From: Sascha Hauer <s.hauer@pengutronix.de>
To: Juergen Beisert <jbe@pengutronix.de>
Cc: barebox@lists.infradead.org
Subject: Re: [RFC] ARM/serial: add a DCC based console driver
Date: Tue, 13 Mar 2012 14:24:55 +0100 [thread overview]
Message-ID: <20120313132455.GE3852@pengutronix.de> (raw)
In-Reply-To: <201203131416.47776.jbe@pengutronix.de>
On Tue, Mar 13, 2012 at 02:16:46PM +0100, Juergen Beisert wrote:
> Hi,
>
> please find attached an DCC based driver for Barebox to be able to get early
> boot messages. It acts as a regular serial console and can be used in
> conjunction with a JTAG debugger. This is really useful when no serial
> console is available (don't ask why...) and the bootloader hangs prior it can
> enable a network based console.
>
> One issue is still present and I need some hints what might be going wrong
> here:
>
> Sending chars via DCC blocks for ever, when I'm using a simple
> while loop waiting for the DCC_OUTPUT_BUSY to be cleared. After adding a
> timeout loop I receive every other char at the JTAG side. When I write the
> char to the DCC even if it timeout, I receive *every* char. Only some chars
> are lost when I reduce the timeout value below 750 us.
> Any idea? I checked the kernel source, but they doing the same: Waiting for
> the DCC_OUTPUT_BUSY to be cleared and timeout after a specific amount of
> loops (but without writing the char in this case).
>
> Comments are welcome.
You are probably not aware that we already have such a driver in
drivers/serial/arm_dcc.c.
Sascha
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next prev parent reply other threads:[~2012-03-13 13:25 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-13 13:16 Juergen Beisert
2012-03-13 13:24 ` Sascha Hauer [this message]
2012-03-13 13:32 ` Juergen Beisert
2012-03-13 13:25 ` Juergen Beisert
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