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From: eric@eukrea.com (Eric Bénard)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC] AT91 cpufreq support
Date: Wed, 30 Sep 2009 18:28:37 +0200	[thread overview]
Message-ID: <4AC38735.9020703@eukrea.com> (raw)
In-Reply-To: <4AC377CD.5020809@atmel.com>

Nicolas Ferre wrote :
> Anyway, as I see that there is a notifier for serial driver, I wonder if
> we can keep serial console connexion during frequency switching ? I
> assume that we will have to change the baud rate configuration of the
> terminal emulator but do you have a clue to give us (I tried without
> success) ?
> 
once called after the frequency change the notifier function in the 
serial driver updates uartclk and calls atmel_set_termios which should 
update the baudrate generator to the new master clock so you shouldn't 
need to change the baudrate.
To be clean, the serial port may need to be turned off before the 
frequency change in order to prevent garbage chars to be sent on the 
serial port as some USB serial adapters hang when receiving such garbage 
which may explain your problem.

Eric

  reply	other threads:[~2009-09-30 16:28 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-08-26 19:33 [RFC] AT91 cpufreq support Albin Tonnerre
2009-09-30 15:22 ` Nicolas Ferre
2009-09-30 16:28   ` Eric Bénard [this message]
2009-10-03 12:18     ` Albin Tonnerre

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