GPMC burst with EDMA

Gokhan Cosgul50

We are using GPMC in synchronous mode and using EDMA for burst transactions.

Here is what we see

Burst write sizes of

4-bytes, 8-bytes, 16-bytes, 32-bytes are OK.

However, if we try to write 40-bytes(20 words) we see a 32-bytes(16-words) write followed by a 16-bytes(8-words) write, where first 8-bytes are

our data and rest are FFFFs. We expect a 32-bytes + 8-bytes only but it does not happen.

Any suggestions?

over 9 years ago

0 Biser Gatchev-XID over 9 years ago

TI__Guru**** 393215 points

Hi,

Please check sections 7.1.2.3.6 and 7.1.2.3.10.5 from the AM335x TRM Rev. N.

0 Gokhan Cosgul50 over 9 years ago in reply to Biser Gatchev-XID

Prodigy 20 points

Thanks Biser,

I see that:

Only linear burst transactions are supported; interleaved burst transactions are not supported. Only powerof-
two-length precise bursts 2 × 32, 4 × 32, 8 × 32 or 16 × 32 with the burst base address aligned on the
total burst size are supported (this limitation applies to incrementing bursts only).

I am still not clear why 48-byte burst is correct? What we see is 16x16 (8x32) followed by 8x16(?) burst.

Gokhan

Processors

Processors forum

GPMC burst with EDMA