Re: [BACKPORT v3.18] media: ov6650: Fix sensor possibly not detected on probe

[Janusz Krzysztofik <jmkrzyszt@gmail.com>]

Hi Greg,

On Saturday, March 30, 2019 6:47:12 AM CET Greg KH wrote:
> On Fri, Mar 29, 2019 at 10:20:05PM +0100, Janusz Krzysztofik wrote:
> > After removal of clock_start() from before soc_camera_init_i2c() in
> > soc_camera_probe() by commit 9aea470b399d ("[media] soc-camera: switch
> > I2C subdevice drivers to use v4l2-clk") introduced in v3.11, the ov6650
> > driver could no longer probe the sensor successfully because its clock
> > was no longer turned on in advance.  The issue was initially worked
> > around by adding that missing clock_start() equivalent to OMAP1 camera
> > interface driver - the only user of this sensor - but a propoer fix
> > should be rather implemented in the sensor driver code itself.
> > 
> > Fix the issue by inserting a delay between the clock is turned on and
> > the sensor I2C registers are read for the first time.
> > 
> > Fixes: 9aea470b399d ("[media] soc-camera: switch I2C subdevice drivers to 
use v4l2-clk")
> > Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
> > Cc: stable@vger.kernel.org
> > ---
> > Rebased on 3.18, should apply cleanly on 4.4 and 4.9 as well.
> > 
> > I dropped the comment on the patch being tested on an out of tree
> > omap1_camera driver mainly because that driver is still in the tree
> > in those kernel versions.
> > 
> >  drivers/media/i2c/soc_camera/ov6650.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/drivers/media/i2c/soc_camera/ov6650.c b/drivers/media/i2c/
soc_camera/ov6650.c
> > index ab01598ec83f..c0e25bf55fb8 100644
> > --- a/drivers/media/i2c/soc_camera/ov6650.c
> > +++ b/drivers/media/i2c/soc_camera/ov6650.c
> > @@ -829,6 +829,8 @@ static int ov6650_video_probe(struct i2c_client 
*client)
> >  	if (ret < 0)
> >  		return ret;
> >  
> > +	msleep(20);
> > +
> >  	/*
> >  	 * check and show product ID and manufacturer ID
> >  	 */
> 
> What is the git commit id of this patch in Linus's tree?

Not yet in Linus' tree, but already applied by Sakari Ailus in his 
https://git.linuxtv.org/sailus/media_tree.git/, 
id=cea17210dc0ee140289d900144662e70ea8aa623.

FYI, I submitted this backport in order to address the following request from 
the following automated off-list response to my original submission 
(https://www.spinics.net/lists/stable/msg293064.html).

> [This is an automated email]
> 
> This commit has been processed because it contains a "Fixes:" tag,
> fixing commit: 9aea470b399d [media] soc-camera: switch I2C subdevice drivers 
to use v4l2-clk.
> 
> The bot has tested the following trees: v5.0.4, v4.19.31, v4.14.108, 
v4.9.165, v4.4.177, v3.18.137.
> 
> v5.0.4: Build OK!
> v4.19.31: Build OK!
> v4.14.108: Build OK!
> v4.9.165: Failed to apply! Possible dependencies:
>     Unable to calculate
> 
> v4.4.177: Failed to apply! Possible dependencies:
>     Unable to calculate
> 
> v3.18.137: Failed to apply! Possible dependencies:
>     Unable to calculate
> 
> 
> How should we proceed with this patch?

The reason was the driver moved into a different directory in 4.14.

Inspired by your request, I've just learned how such info on original commit 
should be included in the commit message. I can resend with that added as soon 
as the patch lands in Linus' tree if you wish.

Thanks,
Janusz