From: Luca Ceresoli <luca@lucaceresoli.net>
To: Sakari Ailus <sakari.ailus@iki.fi>
Cc: Sowjanya Komatineni <skomatineni@nvidia.com>,
thierry.reding@gmail.com, jonathanh@nvidia.com,
hverkuil@xs4all.nl, jacopo+renesas@jmondi.org,
leonl@leopardimaging.com, robh+dt@kernel.org,
lgirdwood@gmail.com, broonie@kernel.org,
linux-media@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 2/3] media: i2c: imx274: Remove stop stream i2c writes during remove
Date: Thu, 24 Sep 2020 12:09:22 +0200 [thread overview]
Message-ID: <b243afda-b00f-4c0e-2eea-cc5d03cbebe7@lucaceresoli.net> (raw)
In-Reply-To: <20200922084746.GA8644@valkosipuli.retiisi.org.uk>
On 22/09/20 10:47, Sakari Ailus wrote:
> Hi Luca,
>
> On Tue, Sep 22, 2020 at 10:09:33AM +0200, Luca Ceresoli wrote:
>> Hi,
>>
>> On 21/09/20 23:39, Sowjanya Komatineni wrote:
>>> Sensor should already be in standby during remove and there is no
>>> need to configure sensor registers for stream stop.
>>
>> I beg your pardon for the newbie question: does the V4L2 framework
>> guarantee that the stream is stopped (.s_stream(..., 0)) before removing
>> the driver?
>
> It doesn't. That's however one of the lesser concerns, and I don't think
> it'd help if drivers tried to prepare for that.
Thanks for the clarification.
I've been working with hardware where the sensor is always powered. In
this case, and with this patch applied, the sensor would keep producing
frames after driver removal. This looks wrong, unless I'm overlooking
something.
BTW at first sight it looks like the framework should take care of
stopping the stream before removal, not the individual drivers, but
maybe there are good reasons this is not done?
--
Luca
next prev parent reply other threads:[~2020-09-24 10:09 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-21 21:39 [PATCH v6 0/3] IMX274 fixes and power on and off implementation Sowjanya Komatineni
2020-09-21 21:39 ` [PATCH v6 1/3] media: i2c: imx274: Fix Y_OUT_SIZE register setting Sowjanya Komatineni
2020-09-22 7:55 ` Thierry Reding
2020-09-21 21:39 ` [PATCH v6 2/3] media: i2c: imx274: Remove stop stream i2c writes during remove Sowjanya Komatineni
2020-09-22 7:55 ` Thierry Reding
2020-09-22 8:09 ` Luca Ceresoli
2020-09-22 8:47 ` Sakari Ailus
2020-09-24 10:09 ` Luca Ceresoli [this message]
2020-09-24 17:24 ` Sakari Ailus
2020-09-21 21:39 ` [PATCH v6 3/3] media: i2c: imx274: Add IMX274 power on and off sequence Sowjanya Komatineni
2020-09-22 7:55 ` Thierry Reding
2020-09-22 10:57 ` Jacopo Mondi
2020-09-22 16:13 ` Sowjanya Komatineni
2020-09-22 16:20 ` Sakari Ailus
2020-09-23 8:07 ` Thierry Reding
2020-09-23 8:30 ` Sakari Ailus
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