From: Russell King - ARM Linux <linux@armlinux.org.uk>
To: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: Peter Ujfalusi <peter.ujfalusi@ti.com>,
vkoul@kernel.org, dan.j.williams@intel.com,
dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org,
tony@atomide.com, linux-omap@vger.kernel.org
Subject: Re: [PATCH] dmaengine: ti: omap-dma: Configure LCH_TYPE for OMAP1
Date: Fri, 23 Nov 2018 00:25:49 +0000 [thread overview]
Message-ID: <20181123002549.GO6920@n2100.armlinux.org.uk> (raw)
In-Reply-To: <20181122222426.GC11423@darkstar.musicnaut.iki.fi>
On Fri, Nov 23, 2018 at 12:24:26AM +0200, Aaro Koskinen wrote:
> Hi,
>
> On Thu, Nov 22, 2018 at 03:12:36PM +0000, Russell King - ARM Linux wrote:
> > On Thu, Nov 22, 2018 at 10:29:48AM +0000, Russell King - ARM Linux wrote:
> > > On Tue, Nov 20, 2018 at 11:04:06PM +0200, Aaro Koskinen wrote:
> > > > I had switched to PIO mode in 2015 since the WARNs about legacy DMA
> > > > API were too annoying and flooding the console. And now that I tried
> > > > using DMA again with g_ether, it doesn't work anymore. The device get's
> > > > recognized on host side, but no traffic goes through. Switching back to
> > > > PIO makes it to work again.
> > >
> > > A solution to that would be to do what the warning message says, and
> > > update the driver to the DMAengine API.
>
> Fully agreed, but I was busy debugging other more serious issues, and
> just wanted to get a reliable ssh or USB serial access to the device
> without any extra noise, so switching to PIO using a module parameter
> is probably what most users do in such situations.
>
> > Here's a partial conversion (not even build tested) - it only supports
> > OUT transfers with dmaengine at the moment.
>
> Thanks, I'll take a closer look and try to do some testing hopefully
> during the weekend.
The patch was more for Peter to take a peek at - there's definitely
some bits missing in the dmaengine driver (like the write to the
LCH_CTRL register) that would need to be fixed somehow.
However, it's worth noting that there is exactly one user of
omap_set_dma_channel_mode(), which is omap-udc, which means any DMA
channel made use of by omap-udc will have the LCH_CTRL register
modified to LCH_P, and it will remain that way even if someone else
subsequently makes use of the same channel. That's rather suspicious
to me... maybe we can just initialise all LCH_CTRL registers to LCH_P
in the dmaengine driver in that case! If not, then there's a bug
right there.
--
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
According to speedtest.net: 11.9Mbps down 500kbps up
next prev parent reply other threads:[~2018-11-23 0:26 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-19 10:40 [PATCH] dmaengine: ti: omap-dma: Configure LCH_TYPE for OMAP1 Peter Ujfalusi
2018-11-19 18:46 ` Aaro Koskinen
2018-11-20 7:28 ` Peter Ujfalusi
2018-11-20 21:04 ` Aaro Koskinen
2018-11-22 8:31 ` Peter Ujfalusi
2018-11-22 22:01 ` Aaro Koskinen
2018-11-23 11:45 ` Peter Ujfalusi
2018-11-24 0:17 ` Aaro Koskinen
2018-11-24 17:48 ` Russell King - ARM Linux
2018-11-24 19:06 ` Aaro Koskinen
2018-11-24 19:29 ` Russell King - ARM Linux
2018-11-22 10:29 ` Russell King - ARM Linux
2018-11-22 15:12 ` Russell King - ARM Linux
2018-11-22 22:24 ` Aaro Koskinen
2018-11-23 0:25 ` Russell King - ARM Linux [this message]
2018-11-23 1:23 ` Aaro Koskinen
2018-11-23 11:54 ` Peter Ujfalusi
2018-11-23 12:35 ` Peter Ujfalusi
2018-11-23 15:43 ` Russell King - ARM Linux
2018-11-23 16:16 ` Russell King - ARM Linux
2018-11-23 23:27 ` Russell King - ARM Linux
2018-11-23 18:52 ` Aaro Koskinen
2018-11-24 20:09 ` Russell King - ARM Linux
2018-11-25 1:07 ` Tony Lindgren
2018-11-25 1:11 ` Tony Lindgren
2018-11-25 11:11 ` Russell King - ARM Linux
2018-11-25 11:57 ` Russell King - ARM Linux
2018-11-25 16:58 ` Aaro Koskinen
2018-11-25 17:14 ` Tony Lindgren
2018-12-17 23:47 ` Aaro Koskinen
2018-12-18 15:55 ` Tony Lindgren
2018-12-17 19:16 ` Aaro Koskinen
2018-12-18 10:11 ` Peter Ujfalusi
2018-11-23 11:49 ` Peter Ujfalusi
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