile_device *tpd;
>>>> +    enum ssam_tmp_profile tp;
>>>> +    int status;
>>>> +
>>>> +    tpd = container_of(pprof, struct ssam_tmp_profile_device, handler);
>>>> +
>>>> +    status = ssam_tmp_profile_get(tpd->sdev, &tp);
>>>> +    if (status)
>>>> +        return status;
>>>> +
>>>> +    status = convert_ssam_to_profile(tpd->sdev, tp);
>>>> +    if (status < 0)
>>>> +        return status;
>>>> +
>>>> +    *profile = status;
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static int ssam_platform_profile_set(struct platform_profile_handler *pprof,
>>>> +                     enum platform_profile_option profile)
>>>> +{
>>>> +    struct ssam_tmp_profile_device *tpd;
>>>> +    int tp;
>>>> +
>>>> +    tpd = container_of(pprof, struct ssam_tmp_profile_device, handler);
>>>> +
>>>> +    tp = convert_profile_to_ssam(tpd->sdev, profile);
>>>> +    if (tp < 0)
>>>> +        return tp;
>>>> +
>>>> +    return ssam_tmp_profile_set(tpd->sdev, tp);
>>>> +}
>>>> +
>>>> +static int surface_platform_profile_probe(struct ssam_device *sdev)
>>>> +{
>>>> +    struct ssam_tmp_profile_device *tpd;
>>>> +
>>>> +    tpd = devm_kzalloc(&sdev->dev, sizeof(*tpd), GFP_KERNEL);
>>>> +    if (!tpd)
>>>> +        return -ENOMEM;
>>>> +
>>>> +    tpd->sdev = sdev;
>>>> +
>>>> +    tpd->handler.profile_get = ssam_platform_profile_get;
>>>> +    tpd->handler.profile_set = ssam_platform_profile_set;
>>>> +
>>>> +    set_bit(PLATFORM_PROFILE_LOW_POWER, tpd->handler.choices);
>>>> +    set_bit(PLATFORM_PROFILE_QUIET, tpd->handler.choices);
>>>> +    set_bit(PLATFORM_PROFILE_BALANCED, tpd->handler.choices);
>>>> +    set_bit(PLATFORM_PROFILE_PERFORMANCE, tpd->handler.choices);
>>>> +
>>>> +    platform_profile_register(&tpd->handler);
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static void surface_platform_profile_remove(struct ssam_device *sdev)
>>>> +{
>>>> +    platform_profile_remove();
>>>> +}
>>>> +
>>>> +static const struct ssam_device_id ssam_platform_profile_match[] = {
>>>> +    { SSAM_SDEV(TMP, 0x01, 0x00, 0x01) },
>>>> +    { },
>>>> +};
>>>> +MODULE_DEVICE_TABLE(ssam, ssam_platform_profile_match);
>>>> +
>>>> +static struct ssam_device_driver surface_platform_profile = {
>>>> +    .probe = surface_platform_profile_probe,
>>>> +    .remove = surface_platform_profile_remove,
>>>> +    .match_table = ssam_platform_profile_match,
>>>> +    .driver = {
>>>> +        .name = "surface_platform_profile",
>>>> +        .probe_type = PROBE_PREFER_ASYNCHRONOUS,
>>>> +    },
>>>> +};
>>>> +module_ssam_device_driver(surface_platform_profile);
>>>> +
>>>> +MODULE_AUTHOR("Maximilian Luz <luzmaximilian@...il.com>");
>>>> +MODULE_DESCRIPTION("Platform Profile Support for Surface System Aggregator Module");
>>>> +MODULE_LICENSE("GPL");
>>>>
>>>
>>
> 

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