Re: [PATCH RFT 2/3] media: i2c: dw9719: Add DW9800W support

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Hi Danila, Griffin,

On Tue, Aug 04, 2026 at 09:27:01PM +0300, Danila Tikhonov wrote:
> Hi Sakari,
> 
> Thank you for your comment.
> 
> On 04/08/2026 11:40, Sakari Ailus wrote:
> > Hi Danila,
> > 
> > Thank you for the patch.
> > 
> > On Sat, Aug 01, 2026 at 09:04:15PM +0300, Danila Tikhonov wrote:
> > > The DW9800W uses the same chip ID and register layout as the DW9800K,
> > > but requires different default VCM frequency value.
> > Is this a real difference between the two models or what fits for the
> > attached lens? Too bad the datasheet isn't publicly available. :-(
> > 
> > At least the differing default and constraints for dongwoon,vcm-prescale
> > needs to be documented in bindings.
> I share your skepticism and have essentially the same concerns. Since I
> do not have the DW9800K datasheet, I cannot say with certainty how it
> differs from the DW9800W.

Indeed. The limits should have been added for dw9800k, too, but I guess I
missed this in review. :-\

> 
> In particular, the parameter referred to as the VCM frequency in the
> driver is used to derive the SACT value. For the DW9800W, SACT[5:0]
> defines the actuator resonance period in SAC mode and the one-step
> period in LSC mode. The datasheet gives the corresponding formulas as:
> - tVIB = 6.3 ms + SACT * 0.1 ms
> - LSC 1-step period = 252 µs + SACT * 4 µs
> 
> Therefore, the default value may differ between the DW9800K and DW9800W
> if the formulas or timing characteristics used to calculate SACT are
> different.

Griffin, would you be able to comment this?

Another matter: the comment on dw9800k says there's no device ID. So is
there a device ID that wasn't just checked earlier or is there really no
device ID?

-- 
Regards,

Sakari Ailus