Re: [RFC PATCH v1] media: rppx1: hist: Adjust configured LAST_MEAS_LINE

[Niklas Söderlund]

Hi Barnabás,

Thanks for your work.

On 2026-10-26 15:52:23 +0100, Barnabás Pőcze wrote:
> The `LAST_MEAS_LINE` parameter determines at the end of which line the
> interrupt is generated. The documentation states that it is usually
> configured to the last line of the measurement window.
> 
> Currently it is programmed such that there is a margin of 2 lines after
> the last measured line. This is more than what is required by the
> documentation. So change it to the documentation suggested value.
> 
> Note, that this is in contrast to the "exm" module, where the last line
> needs a margin of two lines on account of the division that is carried
> out when calculating the average.
> 
> Signed-off-by: Barnabás Pőcze <barnabas.pocze+renesas@xxxxxxxxxxxxxxxx>
> ---
> 
> While this has worked in my testing, I'm sending this as an RFC because I'm
> not sure if this is maybe a copy-paste issue from the "exm" module or if
> someone has noticed scenarios where reality contradicts the documentation.

I have re-checked the documentation and my notes, and most likely this 
is a copy-paste issue from the exm module. Thanks for fixing this. I 
have ran this thru my CI on SparrowHawk and no regressions detected.

Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>

> 
> ---
>  drivers/media/platform/dreamchip/rppx1/rppx1_hist.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/media/platform/dreamchip/rppx1/rppx1_hist.c b/drivers/media/platform/dreamchip/rppx1/rppx1_hist.c
> index 8fe8cbbc85df7..af82f31e4c86c 100644
> --- a/drivers/media/platform/dreamchip/rppx1/rppx1_hist.c
> +++ b/drivers/media/platform/dreamchip/rppx1/rppx1_hist.c
> @@ -128,7 +128,7 @@ static int rppx1_hist_fill_params(struct rpp_module *mod,
>  	 * Set last measurement line for ready interrupt. Ignore the value
>  	 * from the parameters as it is only useful for fast-channel switching.
>  	 */
> -	write(priv, mod->base + HIST_LAST_MEAS_LINE_REG, v_offs + v_size + 1);
> +	write(priv, mod->base + HIST_LAST_MEAS_LINE_REG, v_offs + v_size - 1);
>  
>  	/* Set measurement window weights. */
>  	write(priv, mod->base + HIST_WEIGHT_00TO30_REG,
> -- 
> 2.56.0
> 

-- 
Kind Regards,
Niklas Söderlund