From: Tony Lindgren <tony@atomide.com>
To: Russell King - ARM Linux <linux@armlinux.org.uk>
Cc: Aaro Koskinen <aaro.koskinen@iki.fi>,
Peter Ujfalusi <peter.ujfalusi@ti.com>,
vkoul@kernel.org, dan.j.williams@intel.com,
dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-omap@vger.kernel.org
Subject: Re: [PATCH] dmaengine: ti: omap-dma: Configure LCH_TYPE for OMAP1
Date: Sat, 24 Nov 2018 17:11:31 -0800 [thread overview]
Message-ID: <20181125011131.GK53235@atomide.com> (raw)
In-Reply-To: <20181125010717.GJ53235@atomide.com>
* Tony Lindgren <tony@atomide.com> [181125 01:07]:
> * Russell King - ARM Linux <linux@armlinux.org.uk> [181124 20:10]:
> > On Fri, Nov 23, 2018 at 08:52:15PM +0200, Aaro Koskinen wrote:
> > > Hi,
> > >
> > > On Fri, Nov 23, 2018 at 02:35:04PM +0200, Peter Ujfalusi wrote:
> > > > On 22/11/2018 17.12, Russell King - ARM Linux wrote:
> > > > > I'm also not sure about this:
> > > > >
> > > > > if (cpu_is_omap15xx())
> > > > > end++;
> > > > >
> > > > > in dma_dest_len() - is that missing from the omap-dma driver? It looks
> > > > > like a work-around for some problem on OMAP15xx, but I can't make sense
> > > > > about why it's in the UDC driver rather than the legacy DMA driver.
> > > >
> > > > afaik no other legacy drivers were doing similar thing, this must be
> > > > something which is needed for the omap_udc driver to fix up something?
> > >
> > > Here's the patch that added it: https://marc.info/?l=linux-omap&m=119634396324221&w=2
> > >
> > > "Make DMA-OUT behave on the 1510 ... the 1510 CPC register was just
> > > off-by-one with respect to the 1611 CDAC"
> >
> > ... which suggests that's a problem with the CPC register itself, and
> > we should fix that in the DMAengine driver rather than the USB gadget
> > driver.
> >
> > Tony, any input on this?
>
> Yeah that sounds like some hardware work-around for 15xx as described
> in the DMA_DEST_LAST macro reading CSAC on 15xx instead of CDAC. Seems
> like it should be done in the dmaengine driver.. My guess is that other
> dma users never needed to read CSAC register?
And it looks like for 15xx we have CPC and CSAC both at offset 0x18 in
arch/arm/mach-omap1/dma.c, seems like the dma driver is missing handling
for the CPC register that's there only for 15xx.
Regards,
Tony
next prev parent reply other threads:[~2018-11-25 1:11 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
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 [this message]
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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