[v2] debayer_egl: Use untransposed matrix to fix GLES 2.0
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Message ID 20260829142709.222649-1-robert.mader@collabora.com
State New
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Series
  • [v2] debayer_egl: Use untransposed matrix to fix GLES 2.0
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Commit Message

Robert Mader Aug. 29, 2026, 2:27 p.m. UTC 
The softISP curently fails on Mali-400 on Mesa. It turns out that
transposed matrices are not allowed by the spec:
> The UniformMatrix{234}fv commands will load count 2 × 2, 3 × 3, or 4 × 4
> matrices (corresponding to 2, 3, or 4 in the command name) of floating-point values
> into a uniform location defined as a matrix or an array of matrices. The matrix is
> specified in column-major order. transpose must be FALSE.

Thus partially revert the commit mentioned below and manually transpose
the matrix.

Fixes: d780e285b593 ("shaders: bayer: Use native matrix multiplication")
Closes: https://gitlab.freedesktop.org/camera/libcamera/-/work_items/342
Signed-off-by: Robert Mader <robert.mader@collabora.com>

---

Changes in v2:
 - Actually transpose the matrix to not re-introduce issues with CCMs
 - Add comment about GLES 2.0
 - Add "Closes:" link
---
 src/libcamera/software_isp/debayer_egl.cpp | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

Patch
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diff --git a/src/libcamera/software_isp/debayer_egl.cpp b/src/libcamera/software_isp/debayer_egl.cpp
index 97aa03793574..6df1ce1a8fb6 100644
--- a/src/libcamera/software_isp/debayer_egl.cpp
+++ b/src/libcamera/software_isp/debayer_egl.cpp
@@ -460,8 +460,21 @@  void DebayerEGL::setShaderVariableValues(eGLImage &eglImageIn, const DebayerPara
 			    << " textureUniformStep_.y " << Step[1]
 			    << " textureUniformStrideFactor_ " << Stride
 			    << " textureUniformProjMatrix_ " << textureUniformProjMatrix_;
-
-	glUniformMatrix3fv(ccmUniformDataIn_, 1, GL_TRUE, params.combinedMatrix.data().data());
+	/*
+	 * Pre-transpose matrix for GLES 2.0
+	 */
+	GLfloat ccm[9] = {
+		params.combinedMatrix[0][0],
+		params.combinedMatrix[1][0],
+		params.combinedMatrix[2][0],
+		params.combinedMatrix[0][1],
+		params.combinedMatrix[1][1],
+		params.combinedMatrix[2][1],
+		params.combinedMatrix[0][2],
+		params.combinedMatrix[1][2],
+		params.combinedMatrix[2][2],
+	};
+	glUniformMatrix3fv(ccmUniformDataIn_, 1, GL_FALSE, ccm);
 	LOG(Debayer, Debug) << " ccmUniformDataIn_ " << ccmUniformDataIn_ << " data " << params.combinedMatrix;
 
 	/*