linux-kernel - Re: [Patch v3 6/8] media: i2c: ov2659: Add powerdown/reset gpio handling

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Message-ID: <20190925095154.GL9467@paasikivi.fi.intel.com>
Date:   Wed, 25 Sep 2019 12:51:54 +0300
From:   Sakari Ailus <sakari.ailus@...ux.intel.com>
To:     Benoit Parrot <bparrot@...com>
Cc:     Hans Verkuil <hverkuil@...all.nl>,
        Prabhakar Lad <prabhakar.csengg@...il.com>,
        Rob Herring <robh+dt@...nel.org>, linux-media@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [Patch v3 6/8] media: i2c: ov2659: Add powerdown/reset gpio
 handling

Hi Benoit,

On Tue, Sep 24, 2019 at 11:44:12AM -0500, Benoit Parrot wrote:
> On some board it is possible that the sensor 'powerdown' and or 'reset'
> pin might be controlled by gpio instead of being tied.
> 
> To implement we add pm_runtime support which will handle the power
> up/down sequence when it is available otherwise the sensor will be
> powered on at module insertion/probe and powered off at module removal.
> 
> Now originally the driver assumed that the sensor would always stay
> powered and keep its register setting. We cannot assume this anymore, so
> every time we "power up" we need to re-program the initial registers
> configuration first. This was previously done only at probe time.
> 
> Signed-off-by: Benoit Parrot <bparrot@...com>

Thanks for the update.

I missed the control interface is accessible also when the device is not
streaming, and the driver doesn't appear to power on the sensor for that,
leading to a failing I²C write.

Could you address that as well, either here or as a separate patch? E.g.
the smiapp driver does this.

-- 
Kind regards,

Sakari Ailus
sakari.ailus@...ux.intel.com