From: tomi.valkeinen@ti•com (Tomi Valkeinen)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 1/2] ARM: omapfb: add coherent dma memory support
Date: Thu, 9 Jan 2014 10:21:46 +0200 [thread overview]
Message-ID: <52CE5C1A.3070603@ti.com> (raw)
In-Reply-To: <79CD15C6BA57404B839C016229A409A83EDB11F5@DBDE04.ent.ti.com>
On 2014-01-09 07:06, Hiremath, Vaibhav wrote:
> I am seeing underflow issue on AM43x device if I use omapfb_vram argument.
> Did you see this on OMAP?
>
> I am using "omapfb_vram=10M at 0xA0000000", and I believe it is correct way of usage.
Hmm ok... The AM4x seems to have issues anyway, as we're seeing
underflows easily in other situations also.
Well, there's a small difference in the allocation. The normal dma alloc
uses dma_alloc_attrs() and passes DMA_ATTR_WRITE_COMBINE as a flag,
whereas allocating from the absolute address just uses the piece of
memory. I couldn't find how to set write-combine for the abs memory area.
Then again, that's for CPU caching, so I don't see why it would affect
DSS as such (but that's still something we should measure, cpu
read/write perf for normal and abs allocation).
The only thought I have is that somehow the reserved memory area is
missing some configuration that is done for the rest of the memory. But
that's purely a guess, this is totally out of my area of expertise...
Vaibhav, just to be sure, can you run both with normal dma_alloc and
with the reserve, and verify that the dispc register dumps are the same?
I don't see how they could be different, but just to be sure.
Tomi
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next prev parent reply other threads:[~2014-01-09 8:21 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-30 13:19 [PATCH 0/2] omapfb: option to use coherent dma mem Tomi Valkeinen
2013-12-30 13:19 ` [PATCH 1/2] ARM: omapfb: add coherent dma memory support Tomi Valkeinen
2014-01-05 14:16 ` Ivaylo Dimitrov
2014-01-07 23:59 ` Tony Lindgren
2014-01-08 14:13 ` Tomi Valkeinen
2014-01-09 5:06 ` Hiremath, Vaibhav
2014-01-09 7:34 ` Ivaylo Dimitrov
2014-01-09 8:08 ` Hiremath, Vaibhav
2014-01-09 8:27 ` Tomi Valkeinen
2014-01-09 8:31 ` Hiremath, Vaibhav
2014-01-11 13:28 ` Ivaylo Dimitrov
2014-01-22 21:08 ` Ivaylo Dimitrov
2014-01-24 8:47 ` Hiremath, Vaibhav
2014-01-24 10:35 ` Tomi Valkeinen
2014-01-09 8:21 ` Tomi Valkeinen [this message]
2014-01-09 8:31 ` Hiremath, Vaibhav
2014-01-09 13:02 ` Hiremath, Vaibhav
2013-12-30 13:19 ` [PATCH 2/2] omapfb: add support to reserve fb at specified phys address Tomi Valkeinen
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