Packet DMA Does Not Update RX PS Region Location Bit Usage Note

Hi Virendra,

Thanks for your post.

Yes, it is a generic bug which is not specific to any scenario but this issue affects only host type packets . Actually, the packet DMA module would fail to update the PS region location bit (bit 22 of packet descriptor word) to 1 when it tries to write an Rx. host-mode packet to memory which is located in the start of the data buffer instead of the descriptor. So, you could use monolithic packets instead of host type packets to overcome this issue as a tentative workaround.

You could also try other workaround which is to place the PS info. in the descriptor instead of the data buffer so that the PS location bit is always 0 and the issue is not applicable to this case.

Also, you could think of the software which can be designed to keep track of the PS info. location so it does not have to rely on the bit in the RX packet descriptor and the software can always use the same PS location setting which would eliminate to find out the location from the Rx. descriptor.

Alternatively, the software could place some form of identifier in any of the user-defined tag fields in the TX descriptor and configure the Packet DMA to pass that information through to the RX descriptor. You could try these workarounds which would suit you probably.

I believe, the above issue affects only silicon revisions 1.0, 1.1 and it is fixed in PG2.0. Please check 66AK2H06/12/14 silicon errata (sprz402b.pdf) doc and see "KeyStoneII.BTS_errata_usagenote.13"

http://www.ti.com/lit/er/sprz402b/sprz402b.pdf

Thanks & regards,

Sivaraj K

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