Re: [PATCH v4 02/21] media: i2c: imx355: Add support for 24 MHz external clock

[Sakari Ailus]

Hi Richard,

On Wed, Jul 15, 2026 at 03:47:41PM -0400, Richard Acayan wrote:
> On Wed, Jul 15, 2026 at 12:43:15PM +0100, Dave Stevenson wrote:
> > From: David Heidelberg <david@xxxxxxx>
> > 
> > The IMX355 sensor supports multiple external clock frequencies,
> > including 19.2 MHz and 24 MHz. The driver currently supports only
> > fixed 19.2 MHz input clock.
> > 
> > Refactor the clock handling to make the PLL configuration dependent
> > on the external clock frequency and add support for 24 MHz. Introduce
> > a table of clock parameter sets and program the corresponding EXTCLK
> > frequency and PLL multipliers to maintain consistent internal VCO
> > frequencies across supported inputs.
> > 
> > The PLL settings are adjusted so that OP VCO remains at 720 MHz
> > 
> > This preserves existing timing characteristics while allowing systems
> > using a 24 MHz clock to operate correctly.
> > 
> > No functional change for existing 19.2 MHz users.
> > 
> > Assisted-by: Claude:claude-opus-4-6
> > Signed-off-by: David Heidelberg <david@xxxxxxx>
> > Signed-off-by: Dave Stevenson <dave.stevenson@xxxxxxxxxxxxxxx>
> > ---
> >  drivers/media/i2c/imx355.c | 77 +++++++++++++++++++++++++++-------------------
> >  1 file changed, 45 insertions(+), 32 deletions(-)
> > 
> > diff --git a/drivers/media/i2c/imx355.c b/drivers/media/i2c/imx355.c
> > index ac59908f57aa..a6ee7532018f 100644
> > --- a/drivers/media/i2c/imx355.c
> > +++ b/drivers/media/i2c/imx355.c
> (snip)
> > @@ -1749,7 +1756,13 @@ static int imx355_probe(struct i2c_client *client)
> >  				     "failed to get clock\n");
> >  
> >  	freq = clk_get_rate(imx355->clk);
> > -	if (freq != IMX355_EXT_CLK)
> > +	for (unsigned int i = 0; i < ARRAY_SIZE(imx355_clk_params); i++) {
> 
> Did we start allowing variable declarations mixed with code?

C didn't allow that until somewhat recently, hence it hasn't been used in
the kernel either.

In cases like the above it improves readability. E.g. with __free() that is
also the recommended pattern.

-- 
Regards,

Sakari Ailus