From: Feng Tang <feng.tang@intel.com>
To: christian pellegrin <chripell@fsfe.org>
Cc: "akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"greg@kroah.com" <greg@kroah.com>,
"david-b@pacbell.net" <david-b@pacbell.net>,
"grant.likely@secretlab.ca" <grant.likely@secretlab.ca>,
"alan@lxorguk.ukuu.org.uk" <alan@lxorguk.ukuu.org.uk>,
"spi-devel-general@lists.sourceforge.net"
<spi-devel-general@lists.sourceforge.net>,
"linux-serial@vger.kernel.org" <linux-serial@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1 3/4] max3100: adds console support for MAX3100
Date: Mon, 29 Mar 2010 15:06:42 +0800 [thread overview]
Message-ID: <20100329150642.4a94e78a@feng-i7> (raw)
In-Reply-To: <cabda6421003282311x78051e1eq38ada68f2553609e@mail.gmail.com>
On Mon, 29 Mar 2010 14:11:15 +0800
christian pellegrin <chripell@fsfe.org> wrote:
> > I modified the code a little and run it on our HW platform, it
> > really show some sigh of life: it can boots to console (the print
> > format is not so good), I can input command and it execute
> > correctly, but very slow, I type 3 characters and it takes about 2
> > seconds to echo back on screen and start the execution, and after
> > about 1 minute, the console hang there and input stopped to work.
>
> never seen such a behavior. Which platform are you using? Which SPI
> driver? Do you have a low level printk (printascii) that puts output
> somewhere else so I can send you a patch with some debugging output?
> Can you log in some other way (like via network) and see if the CPU
> load is at 100% for some reason?
Hi,
Our platform is Intel Moorestown platform, and use a spi controller core
from Designware (drivers/spi/dw_*.c). I know the problem may probably be
caused by my setting, but the dw_spi driver works fine with our own
3110 driver.
For debug method, sadly I don't get another output port yet, but if you
have some debug patch, that's great, it will help when I find another debug
output than max3110.
>
> >> + max3100_sr(s, tx, &rx);
> >
> > It doesn't handle received characters here? If the console is
> > printing out a bulk of message while user input some command, the
> > command may be ignored. Myself have met the same problem in our
> > driver.
> >
>
> yes but I think it's quite difficult to solve this problem in every
> case. Console output is massively used only on boot when the user is
> not supposed to type a lot.
It's difficult but not impossible, actually our driver checks every word
read back and handle it if it contains a valid data
>
> >> + if (next != s->console_tail) {
> >> + s->console_buf[next] = ch;
> >> + s->console_head = next;
> >> + }
> >
> > Also I saw max3100_sr() uses cpu_to_be16() and be16_to_cpu(), is it
> > really necessary, our platform is little-endian(x86), and I have to
> > disable them to make the code work. Is your test platform
> > big-endian?
> >
>
> Have you configured your SPI controller as LSB first somehow, haven't
> you? BTW my platform is a quite usual ARM9 S3C2440 which is little
> endian.
>
yeah, you hit the point that our spi controller is LSB naturally (not
configured to), here may need a check for whether to do a swap
next prev parent reply other threads:[~2010-03-29 7:01 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-23 10:29 [PATCH v1 0/3] max3100: improvements christian pellegrin
2010-03-23 10:28 ` [PATCH v1 1/4] max3100: added raise_threaded_irq Christian Pellegrin
2010-03-23 10:29 ` [PATCH v1 2/4] max3100: moved to threaded interrupt Christian Pellegrin
2010-03-23 10:29 ` [PATCH v1 3/4] max3100: adds console support for MAX3100 Christian Pellegrin
2010-03-29 2:48 ` Feng Tang
2010-03-29 6:11 ` christian pellegrin
2010-03-29 7:06 ` Feng Tang [this message]
2010-03-29 12:55 ` christian pellegrin
2010-04-08 9:31 ` christian pellegrin
2010-04-08 9:43 ` christian pellegrin
2010-03-23 10:29 ` [PATCH v1 4/4] max3100: introduced to_max3100_port, small style fixes Christian Pellegrin
2010-04-15 23:22 ` [PATCH v1 1/4] max3100: added raise_threaded_irq Thomas Gleixner
2010-04-16 16:18 ` christian pellegrin
2010-04-16 22:06 ` Thomas Gleixner
2010-04-17 16:25 ` christian pellegrin
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