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From: Juergen Beisert <jbe@pengutronix.de>
To: barebox@lists.infradead.org
Subject: Re: [RFC] ARM/serial: add a DCC based console driver
Date: Tue, 13 Mar 2012 14:25:49 +0100	[thread overview]
Message-ID: <201203131425.49344.jbe@pengutronix.de> (raw)
In-Reply-To: <201203131416.47776.jbe@pengutronix.de>

Myself wrote:
> [...]
> 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).
> [...]

Forget about that. The dcc_serial_putc() is broken in this patch. My ARMv5 
*always* signals a DCC_OUTPUT_BUSY. If I ignore this bit and just wait about 
750 µs between the chars it works as expected. Still have to find out, why it 
always signals a DCC_OUTPUT_BUSY...

jbe

-- 
Pengutronix e.K.                              | Juergen Beisert             |
Linux Solutions for Science and Industry      | http://www.pengutronix.de/  |

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      parent reply	other threads:[~2012-03-13 13:26 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-03-13 13:16 [RFC] ARM/serial: add a DCC based console driver Juergen Beisert
2012-03-13 13:24 ` Sascha Hauer
2012-03-13 13:32   ` Juergen Beisert
2012-03-13 13:25 ` Juergen Beisert [this message]

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