Hello.
Subbrathnam, Swaminathan wrote:
CPPI4.1 is an evolution over CPPI3.0.
I would call the 3.0-to-4.1 changes rather revolutionary, than
evolutionary...
As I see it the following features evolved compared to 3.0
1. List management functions are handled by the DMA engine in 4.1 compared to
3.0 were the SW (driver) managed the same.
True, descriptor queues are handled by the queue manager now.
2. New performance modes (Generic RNDIS) got introduced.
Those new modes don't have anything to do with CPPI 4.1 itself --
they're part of USB XFER DMA. I think TI could well have kept using CPPI
3.0 and just added the new modes...
Beyond that the general processing of the DMA descriptors and functionality are
very similar between CPPI3.0 and 4.1.
There's nothing similar in the descriptor formats, there was no DMA
controller, and neither queue nor buffer managers in CPPI 3.0.
regards
swami
________________________________________
From: [email protected]
[[email protected]] On Behalf Of Sergei
Shtylyov [[email protected]]
Sent: Friday, March 20, 2009 11:08 PM
To: David Brownell
Cc: [email protected];
[email protected]
Subject: Re: [PATCH] DaVinci: add support for CPPI 4.1
David Brownell wrote:
If this is only for the MUSB driver, it might be better to
stash this code in driver/usb/musb and generalize the
current CPPI glue there.
Generalize what? There's no way CPPI 3.0 and 4.1 can be "generalized",
they're too unlike.
If they're "too unlike" then they can't usefully connected
to the musb engine and yet both work ...
The difference being just 3.0 vs 4.1 might suggest that 4.1 is some sort
of superset to 3.0... but this is just not so -- everything is so completely
different between these specs, that I'm not sure why TI kept the same name.
WBR, Sergei
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