Re: [PATCH v2 1/3] media: i2c: imx471: Add line length PCK setting

[Kate Hsuan]

Hi Sakari,

Thank you for reviewing this.

On Fri, Sep 4, 2026 at 4:32 PM Sakari Ailus <sakari.ailus@xxxxxx> wrote:
>
> On Fri, Sep 04, 2026 at 11:18:16AM +0300, Sakari Ailus wrote:
> > Hi Kate,
> >
> > On Fri, Sep 04, 2026 at 03:51:11PM +0800, Kate Hsuan wrote:
> > > Add the line length PCK setting to the IMX471 driver. This parameter
> > > determines the horizontal line scan duration and is used to calculate
> > > and control the sensor frame rate.
> > > Set the line length PCK value to 0x0a00 (matching the original value
> > > in ipu6-drivers), which maintains a frame rate close to the datasheet
> > > spec (~150 FPS in 2328x1304 binning mode).
> >
> > This fits on fewer lines, please rewrap.
Okay

> >
> > >
> > > Signed-off-by: Kate Hsuan <hpa@xxxxxxxxxx>
> > > ---
> > >  drivers/media/i2c/imx471.c | 2 ++
> > >  1 file changed, 2 insertions(+)
> > >
> > > diff --git a/drivers/media/i2c/imx471.c b/drivers/media/i2c/imx471.c
> > > index 4053aed84340..3c939f2a9056 100644
> > > --- a/drivers/media/i2c/imx471.c
> > > +++ b/drivers/media/i2c/imx471.c
> > > @@ -91,6 +91,7 @@
> > >  #define IMX471_CSI_2_LANE_MODE                     1
> > >  #define IMX471_CSI_4_LANE_MODE                     3
> > >
> > > +#define IMX471_REG_LINE_LENGTH_PCK         CCI_REG16(0x0342)
> > >  #define IMX471_REG_X_ADD_STA                       CCI_REG16(0x0344)
> > >  #define IMX471_REG_Y_ADD_STA                       CCI_REG16(0x0346)
> > >  #define IMX471_REG_X_ADD_END                       CCI_REG16(0x0348)
> > > @@ -240,6 +241,7 @@ static const struct cci_reg_sequence mode_1928x1088_regs[] = {
> > >     { CCI_REG8(0x030d), 0x02 },
> > >     { CCI_REG8(0x030e), 0x00 },
> > >     { CCI_REG8(0x030f), 0x53 },
> > > +   { IMX471_REG_LINE_LENGTH_PCK, 2560 },
> >
> > The register definition is nice but there's already a control for this.
> > Could you do this via s_ctrl()?
okay. I'll update the value when set V4L2_CID_HBLANK.

The original driver in the ipu6-drivers sets this register with 2560
and I found that a larger value slows down the fps. I try to make the
fps close to the datasheet.

> >
> > There's also another set addressing related issues here
> > <URL:https://lore.kernel.org/linux-media/20260904075113.125751-1-hpa@xxxxxxxxxx/T/#t>.
>
> Wrong URL, I meant this one
> <URL:https://patchwork.linuxtv.org/project/linux-media/patch/ede568ada4304d2dc92cd43986fc07aa68628154.1788377269.git.christian@xxxxxxxxxxxxx/>.
It's ok :)
Ah yes, I noticed that. We can discuss the pixel rate there.

>
> --
> Sakari Ailus
>


-- 
BR,
Kate