Re: [PATCH v5 2/2] media: i2c: Add Sony IMX908 image sensor driver

[Sakari Ailus]

Hi Dave, Laurent,

On Tue, Oct 20, 2026 at 03:50:09PM +0100, Dave Stevenson wrote:
> Hi Sakari and Laurent
> 
> On Tue, 20 Oct 2026 at 13:56, Laurent Pinchart
> <laurent.pinchart@xxxxxxxxxxxxxxxx> wrote:
> >
> > Hello Sakari,
> >
> > On Tue, Oct 20, 2026 at 01:47:11PM +0300, Sakari Ailus wrote:
> > > On Mon, Oct 19, 2026 at 10:47:20AM +0900, Lachlan Michael wrote:
> > > > The IMX908 is an 8.39 MP (3856x2176) CMOS image sensor with a MIPI CSI-2
> > > > output interface. The driver supports RAW10 and RAW12 output formats,
> > > > exposure and analogue gain controls, image flipping, blanking controls
> > > > and test pattern generation.
> > >
> > > The imx908 appears to be a Starvis 3 sensor. How close is it to the Starvis
> > > 2, for which Dave (Cc'd) is working on a driver (see
> > > <URL:https://lore.kernel.org/linux-media/atdAsDGw_jvhaydM@kekkonen.localdomain/T/#m0c50ea017ef9ae0d3d76a36b840db9b6f7ac296c>)?
> > > The register defines in the two drivers appear to be quite well aligned.
> 
> Asked and answered at v1
> https://lore.kernel.org/linux-media/TY6PR01MB17839FF48671E744E7E23A93E92D42@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
> 
> > The current version of the driver implements very few features of the
> > IMX908 sensor, as crop support has been removed pending the raw camera
> > sensor model, and Clear HDR3 is being developed. I expect more
> > differences to appear when those features will be merged, so I believe
> > it makes sense to have a separate driver here.
> >
> > In the future, I expect the raw camera sensor model to open the door to
> > more code sharing and more drivers supporting a wider variety of
> > devices. We can decide then if the imx908 should stay a standalone
> > driver, support other sensors as well, possibly across the Starvis 2 and
> > 3 families. I'm willing to help with the refactoring at that point if
> > needed, the maintenance burden won't be on you (and I'm sure that
> > Lachlan and his team will of course maintain the code base).
> 
> Agreed.
> I have compared the datasheet for imx908 against the Starvis2 ones,
> and when we start looking at HDR modes they diverge a reasonable
> amount.
> 
> Even the later Starvis2 sensors (IMX585 and IMX676) have minor changes
> to the earlier ones, so adding Starvis3 would need some care.

There's quite a bit of this in the CCS driver, due to the variance it
allows for implementors. I don't see this being a problem as long as the
foundations are reasonably similar, albeit we can see whether this could be
further extended later on to other sensors.

I'm fine with having a separate imx908 driver for now. Dave's driver also
exposes the variant information through the media entity name so that
should be done by the imx908, too (at least if there can be multiple ones).

I'll review the driver properly soonish but I reckon it's in a pretty good
shape already.

-- 
Regards,

Sakari Ailus