From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Peter Hurley <peter@hurleysoftware.com>,
John Ogness <john.ogness@linutronix.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Tony Lindgren <tony@atomide.com>,
nsekhar@ti.com, linux-kernel@vger.kernel.org,
linux-serial@vger.kernel.org, linux-omap@vger.kernel.org
Subject: Re: [PATCH] tty: serial: 8250_omap: do not defer termios changes
Date: Mon, 11 Apr 2016 20:31:23 +0200 [thread overview]
Message-ID: <570BED7B.9080803@linutronix.de> (raw)
In-Reply-To: <570BE48F.60801@hurleysoftware.com>
On 04/11/2016 07:53 PM, Peter Hurley wrote:
> On 04/11/2016 01:18 AM, John Ogness wrote:
>> On 2016-04-05, Peter Hurley <peter@hurleysoftware.com> wrote:
>>> On 03/31/2016 01:41 AM, John Ogness wrote:
>>>> It has been observed that the TX-DMA can stall
>>>
>>> Does this happen on any other OMAP part besides am335x?
>>> I looked back over the LKML history of this and didn't see
>>> any other design implicated in this problem.
>>
>> I just ran the tests again using 4.6-rc2. I am able to reproduce the
>> dma-tx stall with am335x/edma and dra7/sdma.
>
> I thought we already established sdma was not to be used since
> the hardware does not actually support pausing without data loss.
This workaround was not invented for sdma but for edma (with am335x).
> http://www.spinics.net/lists/linux-serial/msg18503.html
This could be fixed. See
http://www.spinics.net/lists/linux-serial/msg18517.html
http://www.spinics.net/lists/linux-serial/msg18531.html
rmk was fine with it from what I read. So what is missing is just
refurbish the patch (update the comment according to rmk replay) and
then we could re-enable DMA again.
> So I'm wondering if we're carrying all this extra DMA complexity
> and workarounds for just am335x?
>
Sebastian
next prev parent reply other threads:[~2016-04-11 18:31 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-31 8:41 [PATCH] tty: serial: 8250_omap: do not defer termios changes John Ogness
2016-03-31 8:41 ` John Ogness
2016-03-31 10:51 ` John Ogness
2016-03-31 14:33 ` One Thousand Gnomes
2016-04-05 4:07 ` Peter Hurley
2016-04-11 8:18 ` John Ogness
2016-04-11 17:53 ` Peter Hurley
2016-04-11 18:31 ` Sebastian Andrzej Siewior [this message]
2016-04-11 20:10 ` Peter Hurley
2016-04-12 17:03 ` Sebastian Andrzej Siewior
2016-04-12 18:42 ` Peter Hurley
2016-04-14 16:03 ` Peter Hurley
2016-04-12 23:20 ` 8250 dma issues ( was Re: [PATCH] tty: serial: 8250_omap: do not defer termios changes) Peter Hurley
2016-04-14 15:07 ` One Thousand Gnomes
2016-04-14 17:54 ` Peter Hurley
2016-04-13 0:00 ` omap uart + dma issues (Re: " Peter Hurley
2016-04-13 11:11 ` Sekhar Nori
2016-04-13 11:11 ` Sekhar Nori
2016-04-14 1:14 ` Peter Hurley
2016-05-03 12:00 ` [PATCH] tty: serial: 8250_omap: do not defer termios changes Vignesh R
2016-05-03 12:00 ` Vignesh R
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