Linux-OMAP Archive on
 help / color / Atom feed
From: Adam Ford <>
To: Linux-OMAP <>
Cc: Tero Kristo <>, Tony Lindgren <>
Subject: AM3517 MUSB and CPPI
Date: Sun, 17 May 2020 21:47:08 -0500
Message-ID: <> (raw)

From what I can tell, the MUSB controller on the AM3517 hasn't worked
in a very long time.

I have been going through the TRM for the AM3517, and I am convinced
the device tree for the OTG port is wrong, but I am struggling to fix

From what I can see the USB OTG Port support the CPPI 4.1 DMA
controller, but the CPPI 4.1 only appears to support the
DA850/OMAP-L138 and the AM335x family.

It appears as if the AM35xx is a bit closer in behavior to the AM335x
than the L138, but I was hoping either Tony, Tero or someone from TI
might have a suggestion.

The compatible flag need to be something like "compatible =
"ti,am35xx-musb" and not omap3, because OMAP3 doesn't support the CPPI
4.1 DMA controller and the AM3517 does.

Secondly, we need to update a couple of the tables in the cppi driver
to support the am3517, and lastly, the device tree node needs to
support the CPPI driver.

It looks like the DA850/L138 makes the CPPI driver a sub-node of the
OTG port, while the am335x has it as a separate node from the USB

From what I can tell on the AM3517, the CPPI DMA node should be a
sub-node of the OTG.

What I am struggling with now is the register offsets for controller,
scheduler and queue manager.
On both DA850 the 335x, there is an explicit table entry showing the
offset of DMAREVID, which tells the DMA revision ID.  I cannot find a
corresponding register for the AM3517, yet the AM3517

FWICT, the scheduler is offset 0x2000 with respect to the OTG
controller, and the Queue Manager register is at 0ffset 0x4000, both
with respect to the OTG base address.  Unfortunately, I am not finding
the offset for the CDMA controller itself.

Can someone tell me what it should be?  I am guessing it would be near
the 0x1000 offset, but it's a pure guess.


             reply index

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-18  2:47 Adam Ford [this message]
2020-05-18  5:35 ` Sekhar Nori
2020-05-18 10:19   ` Adam Ford
2020-05-19 15:42     ` Tony Lindgren
2020-05-21  2:44     ` Bin Liu
2020-05-22 10:16       ` Adam Ford

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='' \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-OMAP Archive on

Archives are clonable:
	git clone --mirror linux-omap/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-omap linux-omap/ \
	public-inbox-index linux-omap

Example config snippet for mirrors

Newsgroup available over NNTP:

AGPL code for this site: git clone