From: Anton Vorontsov <avorontsov@ru•mvista.com>
To: Laurent Pinchart <laurentp@cse-semaphore•com>
Cc: Scott Wood <scottwood@freescale•com>,
linuxppc-dev@ozlabs•org, linux-usb@vger•kernel.org,
David Brownell <david-b@pacbell•net>,
Timur Tabi <timur@freescale•com>
Subject: Re: [PATCH] Freescale QUICC Engine USB Host Controller
Date: Thu, 3 Apr 2008 18:30:52 +0400 [thread overview]
Message-ID: <20080403143052.GA5955@polina.dev.rtsoft.ru> (raw)
In-Reply-To: <200804031545.51834.laurentp@cse-semaphore.com>
On Thu, Apr 03, 2008 at 03:45:47PM +0200, Laurent Pinchart wrote:
> Hi Anton,
>
> On Tuesday 11 March 2008 20:17, Anton Vorontsov wrote:
> > This is patch adds support for the FHCI USB controller, as found
> > in the Freescale MPC836x and MPC832x processors. It can support
> > Full or Low speed modes.
> >
> > Quite a lot hardware is doing by itself (SOF generation, CRC generation
> > and checking), though scheduling and retransmission is on the software
> > shoulders.
> >
> > This controller does not integrate the root hub, so this driver also
> > fakes an one-port hub. External hub is required to support more than
> > one device.
>
> Would it be possible to use the driver for CPM2-based devices ?
Probably. But no one had tried this yet.
> The only
> difference I found between the CPM2 and QE USB controllers is the SOF
> handling. The QE USB controller increments the frame number itself, while the
> CPM USB controller requires the host to increment the frame number.
>
> At first sight the driver depends on qe_lib for:
>
> - muram allocation (qe_muram_alloc/free, qe_muram_offset/addr)
Yeah, I already posted a patch to deal with it, see
http://ozlabs.org/pipermail/linuxppc-dev/2008-March/053249.html
(btw... Scott, Timur did you have a chance to look into this?)
> - GPIO access (qe_gpio_set_dedicated)
This is because of David Brownell. ;-) Specifically, unwillingness to
accept that set_dedicated is portable for some scope of GPIO controllers,
as well as GPIO users.
> - clock routing (qe_clock_source, qe_usb_clock_set)
Well, there is Linux CLK API (somewhat similar to GPIO API), but PowerPC
doesn't use it yet. Neither I can tell if CLK API is suitable for our
needs, or if it needs to be extended. Quick&dirty workarounds are
still possible though, but clk api is the right way to go.
> - QE commands execution (qe_issue_cmd)
No proper solution yet.
> It shouldn't be too difficult to abstract those operation in a fashion similar
> to the cpm_uart driver.
Yup, but we still have ucc_serial (QE) and cpm_uart (CPM1/2) drivers as
separate matters though. ;-) I didn't look for the reasons of this split
but I assume there are and they're strong enough.
> Have you already worked on CPM2 support,
Nope, I don't have CPM2 board to work on.
> or thought about any particular issue
> I should pay attention to ?
Nope, sorry.
--
Anton Vorontsov
email: cboumailru@gmail•com
irc://irc.freenode.net/bd2
next prev parent reply other threads:[~2008-04-03 14:30 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-11 19:17 [PATCH] Freescale QUICC Engine USB Host Controller Anton Vorontsov
2008-03-11 21:32 ` Joakim Tjernlund
2008-04-03 13:45 ` Laurent Pinchart
2008-04-03 14:30 ` Anton Vorontsov [this message]
2008-04-03 15:27 ` Scott Wood
2008-04-03 15:33 ` Timur Tabi
2008-04-03 15:36 ` Scott Wood
2008-04-03 18:22 ` David Brownell
2008-04-07 16:11 ` Laurent Pinchart
2008-04-08 12:16 ` Anton Vorontsov
2008-04-09 12:13 ` Laurent Pinchart
2008-04-09 12:16 ` Pandita, Vikram
2008-04-09 12:20 ` Laurent Pinchart
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