From: Mike Looijmans <mike.looijmans@topic.nl>
To: Jonathan Cameron <jic23@kernel.org>,
Linus Walleij <linus.walleij@linaro.org>
Cc: linux-iio <linux-iio@vger.kernel.org>,
"Dan Robertson" <dan@dlrobertson.com>,
"Gaëtan André" <rvlander@gaetanandre.eu>,
"Jonathan Bakker" <xc-racer2@live.ca>,
"Lars-Peter Clausen" <lars@metafoo.de>,
"Peter Meerwald-Stadler" <pmeerw@pmeerw.net>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v6 2/2] iio: accel: Add support for the Bosch-Sensortec BMI088
Date: Mon, 25 Jan 2021 08:59:43 +0100 [thread overview]
Message-ID: <5fcf1954-f257-79d2-970b-de188fca4613@topic.nl> (raw)
In-Reply-To: <20210124132344.7181bd06@archlinux>
See below
Met vriendelijke groet / kind regards,
Mike Looijmans
System Expert
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On 24-01-2021 14:23, Jonathan Cameron wrote:
> On Sun, 24 Jan 2021 00:21:13 +0100
> Linus Walleij <linus.walleij@linaro.org> wrote:
>
>> On Sat, Jan 23, 2021 at 4:35 PM Jonathan Cameron <jic23@kernel.org> wrote:
>>> [Me]
>>>> Next, I think it is better to let suspend/resume, i.e. system PM
>>>> reuse runtime PM since you're implementing that. This is why
>>>> we invented PM runtime force resume and force suspend.
>>> Here the driver is turning more off for full suspend than in the
>>> runtime path. If that results in significant extra delay then
>>> it's not appropriate to have that in the runtime suspend path.
>> I see the point.
>>
>> The resume path calls bmi088_accel_enable() which incurs
>> a 5ms delay.
>>
>> The runtime resume path incurs a 1 ms delay.
>>
>> The runtime autosuspend kicks in after 2 ms.
It's set to 2 seconds as I understand it. This to support reading a
single value every second or so.
>>
>>> Maybe the simplification of not doing the deeper power saving
>>> mode is worth the extra power cost or extra delay, but
>>> I'm not yet convinced.
>> I would personally set the autosuspend to ~20ms and just use
>> one path and take a hit of 5 ms whenever we go down between
>> measures if it is a system that is for human interaction, but for
>> control systems this more complex set-up may be better for
>> response latencies.
>>
>> The current approach may be better tuned to perfection and
>> we are all perfectionists :D
>>
>> I'm just worrying a little about bugs and maintainability.
> Fully understood. Though for things like this I like to leave
> it at the discretion of the driver author as fairly safe they
> are a user of the device.
>
> May well make sense to go with the longer times as you
> suggest though! Over to you Mike :)
I've been digging in the datasheet and it's really unclear how you're
supposed to control the two power registers.
I think it's best to just put both control values into on/off state at
the same time. I also prefer the simplicity of Linus' suggestion. I'll
do some testing to see if the device behaves properly.
--
Mike Looijmans
next prev parent reply other threads:[~2021-01-25 8:06 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-19 12:46 [PATCH v6 1/2] dt-bindings: iio: accel: Add bmi088 accelerometer bindings Mike Looijmans
2021-01-19 12:46 ` [PATCH v6 2/2] iio: accel: Add support for the Bosch-Sensortec BMI088 Mike Looijmans
2021-01-20 10:09 ` kernel test robot
2021-01-20 20:22 ` Jonathan Cameron
[not found] ` <1b153bce-a66a-45ee-a5c6-963ea6fb1c82.949ef384-8293-46b8-903f-40a477c056ae.c4ec3c42-7acb-4ce8-997f-adf405d31335@emailsignatures365.codetwo.com>
[not found] ` <1b153bce-a66a-45ee-a5c6-963ea6fb1c82.0d2bd5fa-15cc-4b27-b94e-83614f9e5b38.ca49b241-105e-4dde-a295-e8168cb6d390@emailsignatures365.codetwo.com>
2021-01-21 9:02 ` Mike Looijmans
2021-01-22 22:38 ` Linus Walleij
2021-01-23 15:35 ` Jonathan Cameron
2021-01-23 23:21 ` Linus Walleij
2021-01-24 13:23 ` Jonathan Cameron
[not found] ` <1b153bce-a66a-45ee-a5c6-963ea6fb1c82.949ef384-8293-46b8-903f-40a477c056ae.e23f1b65-3084-4bd7-abd5-c186f8c4c35c@emailsignatures365.codetwo.com>
[not found] ` <1b153bce-a66a-45ee-a5c6-963ea6fb1c82.0d2bd5fa-15cc-4b27-b94e-83614f9e5b38.4d211e5c-af1f-4f0a-9714-ec208ef9be8d@emailsignatures365.codetwo.com>
2021-01-25 7:59 ` Mike Looijmans [this message]
2021-01-19 23:28 ` [PATCH v6 1/2] dt-bindings: iio: accel: Add bmi088 accelerometer bindings Rob Herring
2021-01-20 1:31 ` Rob Herring
[not found] ` <1b153bce-a66a-45ee-a5c6-963ea6fb1c82.949ef384-8293-46b8-903f-40a477c056ae.06120990-9bfb-4196-a6ce-19c5b16aae9a@emailsignatures365.codetwo.com>
[not found] ` <1b153bce-a66a-45ee-a5c6-963ea6fb1c82.0d2bd5fa-15cc-4b27-b94e-83614f9e5b38.70d7c9ca-f015-4fc4-8136-1c0364cd5511@emailsignatures365.codetwo.com>
2021-01-20 7:21 ` Mike Looijmans
2021-01-20 18:50 ` Jonathan Cameron
[not found] ` <1b153bce-a66a-45ee-a5c6-963ea6fb1c82.949ef384-8293-46b8-903f-40a477c056ae.c9179140-7138-467c-85e9-419e68c95bd4@emailsignatures365.codetwo.com>
[not found] ` <1b153bce-a66a-45ee-a5c6-963ea6fb1c82.0d2bd5fa-15cc-4b27-b94e-83614f9e5b38.02f2b6e0-f94c-4e13-b820-c0a2b10c9a96@emailsignatures365.codetwo.com>
2021-01-21 8:46 ` Mike Looijmans
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