I am using Omap3515 (Arm Cortex A8). Enabled I-Cache, D-Cache, Branch Prediction and MMU.
I am getting a data abort, if I try to copy a frame buffer of 600KB from an external memory region to another external memory region. After the data abort, I could notice that the SDR i.e SDRAM is not accessible.
I have enabled MMU in such a way that PA=VA.
There is no issue if I copy less amount data.
And also, If I disable D-Cache then there is no abort and it works fine. But I would like to enable D-Cache for faster access.
Thanks and regards,
Gopu
Hello,
Thanks for the reply. Here are the details.
Internal RAM slow :
This is due to the C bit and B bit settings in TLB of MMU. By mistake I have not enabled the cacheable and bufferable bit in the TLB. After enabling these bits. Internal RAM started working fine.
In OMAP 3515 internal ram is of 64 KB, I have tested a NEONCopyPLD of 47 KB from one region to another region it worked fine. i.e src = 0x40204000, dest = 0x40204400, size = 1024*47.
External RAM and abort :
This issue still exists. I want to copy 600KB from one region of SDRAM to another region of SDRAM. But it aborts if D Cache is enabled.
I tired 300KB, it works fine for some times. But for most of the times it goes to prefetch/data abort handler. And following are the status register values after the abort
Data Fault Status Register is 0
Instruction Fault Status Register is 0x1008
Instruction Fault Address Register is 0x80437314 (this is my code region)
Data Auxiliary Fault Status Register is 0
In the board we have single-data-rate LPSDR connected at the CS0 i.e from 0x80000000.
I am using only L1 address table in the MMU, and I did not enable L2 cache.
Hello Gopu,
how did you solve the problem which the internal RAM access was slower than the external RAM when MMU was enabled?
In case of successful case, how many data did you transferred?
Is it less that dcache size?
By the way, what is your computer board of OMAP 3515?
What is the LPDDR part?
Best regards,
Yasuhiko Koumoto.
View all questions in Cortex-A / A-Profile forum