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From: "Remy Bohmer" <linux@bohmer.net>
To: michael <trimarchi@gandalf.sssup.it>
Cc: "Haavard Skinnemoen" <hskinnemoen@atmel.com>,
	fabio@gandalf.sssup.it, "Andrew Victor" <linux@maxim.org.za>,
	"Chip Coldwell" <coldwell@redhat.com>,
	"Marc Pignat" <marc.pignat@hevs.ch>,
	"David Brownell" <david-b@pacbell.net>,
	linux-kernel@vger.kernel.org,
	"Alan Cox" <alan@lxorguk.ukuu.org.uk>
Subject: Re: [PATCH -mm v4 6/9] atmel_serial: Split the interrupt handler
Date: Wed, 13 Feb 2008 21:13:37 +0100	[thread overview]
Message-ID: <3efb10970802131213y717d0c12t151ab9c61f4e9955@mail.gmail.com> (raw)
In-Reply-To: <47B2CF76.6050704@gandalf.sssup.it>

Hello All,

> All works now for me with preempt-rt. The problem is using hrtimer.
> I think that hrtimer are executed with interrupts disabled so, if
> this happen when I must receive a char, i have an overrun.

No, they share the same interrupt line...
So, while the timer interrupt handler is running, the serial handler
has to wait until the timer interrupt handler has finished.
Notice that the HRT interrupt handler is quite heavy and takes a long
time to complete.

And, as I already mentioned, related to the 1 byte FIFO and a
interrupt latency of about 85us (without HRT), it is logical that you
can get an overrun at the higher serial speeds... (>=115200bps)

> The only solution was the dma support to serial device.

Or, use flow control?


Kind Regards,

Remy

  reply	other threads:[~2008-02-13 20:13 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20080129224316.GA23155@gandalf.sssup.it>
2008-01-29 23:12 ` michael
2008-01-30  9:41   ` Haavard Skinnemoen
2008-01-30 10:21     ` Remy Bohmer
2008-01-30 10:34       ` Haavard Skinnemoen
2008-01-30 11:05         ` Remy Bohmer
2008-01-30 12:43           ` Haavard Skinnemoen
2008-01-30 15:25           ` michael
2008-01-30 10:29     ` michael
2008-01-30 12:36       ` Haavard Skinnemoen
2008-01-30 15:26         ` michael
2008-01-30 15:46           ` Haavard Skinnemoen
2008-01-31  1:53             ` michael
2008-01-31 15:07               ` Haavard Skinnemoen
2008-01-31 19:36                 ` Remy Bohmer
2008-02-04 12:39                   ` Haavard Skinnemoen
2008-02-04 19:44                     ` Remy Bohmer
2008-02-06 12:19                       ` michael
2008-02-06 19:41                         ` Remy Bohmer
2008-02-13 11:07                           ` michael
2008-02-13 20:13                             ` Remy Bohmer [this message]
2008-02-14  7:30                               ` michael
2008-02-04 19:01                 ` michael
2008-02-04 20:25                   ` Haavard Skinnemoen
2008-02-05 12:29                     ` michael
2008-02-06 12:30                       ` Haavard Skinnemoen
2008-02-06 13:41                         ` michael
2008-02-06 15:22                           ` Haavard Skinnemoen
2008-01-24 12:41 [PATCH -mm v4 0/9] atmel_serial cleanups and improvements Haavard Skinnemoen
2008-01-24 12:41 ` [PATCH -mm v4 1/9] MAINTAINERS: Add myself as maintainer of the atmel_serial driver Haavard Skinnemoen
2008-01-24 12:41   ` [PATCH -mm v4 2/9] atmel_serial: Clean up the code Haavard Skinnemoen
2008-01-24 12:41     ` [PATCH -mm v4 3/9] atmel_serial: Use cpu_relax() when busy-waiting Haavard Skinnemoen
2008-01-24 12:41       ` [PATCH -mm v4 4/9] atmel_serial: Use existing console options only if BRG is running Haavard Skinnemoen
2008-01-24 12:41         ` [PATCH -mm v4 5/9] atmel_serial: Fix bugs in probe() error path and remove() Haavard Skinnemoen
2008-01-24 12:41           ` [PATCH -mm v4 6/9] atmel_serial: Split the interrupt handler Haavard Skinnemoen

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