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Subject: Re: [PATCH] platform/surface: Add platform profile driver
To:     Maximilian Luz <luzmaximilian@gmail.com>,
        Bastien Nocera <hadess@hadess.net>
Cc:     Mark Gross <mgross@linux.intel.com>,
        platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20210208194903.3039142-1-luzmaximilian@gmail.com>
 <cc9d27aa-955d-1cd1-19b8-9b18bdc6b8a2@redhat.com>
 <c485a731-4378-239f-95e7-3b588f13cb66@gmail.com>
 <dfc90822-d13e-cfc9-af99-0f7b78d2a286@redhat.com>
 <caa365e1-b371-fdcb-f947-2cdb34d5bcf8@gmail.com>
From:   Hans de Goede <hdegoede@redhat.com>
Message-ID: <966e2e3d-d3df-747c-069a-71c5552d1594@redhat.com>
Date:   Thu, 11 Feb 2021 17:31:25 +0100
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Hi,

On 2/11/21 5:17 PM, Maximilian Luz wrote:
> 
> 
> 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.

I see at [1] that for now you've just added 'balanced-performance' that is probably
best, since as you say atm there are no users for 'balanced-low-power' .

>> 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 :)

Nice, thank you!

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

The platform-profile bits which you have here all look good to me.

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@gmail.com>");
>>>>> +MODULE_DESCRIPTION("Platform Profile Support for Surface System Aggregator Module");
>>>>> +MODULE_LICENSE("GPL");
>>>>>
>>>>
>>>
>>
>