From: christian pellegrin <chripell@fsfe.org>
To: Feng Tang <feng.tang@intel.com>
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 08:11:15 +0200 [thread overview]
Message-ID: <cabda6421003282311x78051e1eq38ada68f2553609e@mail.gmail.com> (raw)
In-Reply-To: <20100329104838.49c18075@feng-i7>
On Mon, Mar 29, 2010 at 4:48 AM, Feng Tang <feng.tang@intel.com> wrote:
> Hi,
Hi,
>
> 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?
>> This patch adds console support for the MAX3100 UART
>> (console=ttyMAX0,11500). The SPI subsystem and an
>
> 115200?
>
ack
> Does this imply to have to work with HW flow control? on my platform
> I have to remove the RTS bit to make it work.
>
no, I put RTS on because it looks like a good default. I can make it
configurable. I just noticed on the data sheet that RTS is actually
inverted so a more sensible default would be to put it off. For
testing you should have flow control set to none on the machine you
are using as a terminal emulator.
>> + 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.
>> + 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.
--
Christian Pellegrin, see http://www.evolware.org/chri/
"Real Programmers don't play tennis, or any other sport which requires
you to change clothes. Mountain climbing is OK, and Real Programmers
wear their climbing boots to work in case a mountain should suddenly
spring up in the middle of the computer room."
next prev parent reply other threads:[~2010-03-29 6:11 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 [this message]
2010-03-29 7:06 ` Feng Tang
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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