From: Mike Rapoport <mike@compulab•co.il>
To: Laurent Pinchart <laurent.pinchart@tbox•biz>
Cc: linuxppc-embedded@ozlabs•org
Subject: Re: CPM2 USB driver & MPC8248
Date: Tue, 07 Feb 2006 16:20:35 +0200 [thread overview]
Message-ID: <43E8ACB3.6030401@compulab.co.il> (raw)
In-Reply-To: <200602071414.28551.laurent.pinchart@tbox.biz>
Laurent Pinchart wrote:
>How is the driver development going ? You're not using the sourceforge CVS/SVN
>repository, is there another one somewhere (maybe a git tree) ? Are you
>actively working on performance issues, or is the development currently
>stalled ?
>
>
The driver development is stalled and I don't know when I'll be able to
continue working on it.
>What are the major performance issues ?
>
>
One of the issues in this driver is redunduncy between qe end ep
structures and as a consequence a lot of uneeded code that make cross
updates.
I didn't run profiling, so I can't tell better.
>I noticed that the driver uses the MPC82xx packet level interface.
>Why don't you use the transaction level interface ?
>
>
The original driver I've started with used packet level. I thought on
switching to transaction level, but I hadn't time for it because of
other projects pressure.
>
>
>>Another thing that may cause problems is how storage devices treat SOF
>>packets, but I'm not USB expert enough to be sure about that.
>>
>>
>
>That might explain why some devices don't even respond to the first request. I
>noticed that, on my EP8248 board, the controller only sends 990 SOF packets
>per second (or rather 990 SOF interrupts are generated). I might have a time
>base problem somewhere, as I computed the number of interrupts per second
>with a simple
>
>cat /proc/driver/m8xxhci_privateh > sof.1 && sleep 300 &&
>cat /proc/driver/m8xxhci_privateh > sof.2
>
>
>
I'm not sure such measurements are correct, since you sleep not exatly
300 seconds. I haven't measured how many SOF interrupts I get, but I
think you maybe right.
It may happen that during transmit or recieve the interrupts are off and
SOF packets are not sent.
>Do you have the same problem ? I'll see if I can get my hands on a USB
>protocol analyzer.
>
>
Good luck, I'll try to help but unfotunately I'm very much busy with
other projects now.
>Laurent Pinchart
>
>
>
>
>
--
Sincerely yours,
Mike Rapoport
next prev parent reply other threads:[~2006-02-07 14:18 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-02-03 11:10 CPM2 USB driver & MPC8248 Laurent Pinchart
2006-02-03 11:34 ` Laurent Pinchart
2006-02-03 13:11 ` Alexandre BASTOS
2006-02-03 12:46 ` Laurent Pinchart
2006-02-03 15:53 ` Alex BASTOS
2006-02-05 8:44 ` Mike Rapoport
2006-02-07 13:14 ` Laurent Pinchart
2006-02-07 14:20 ` Mike Rapoport [this message]
2006-02-07 14:33 ` Laurent Pinchart
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