Re: [V5, 2/2] media: i2c: dw9768: Add DW9768 VCM driver

[Dongchun Zhu <dongchun.zhu@mediatek.com>]

Hi Sakari,

On Tue, 2020-05-12 at 11:58 +0300, Sakari Ailus wrote:
> Hi Dongchun,
> 
> On Tue, May 12, 2020 at 11:33:23AM +0800, Dongchun Zhu wrote:
> > Hi Tomasz,
> > 
> > On Mon, 2020-05-11 at 20:20 +0200, Tomasz Figa wrote:
> > > Hi Dongchun,
> > > 
> > > On Sat, May 9, 2020 at 4:25 AM Dongchun Zhu <dongchun.zhu@mediatek.com> wrote:
> > > >
> > > > Hi Sakari,
> > > >
> > > > On Sat, 2020-05-09 at 00:13 +0300, Sakari Ailus wrote:
> > > > > Hi Dongchun,
> > > > >
> > > > > On Fri, May 08, 2020 at 11:08:08AM +0800, Dongchun Zhu wrote:
> > > > > > Hi Sakari, Tomasz,
> > > > > >
> > > > > > Thanks for the review.
> > > > > >
> > > > > > On Thu, 2020-05-07 at 15:46 +0200, Tomasz Figa wrote:
> > > > > > > Hi Sakari, Dongchun,
> > > > > > >
> > > > > > > On Thu, May 7, 2020 at 3:12 PM Sakari Ailus
> > > > > > > <sakari.ailus@linux.intel.com> wrote:
> > > > > > > >
> > > > > > > > HI Dongchun,
> > > > > > > >
> > > > > > > > On Thu, May 07, 2020 at 08:45:24PM +0800, Dongchun Zhu wrote:
> > > > > > > > > Hi Sakari,
> > > > > > > > >
> > > > > > > > > Thanks for the review.
> > > > > > > > >
> > > > > > > > > On Wed, 2020-05-06 at 18:13 +0300, Sakari Ailus wrote:
> > > > > > > > > > Hi Dongchun,
> > > > > > > > > >
> > > > > > > > > > On Sun, May 03, 2020 at 12:17:27AM +0800, Dongchun Zhu wrote:
> > > > > > > > > > > Add a V4L2 sub-device driver for DW9768 voice coil motor, providing
> > > > > > > > > > > control to set the desired focus via IIC serial interface.
> > > > > > > > > > >
> > > > > > > > > > > Signed-off-by: Dongchun Zhu <dongchun.zhu@mediatek.com>
> > > > > > > > > > > ---
> > > > > > > > > > >  MAINTAINERS                |   1 +
> > > > > > > > > > >  drivers/media/i2c/Kconfig  |  11 ++
> > > > > > > > > > >  drivers/media/i2c/Makefile |   1 +
> > > > > > > > > > >  drivers/media/i2c/dw9768.c | 440 +++++++++++++++++++++++++++++++++++++++++++++
> > > > > > > > > > >  4 files changed, 453 insertions(+)
> > > > > > > > > > >  create mode 100644 drivers/media/i2c/dw9768.c
> > > > > > > > > > >
> > > > > > > > > > > diff --git a/MAINTAINERS b/MAINTAINERS
> > > > > > > > > > > index 8d72c41..c92dc99 100644
> > > > > > > > > > > --- a/MAINTAINERS
> > > > > > > > > > > +++ b/MAINTAINERS
> > > > > > > > > > > @@ -5157,6 +5157,7 @@ L:  linux-media@vger.kernel.org
> > > > > > > > > > >  S:       Maintained
> > > > > > > > > > >  T:       git git://linuxtv.org/media_tree.git
> > > > > > > > > > >  F:       Documentation/devicetree/bindings/media/i2c/dongwoon,dw9768.yaml
> > > > > > > > > > > +F:       drivers/media/i2c/dw9768.c
> > > > > > > > > > >
> > > > > > > > > > >  DONGWOON DW9807 LENS VOICE COIL DRIVER
> > > > > > > > > > >  M:       Sakari Ailus <sakari.ailus@linux.intel.com>
> > > > > > > > > > > diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> > > > > > > > > > > index 125d596..6a3f9da 100644
> > > > > > > > > > > --- a/drivers/media/i2c/Kconfig
> > > > > > > > > > > +++ b/drivers/media/i2c/Kconfig
> > > > > > > > > > > @@ -1040,6 +1040,17 @@ config VIDEO_DW9714
> > > > > > > > > > >     capability. This is designed for linear control of
> > > > > > > > > > >     voice coil motors, controlled via I2C serial interface.
> > > > > > > > > > >
> > > > > > > > > > > +config VIDEO_DW9768
> > > > > > > > > > > + tristate "DW9768 lens voice coil support"
> > > > > > > > > > > + depends on I2C && VIDEO_V4L2 && MEDIA_CONTROLLER
> > > > > > > > > > > + depends on VIDEO_V4L2_SUBDEV_API
> > > > > > > > > >
