Hi again Laurent, --- On Fri, 7/23/10, P F <public_fil...@yahoo.com> wrote: > > Adding: > vma->vm_page_prot = > pgprot_noncached(vma->vm_page_prot); > to uvc_v4l2_mmap. This resolved the corruption. > gspca_zc3xx has the same > issue, and this patch worked there as well. >
I am happy to report that all instances of UVC JPEG corruption on my platform have been resolved. There were actually two sources of corruption, and I was encountering both of them. This may explain why debugging was so bewildering. One form of corruption was due to CPU starvation and not properly handling lost isochronous packets. Your patch here: http://lists.berlios.de/pipermail/linux-uvc-devel/2010-July/005824.html definitely resolved this for me. The other form of corruption is less well understood, but it was resolved by the change I described above. I have two pathological test cases which triggered these bugs. Unfortunately, the causes are totally independent, and I was seeing the "caching bug" when trying your isochronous patch, and thus saw no improvement. However, after resolving the "caching bug," I moved on to a different test case which revealed corruption again, and here your patch was the solution. I would like to ask you to push your patch upstream, and to investigate the efficacy of mine. I don't know anything about VMAs, but I know this works for me. Thank you very much for your assistance. I am happy to run further tests on my platform if you want. Best Regards _______________________________________________ Linux-uvc-devel mailing list Linux-uvc-devel@lists.berlios.de https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
