From: Alexander Stein <alexanders83@web.de>
To: linux-rpi-kernel@lists.infradead.org
Cc: "Stefan Wahren" <info@lategoodbye.de>,
"Noralf Trønnes" <noralf@tronnes.org>,
dmaengine@vger.kernel.org, vinod.koul@intel.com,
dan.j.williams@intel.com, jonathan@raspberrypi.org,
linux-kernel@vger.kernel.org
Subject: Re: Re: [PATCH] dmaengine: bcm2835: Add slave dma support
Date: Thu, 16 Apr 2015 21:06:49 +0200 [thread overview]
Message-ID: <8408334.G8cbCZ65GO@kongar> (raw)
In-Reply-To: <552EB54A.3060404@lategoodbye.de>
Hi Stefan,
On Wednesday 15 April 2015, 21:00:26 wrote Stefan Wahren:
> Am 15.04.2015 um 11:56 schrieb Noralf Trønnes:
> > Add slave transfer capability to BCM2835 dmaengine driver.
> > This patch is pulled from the bcm2708-dmaengine driver in the
> > Raspberry Pi repo. The work was done by Gellert Weisz.
> >
> > Tested with the bcm2835-mmc driver from the same repo.
>
> why not with the upstream kernel?
I also looked at slave dma support, especially for use in mmc. It turns our that bcm2835-mmc is written more or less completly new.
Mainline linux uses sdhci "framework" which internally uses the SDMA and/or ADMA (both internal, to SD/MMC controller, DMA units) which can be supported by an SDHCI compatible controller.
AFAIK the SD/MMC controller in bcm2835 lacks both that is why the driver only uses PIO. I dunno if external DMA usage can so easily be integrated into the sdhci, I have my doubts.
Best regards,
Alexander
next prev parent reply other threads:[~2015-04-16 19:07 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-15 9:56 [PATCH] dmaengine: bcm2835: Add slave dma support Noralf Trønnes
2015-04-15 14:37 ` Martin Sperl
2015-04-15 18:53 ` Noralf Trønnes
2015-04-16 6:30 ` Rogier Wolff
2015-04-16 17:28 ` Noralf Trønnes
2015-04-15 19:00 ` Stefan Wahren
2015-04-16 19:06 ` Alexander Stein [this message]
2015-04-16 22:03 ` Noralf Trønnes
2015-04-16 22:09 ` Noralf Trønnes
2015-04-17 17:08 ` Stefan Wahren
2015-04-17 17:19 ` Martin Sperl
2015-04-17 17:20 ` Noralf Trønnes
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