Re: [PATCH v9 7/7] arm64: dts: qcom: sdm670-google-sargo: add imx355 front camera

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

Hi David, Richard,

On Tue, Mar 24, 2026 at 10:35:24AM +0100, David Heidelberg wrote:
> 
> 
> On 24/03/2026 03:05, Richard Acayan wrote:
> > On Fri, Mar 13, 2026 at 07:26:47PM +0100, David Heidelberg wrote:
> > > On 17/02/2026 01:27, Richard Acayan wrote:
> > > [...]
> > > 
> > > > +&cci_i2c1 {
> > > > +	camera@1a {
> > > > +		compatible = "sony,imx355";
> > > > +		reg = <0x1a>;
> > > > +
> > > > +		clocks = <&camcc CAM_CC_MCLK2_CLK>;
> > > > +
> > > > +		assigned-clocks = <&camcc CAM_CC_MCLK2_CLK>;
> > > > +		assigned-clock-rates = <19200000>;
> > > 
> > > Extract from #sdm670-mainline:erebion.eu discussion:
> > > The imx355 can operate on 24 MHz (on both Pixel 3 and 3a), but Linux kernel
> > > driver can operate only with 19.2 MHz.
> > > 
> > > I assume it would be worth it mention at least by comment here.
> > 
> > This might set the series back because the devicetree isn't meant to be
> > written for specific software, but it's included in v11 because you
> > already asked twice.
> > 
> 
> I would say node with lower clock frequency is still much better than
> nothing or placeholder saying "i2c camera here". Instead we'll have small
> placeholder that value can be bumped to 24 MHz. Important is this can be
> easily improved when at least one consumer of the device-tree gains support.
> 
> We have very scarce support of cameras on mobile phones in mainline, thus
> leaving a comment that HW can do 24 MHz is reasonable compromise IMHO.

The bindings could document the supported frequency range.

In DTS it may make sense to set the frequency the vendor uses as it may
affect the link frequencies (albeit I guess they're the same in this
case?).

> 
> I personally got confused why Android sets higher clock, thus it may happen
> to other people looking at Pixel 3a as an example for their imx363 bring-up.
> 
> David
> 
> > The frequency could also be stated as having "better software support"
> > in general without mentioning Linux as the reason.
> 

-- 
Regards,

Sakari Ailus