> > > > > > > > > > Please check how this works in the media tree master branch now --- it's
> > > > > > > > > > largely select based.
> > > > > > > > > >
> > > > > > > > >
> > > > > > > > > The actuator driver uses some structures that require the
> > > > > > > > > VIDEO_V4L2_SUBDEV_API code, so here we add VIDEO_V4L2_SUBDEV_API
> > > > > > > > > dependency to avoid possible build error when it's not enabled.
> > > > > > > >
> > > > > > > > Please make sure this works with current media tree master. Right now it
> > > > > > > > does not.
> > > > > > > >
> > > > > > >
> > > > > > > Dongchun, as Sakari said, please make sure to base the patches on the
> > > > > > > master branch of the media tree.
> > > > > > > (https://git.linuxtv.org/media_tree.git/). The approach for Kconfig
> > > > > > > dependency selection there seems to have changed recently.
> > > > > > >
> > > > > >
> > > > > > I searched the patches on the media tree master branch.
> > > > > > It seems that we need to remove the VIDEO_V4L2_SUBDEV_API dependency in
> > > > > > Kconfig, and add #ifdef CONFIG_VIDEO_V4L2_SUBDEV_API to include
> > > > > > v4l2-subdev code.
> > > > > > The change mainly is to make build pass, and don't return ENOTTY if
> > > > > > SUBDEV_API is not set.
> > > > > > Am I right?
> > > > >
> > > > > Please see Kconfig entries for other similar drivers from Dongwoon.
> > > > >
> > > >
> > > > Sorry for the mistake :-)
> > > > Just found the current media tree master branch code...
> > > > I would update Kconfig entries in next release by referring to:
> > > > https://git.linuxtv.org/media_tree.git/tree/drivers/media/i2c/Kconfig
> > > 
> > > Sorry for last minute comments again. We had a short discussion
> > > offline with Sakari and we think there are some changes needed to this
> > > driver, namely:
> > > 
> > > 1) The hardware being driven in our case is a gt9769, which could be
> > > compatible with dw9768, but it's still a different implementation and
> > > could have slightly different characteristics. Thus we think the
> > > driver name and compatible strings should be renamed from
> > > dongwoon,dw9768 to giantec,gt9769. In the future, if there is a device
> 
> Sorry, I actually meant just the compatible string --- Dongwoon is likely
> the original manufacturer. Therefore I'd name the driver according to that,
> and just add a second compatible string for the Giantec device.
> 
> Either works for me though.
> 

Just checked the legacy lens driver based on Mediatek architecture.
I found that both DW9718 and DW9719 have been using some configuration
registers to initialize VCM.
Unlickily, I cannot see any upstream patches about these two lens
drivers on the community.

For your suggestion, I think it is okay.
In fact, I just synced with Giantec FAE.
Dongwoon Anatech and Giantec are two different driver companies.
Their most VCM driver products are compatible with each other.
In fact, they have a mapping table of DW & GT.
For user, the actuator driver is common, such as DW9768 and GT9769.
However, algorithms inside the chip from different Manufactures differs.

For GT9769/DW9768, there is one read-only register 0x00 that could be
read out to distinguish VCM IC Manufacture ID.
The default value 0xE1 represents Giantec.

Finally I would add one more compatible for Giantec in next release.
Like this:
static const struct of_device_id dw9768_of_table[] = {
   { .compatible = "dongwoon,dw9768" },
   { .compatible = "giantec,gt9769" },
   {}
};
MODULE_DEVICE_TABLE(of, dw9768_of_table);

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