From: u.kleine-koenig@pengutronix.de (Uwe Kleine-König)
To: linux-arm-kernel@lists.infradead.org
Subject: DCD interrupt for i.MX25 UART
Date: Mon, 4 Apr 2016 22:49:11 +0200 [thread overview]
Message-ID: <20160404204911.GA5384@pengutronix.de> (raw)
In-Reply-To: <20160329131443.09e46ad6@ipc1.ka-ro>
Hallo Lothar,
On Tue, Mar 29, 2016 at 01:14:43PM +0200, Lothar Wa?mann wrote:
> On Wed, 23 Mar 2016 16:36:38 +0100 Uwe Kleine-K?nig wrote:
> > Hello,
> >
> > I have a problem with an UART on an i.MX25 based machine. I implemented
> > DCD (and other handshake lines) irq handling[1].
> >
> > Now a user of this patch noticed that DCD handling (at least) is broken.
> > The problem is that the USR2_DCDDELT bit doesn't clear:
> >
> > root at hostname:~ memtool md 0x43f90080+0x34
> > 43f90080: 00000000 00004021 0000078c 00004002 ....!@....... at ..
> > 43f90090: 00000b41 00002040 00005268 0000002b A...@ ..hR..+...
> > 43f900a0: 00000000 000000bf 00002e62 00000008 ........b.......
> > 43f900b0: 0000251c .%..
> >
> > root at hostname:~ memtool mw 0x43f90098 0x0x40
> ^^^^^^
> This looks rather fishy.
Probably a cut-and-paste problem. I tried this several times with
various values, the bit doesn't clear.
> > root at hostname:~ memtool md 0x43f90080+0x34
> > 43f90080: 00000000 00004021 0000078c 00004002 ....!@....... at ..
> > 43f90090: 00000b41 00002040 00005268 0000002b A...@ ..hR..+...
> > 43f900a0: 00000000 000000bf 00002e62 00000008 ........b.......
> > 43f900b0: 0000251c .%..
> >
> > In fact even writing 0xffff doesn't change the register, where I would expect
> > that the DCDDELT bit (0x40) disappears. I'm sure there is nothing toggling this
> > line.
> >
> Are you sure the clock is enabled when doing your manual tests?
I guess they are. For sure the same thing happens with the driver active
and the device open. And the symptoms are the same: If the DCDDELTA irq
is enabled and active the machine is stuck until the irq upper layers
disable the respective irq.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-K?nig |
Industrial Linux Solutions | http://www.pengutronix.de/ |
prev parent reply other threads:[~2016-04-04 20:49 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-23 15:36 DCD interrupt for i.MX25 UART Uwe Kleine-König
2016-03-29 11:14 ` Lothar Waßmann
2016-04-04 20:49 ` Uwe Kleine-König [this message]
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