Re: em28xx + ov2640 and v4l2-clk

["Frank Schäfer" <fschaefer.oss@googlemail.com>]

Am 08.10.2013 18:38, schrieb Guennadi Liakhovetski:
> Hi Frank,
>
> On Tue, 8 Oct 2013, Frank SchÀfer wrote:
>
>> Am 18.08.2013 17:20, schrieb Mauro Carvalho Chehab:
>>> Em Sun, 18 Aug 2013 13:40:25 +0200
>>> Frank SchÀfer <fschaefer.oss@googlemail.com> escreveu:
>>>
>>>> Am 17.08.2013 12:51, schrieb Guennadi Liakhovetski:
>>>>> Hi Frank,
>>>>> As I mentioned on the list, I'm currently on a holiday, so, replying briefly. 
>>>> Sorry, I missed that (can't read all mails on the list).
>>>>
>>>>> Since em28xx is a USB device, I conclude, that it's supplying clock to its components including the ov2640 sensor. So, yes, I think the driver should export a V4L2 clock.
>>>> Ok, so it's mandatory on purpose ?
>>>> I'll take a deeper into the v4l2-clk code and the
>>>> em28xx/ov2640/soc-camera interaction this week.
>>>> Have a nice holiday !
>>> commit 9aea470b399d797e88be08985c489855759c6c60
>>> Author: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
>>> Date:   Fri Dec 21 13:01:55 2012 -0300
>>>
>>>     [media] soc-camera: switch I2C subdevice drivers to use v4l2-clk
>>>     
>>>     Instead of centrally enabling and disabling subdevice master clocks in
>>>     soc-camera core, let subdevice drivers do that themselves, using the
>>>     V4L2 clock API and soc-camera convenience wrappers.
>>>     
>>>     Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
>>>     Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
>>>     Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
>>>     Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
>>>
>>>
>>> (c/c the ones that acked with this broken changeset)
>>>
>>> We need to fix it ASAP or to revert the ov2640 changes, as some em28xx
>>> cameras are currently broken on 3.10.
>>>
>>> I'll also reject other ports to the async API if the drivers are
>>> used outside an embedded driver, as no PC driver currently defines 
>>> any clock source. The same applies to regulators.
>>>
>>> Guennadi,
>>>
>>> Next time, please check if the i2c drivers are used outside soc_camera
>>> and apply the fixes where needed, as no regressions are allowed.
>>>
>>> Regards,
>>> Mauro
>> FYI: 8 weeks have passed by now and this regression has still not been
>> fixed.
>> Does anybody care about it ? WONTFIX ?
> You replied to my patch "em28xx: balance subdevice power-off calls" with a 
> few non-essential IMHO comments but you didn't test it.

Non-essential comments ?
Maybe you disagree or don't care about them, but that's something different.

> Could you test, please?

Yes, this patch will make the warnings disappear and works at least for
my em28xx+ov2640 device.
What about Mauros an my concerns with regards to all other em28xx devices ?
And what about the em28xx v4l2-clk patches ?

It's pretty simple: someone (usually the maintainer ;) ) needs to decide
which way to go.
Either accept and apply the existing patches or request new ones with
changes.
But IMHO doing nothing for 2 months isn't the right way to handle
regressions.

Regards,
Frank

> In the meantime I'm still waiting for more comments to my "[RFD] 
> use-counting V4L2 clocks" mail, so far only Sylwester has replied. Without 
> all these we don't seem to progress very well.
>
> Thanks
> Guennadi
>
>>>>> -----Original Message-----
>>>>> From: "Frank SchÀfer" <fschaefer.oss@googlemail.com>
>>>>> To: Guennadi Liakhovetski <g.liakhovetski@gmx.de>, Linux Media Mailing List <linux-media@vger.kernel.org>
>>>>> Sent: Fr., 16 Aug 2013 21:03
>>>>> Subject: em28xx + ov2640 and v4l2-clk
>>>>>
>>>>> Hi Guennadi,
>>>>>
>>>>> since commit 9aea470b399d797e88be08985c489855759c6c60 "soc-camera:
>>>>> switch I2C subdevice drivers to use v4l2-clk", the em28xx driver fails
>>>>> to register the ov2640 subdevice (if needed).
>>>>> The reason is that v4l2_clk_get() fails in ov2640_probe().
>>>>> Does the em28xx driver have to register a (pseudo ?) clock first ?
>>>>>
>>>>> Regards,
>>>>> Frank
> ---
> Guennadi Liakhovetski, Ph.D.
> Freelance Open-Source Software Developer
> http://www.open-technology.de/
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