linux-kernel - Re: [PATCH v2 1/8] iio: accel: kx022a: Improve reset delay

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Message-ID: <20241123163443.678f063c@jic23-huawei>
Date: Sat, 23 Nov 2024 16:34:43 +0000
From: Jonathan Cameron <jic23@...nel.org>
To: Matti Vaittinen <mazziesaccount@...il.com>
Cc: Matti Vaittinen <matti.vaittinen@...rohmeurope.com>, Lars-Peter Clausen
 <lars@...afoo.de>, Rob Herring <robh@...nel.org>, Krzysztof Kozlowski
 <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>,
 linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/8] iio: accel: kx022a: Improve reset delay

On Thu, 21 Nov 2024 10:19:50 +0200
Matti Vaittinen <mazziesaccount@...il.com> wrote:

> All the sensors supported by kx022a driver seemed to require some delay
> after software reset to be operational again. More or less a random
> msleep(1) was added to cause the driver to go to sleep so the sensor has
> time to become operational again.
> 
> Now we have official docuumentation available:
> https://fscdn.rohm.com/kionix/en/document/AN010_KX022ACR-Z_Power-on_Procedure_E.pdf
> https://fscdn.rohm.com/kionix/en/document/TN027-Power-On-Procedure.pdf
> https://fscdn.rohm.com/kionix/en/document/AN011_KX134ACR-LBZ_Power-on_Procedure_E.pdf
> 
> stating the required time is 2 ms.
> 
> Due to the nature of the current msleep implementation, the msleep(1) is
> likely to be sleeping more than 2ms already - but the value "1" is
> misleading in case someone needs to optimize the start time and change
> the msleep to a more accurate delay. Hence it is better for
> "documentation" purposes to use value which actually reflects the
> specified 2ms wait time.
> 
> Change the value of delay after software reset to match the
> specifications and add links to the power-on procedure specifications.
> 
> Signed-off-by: Matti Vaittinen <mazziesaccount@...il.com>
Stands fine on it's own so applied (before I've even read the rest of the series).

Jonathan