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From: Kevin Hilman <khilman@deeprootsystems.com>
To: "Pandita, Vikram" <vikram.pandita@ti.com>
Cc: Steve Sakoman <sakoman@gmail.com>,
	Robert Nelson <robertcnelson@gmail.com>,
	"linux-omap@vger.kernel.org" <linux-omap@vger.kernel.org>
Subject: Re: serial port input corruption with 2.6.32?
Date: Wed, 06 Jan 2010 16:25:09 -0800	[thread overview]
Message-ID: <874omy92xm.fsf@deeprootsystems.com> (raw)
In-Reply-To: <FCCFB4CDC6E5564B9182F639FC3560870300519479@dbde02.ent.ti.com> (Vikram Pandita's message of "Thu\, 7 Jan 2010 05\:10\:50 +0530")

"Pandita, Vikram" <vikram.pandita@ti.com> writes:

>>Steve Sakoman <sakoman@gmail.com> writes:
>>
>>> On Wed, Dec 23, 2009 at 1:06 PM, Robert Nelson <robertcnelson@gmail.com> wrote:
>>>> On Wed, Dec 23, 2009 at 2:59 PM, Steve Sakoman <sakoman@gmail.com> wrote:
>>>>> I'm seeing some strange behavior with my console serial port with 2.6.32.
>>>>>
> <snip>
>>This will also have obvious and serious PM implications for non
>>serial-console devices connected to UARTs (IrDA, bluetooth, modems,
>>etc.)
>
> OMAP uarts for BT etc use h/w flow control, which is another way of
> waking up omap before sending any chars and hence don’t loose data.

Good point.  However, I haven't personally tested (or heard) that it
actually works as would be expected.  Can you confirm working BT over
a UART with idle/unclocking enabled?

Kevin


> Console uses no flow control as you know.
>
>>
>>I've heard some ideas of muxing the UART into GPIO mode when idle and
>>having a bitbanging to get the first char so it is not lost, but
>>haven't seen any patches to do it.
>>
>>While it doesn't really solve your problem, I hope it at least helps
>>understand the reason for it.
>
> You could write a book on uart pm :)
>
>>
>>Kevin
>>
>>
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      reply	other threads:[~2010-01-07  0:25 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-12-23 20:59 serial port input corruption with 2.6.32? Steve Sakoman
2009-12-23 21:06 ` Robert Nelson
2009-12-23 21:22   ` Steve Sakoman
2010-01-06 23:26     ` Kevin Hilman
2010-01-06 23:40       ` Pandita, Vikram
2010-01-07  0:25         ` Kevin Hilman [this message]

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