I've been working on CSI camera input and PXP color space conversions recently. I have to use EXTMEM frame buffers for VGA frames due to their size (614400 bytes) so I am concerned about cache efficiency and some of the problems that occur when both the CSI and PXP try to use EXTMEM at the same time. My current conclusion is that these two hardware blocks don't play nicely when both try to access EXTMEM at the same time.

While working on these issues, I realized that I didn't understand the ARM V7 data cache as well as I should. I found an excellent discussion of the cache at:


The link is to the first of three blog entries. I hope others wondering about cache operation will find it useful.