From: Gerhard Sittig <gsi@denx.de>
To: Lars-Peter Clausen <lars@metafoo.de>
Cc: Arnd Bergmann <arnd@arndb.de>, Vinod Koul <vinod.koul@intel.com>,
devicetree-discuss@lists.ozlabs.org,
Alexander Popov <a13xp0p0v88@gmail.com>,
Dan Williams <djbw@fb.com>, Anatolij Gustschin <agust@denx.de>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH RFC 1/8] powerpc: mpc512x_dma: add support for data transfers between memory and i/o memory
Date: Sun, 14 Jul 2013 13:07:08 +0200 [thread overview]
Message-ID: <20130714110708.GC7080@book.gsilab.sittig.org> (raw)
In-Reply-To: <51E277E5.8050305@metafoo.de>
On Sun, Jul 14, 2013 at 12:05 +0200, Lars-Peter Clausen wrote:
>
> On 07/12/2013 05:26 PM, Gerhard Sittig wrote:
> [...]
> ]
> > + if (mchan->tcd_nunits)
> > + tcd->nbytes = mchan->tcd_nunits * 4;
> > + else
> > + tcd->nbytes = 64;
>
> Just wondering where does the magic 64 come from?
"Inherited" from Alexander's submission. By coincidence the SDHC
client happened to work with this constraint, as did Alexander's
LPB test suite. I'm not aware of other DMA clients as of now
(except for the memory transfer, which runs a different prep
routine).
It looks like there is more potential for generalization and auto
adapting to user input (adjusting configurable inner-loop
parameters to exactly fullfill the overall job from the user's
spec yet meet the chunking constraints of the hardware).
virtually yours
Gerhard Sittig
--
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr. 5, D-82194 Groebenzell, Germany
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next prev parent reply other threads:[~2013-07-14 11:07 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-12 15:26 [PATCH RFC 0/8] MPC512x DMA slave s/g support, OF DMA lookup Gerhard Sittig
2013-07-12 15:26 ` [PATCH RFC 1/8] powerpc: mpc512x_dma: add support for data transfers between memory and i/o memory Gerhard Sittig
2013-07-14 10:05 ` Lars-Peter Clausen
2013-07-14 11:07 ` Gerhard Sittig [this message]
2013-07-12 15:26 ` [PATCH RFC 2/8] dma: mpc512x: fix start condition in execute() Gerhard Sittig
2013-07-12 15:26 ` [PATCH RFC 3/8] dma: mpc512x: support 'terminate all' control request Gerhard Sittig
2013-07-12 15:26 ` [PATCH RFC 4/8] dts: mpc512x: prepare for preprocessor support Gerhard Sittig
2013-07-12 15:26 ` [PATCH RFC 5/8] dma: mpc512x: use symbolic specifiers for DMA channels Gerhard Sittig
2013-07-13 7:17 ` Arnd Bergmann
2013-07-13 14:14 ` Gerhard Sittig
2013-07-14 8:50 ` Arnd Bergmann
2013-07-14 9:53 ` Lars-Peter Clausen
2013-07-14 11:02 ` Gerhard Sittig
2013-07-12 15:26 ` [PATCH RFC 6/8] dma: of: Add common xlate function for matching by channel id Gerhard Sittig
2013-07-12 15:26 ` [PATCH RFC 7/8] dma: mpc512x: register for device tree channel lookup Gerhard Sittig
2013-07-12 15:26 ` [PATCH RFC 8/8] HACK mmc: mxcmmc: enable clocks for the MPC512x Gerhard Sittig
2013-07-12 16:45 ` [PATCH RFC 0/8] MPC512x DMA slave s/g support, OF DMA lookup Lars-Peter Clausen
2013-07-14 12:01 ` [PATCH RFC v2 0/5] " Gerhard Sittig
2013-07-14 12:01 ` [PATCH RFC v2 1/5] dma: mpc512x: re-order mpc8308 specific instructions Gerhard Sittig
2013-08-12 13:38 ` Alexander Popov
2013-07-14 12:01 ` [PATCH RFC v2 2/5] dma: mpc512x: add support for peripheral transfers Gerhard Sittig
2013-07-16 10:37 ` Lars-Peter Clausen
2013-07-17 10:42 ` Gerhard Sittig
2013-07-31 7:46 ` Alexander Popov
2013-08-12 13:37 ` Alexander Popov
2013-07-14 12:01 ` [PATCH RFC v2 3/5] dma: of: Add common xlate function for matching by channel id Gerhard Sittig
2013-10-03 14:05 ` Alexander Popov
2013-07-14 12:02 ` [PATCH RFC v2 4/5] dma: mpc512x: register for device tree channel lookup Gerhard Sittig
2013-10-03 14:06 ` Alexander Popov
2013-07-14 12:02 ` [PATCH RFC v2 5/5] HACK mmc: mxcmmc: enable clocks for the MPC512x Gerhard Sittig
2013-10-03 14:06 ` Alexander Popov
2013-07-16 9:27 ` [PATCH RFC v2 0/5] MPC512x DMA slave s/g support, OF DMA lookup Alexander Popov
2013-10-03 14:00 ` Alexander Popov
2013-10-06 10:01 ` Gerhard Sittig
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