From mboxrd@z Thu Jan  1 00:00:00 1970
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
Subject: Re: [PATCH] amba-pl011: simplify TX handling
Date: Wed, 18 Mar 2015 23:43:48 +0000
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To: Dave P Martin <Dave.Martin@arm.com>
Cc: Jakub =?utf-8?B?S2ljacWEc2tp?= <moorray3@wp.pl>, Jakub Kicinski <kubakici@wp.pl>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Karol Debogorski <k.debogorski@a2s.pl>, "linux-serial@vger.kernel.org" <linux-serial@vger.kernel.org>, Andre Przywara <Andre.Przywara@arm.com>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>
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On Wed, Mar 18, 2015 at 05:41:57PM +0000, Dave P Martin wrote:
>  * uart_wait_until_sent()'s timeout calculations aim to wait for
>    no longer than it takes the FIFO to drain.  However, this function
>    can get called when the serial_core xmit queue for the port is
>    very non-empty -- meaning that the FIFO continues to be topped
>    up for some time.  This can cause more data to be lost.

The code used to wait for the xmit queue to empty (up to closing_wait)
before shutting the port down, which defaulted to 30 seconds.  If the
xmit queue doesn't drain in 30 seconds, it probably never will.

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