Re: [PATCH v11 4/7] media: qcom: camss: Add support to populate sub-devices

[Bryan O'Donoghue]

On 27/03/2026 22:48, Loic Poulain wrote:
> On Fri, Mar 27, 2026 at 11:37 PM Bryan O'Donoghue
> <bryan.odonoghue@xxxxxxxxxx> wrote:
> > On 27/03/2026 21:33, Dmitry Baryshkov wrote:
> > > > Other drivers typically call the populate function at the end of the
> > > > probe function. In this case, however, it is invoked before the main
> > > > resources are enabled. I assume this is because the CSIPHY device
> > > > needs to be available early. Aside from that, it looks good to me.
> > > This becomes fragile. The CSI PHY might be built as a module, which
> > > might be loaded later.
> > Is it any more or less fragile than "simple-mfd" in a DT though ?
> > Krzysztof isn't very much in favour of simple-mfd so this method of
> > population is the alternative to hand.
> >
> > The CSIPHY driver uses devm_of_phy_get which handles deferred probe. If
> > the PHY module isn't loaded yet when CAMSS tries to get it, CAMSS gets
> > -EPROBE_DEFER and retries.
> What about relying on v4l2_async_nf_register() in the same way as for
> the sensors? That would allow both the sensors and the CSIPHY to be
> bound asynchronously when they are ready, assuming the CSIPHY driver
> registers a V4L2 subdevice...

The point of +	devm_of_platform_populate(dev); or simple-mfd is to allow 
all sub-devices to asynchronously probe wrt the existing camss node.

OPE, IPE, BPS, ICP, CSIPHY - for the case of CSIPHY CAMSS cares about a 
phandle but for the others it does not.

There's no bug here to solve that devm_of_phy_get() doesn't solve.

---
bod