[libcamera-devel] [PATCH 3/7] libcamera: ipu3: imgu: Fix BDS height calculation

[Laurent Pinchart]

Hi Jacopo,

Thank you for the patch.

On Thu, Mar 18, 2021 at 11:39:37AM +0100, Jacopo Mondi wrote:
> The IF rectangle height is iteratively computed by first subtracting
> the scaling factor to the estimated height, then in a successive loop
> by adding the same scaling factor until the maximum IF size is not
> reached.
> 
> As the computed IF height is not cached in any variable, the second
> loop over-writes the result of the first one, even if the BDS alignment
> condition is not satisfied.
> 
> Fix this by caching the result of the two iterations, and use the one
> that produced any result, with a preference for the one produced by the
> second loop, as implemented in the reference python script.
> 
> Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
> ---
>  src/libcamera/pipeline/ipu3/imgu.cpp | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/src/libcamera/pipeline/ipu3/imgu.cpp b/src/libcamera/pipeline/ipu3/imgu.cpp
> index d9296ea3e674..11bb7cb95084 100644
> --- a/src/libcamera/pipeline/ipu3/imgu.cpp
> +++ b/src/libcamera/pipeline/ipu3/imgu.cpp
> @@ -129,10 +129,10 @@ void calculateBDSHeight(ImgUDevice::Pipe *pipe, const Size &iif, const Size &gdc
>  	float bdsHeight;
>  
>  	if (!isSameRatio(pipe->input, gdc)) {
> +		unsigned int foundIfHeights[2] = { 0, 0 };

You don't need two values, a single one will do, it can be overwritten
in the second loop.

With an updated commit message,

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

>  		float estIFHeight = (iif.width * gdc.height) /
>  				    static_cast<float>(gdc.width);
>  		estIFHeight = std::clamp<float>(estIFHeight, minIFHeight, iif.height);
> -		bool found = false;
>  
>  		ifHeight = utils::alignUp(estIFHeight, IF_ALIGN_H);
>  		while (ifHeight >= minIFHeight && ifHeight / bdsSF >= minBDSHeight) {
> @@ -142,7 +142,7 @@ void calculateBDSHeight(ImgUDevice::Pipe *pipe, const Size &iif, const Size &gdc
>  				unsigned int bdsIntHeight = static_cast<unsigned int>(bdsHeight);
>  
>  				if (!(bdsIntHeight % BDS_ALIGN_H)) {
> -					found = true;
> +					foundIfHeights[0] = ifHeight;
>  					break;
>  				}
>  			}
> @@ -158,7 +158,7 @@ void calculateBDSHeight(ImgUDevice::Pipe *pipe, const Size &iif, const Size &gdc
>  				unsigned int bdsIntHeight = static_cast<unsigned int>(bdsHeight);
>  
>  				if (!(bdsIntHeight % BDS_ALIGN_H)) {
> -					found = true;
> +					foundIfHeights[1] = ifHeight;
>  					break;
>  				}
>  			}
> @@ -166,7 +166,12 @@ void calculateBDSHeight(ImgUDevice::Pipe *pipe, const Size &iif, const Size &gdc
>  			ifHeight += IF_ALIGN_H;
>  		}
>  
> -		if (found) {
> +		if (foundIfHeights[0])
> +			ifHeight = foundIfHeights[0];
> +		if (foundIfHeights[1])
> +			ifHeight = foundIfHeights[1];
> +
> +		if (foundIfHeights[0] || foundIfHeights[1]) {
>  			unsigned int bdsIntHeight = static_cast<unsigned int>(bdsHeight);
>  
>  			pipeConfigs.push_back({ bdsSF, { iif.width, ifHeight },

-- 
Regards,

Laurent Pinchart