But pdfviewer also uses a library libpbframework which should also be licensed under GPL compatible license. Since its source is closed, there is a license violation.
Please consider removing pdfviewer application from your firmware or provide the source code of libpbframework and all its dependencies under GPL-compatible license.
PdfViewer application uses GPL licensed component "Poppler". http://cgit.freedesktop.org/poppler/poppler/tree/README As stated in /pdfviewer/COPYING it is also licensed under GPL.
But pdfviewer also uses a library libpbframework which should also be licensed under GPL compatible license. Since its source is closed, there is a license violation.
Please consider removing pdfviewer application from your firmware or provide the source code of libpbframework and all its dependencies under GPL-compatible license.