From: Anatolij Gustschin <agust@denx.de>
To: Sascha Hauer <s.hauer@pengutronix.de>
Cc: linux-mmc@vger.kernel.org, Chris Ball <cjb@laptop.org>,
Markus Pargmann <mpa@pengutronix.de>,
devicetree-discuss@lists.ozlabs.org
Subject: Re: [PATCH 4/5] mmc: mxcmmc: enable DMA support on mpc512x
Date: Thu, 14 Mar 2013 22:18:16 +0100 [thread overview]
Message-ID: <20130314221816.1e4c93c1@crub> (raw)
In-Reply-To: <20130314201139.GS1906@pengutronix.de>
On Thu, 14 Mar 2013 21:11:39 +0100
Sascha Hauer <s.hauer@pengutronix.de> wrote:
> On Thu, Mar 14, 2013 at 05:40:53PM +0100, Anatolij Gustschin wrote:
> > Add SDHC DMA channel description to the mpc512x device
> > tree to enable slave channel requesting in the mxcmmc
> > driver.
> >
> > mpc512x DMA engine doesn't support endianness conversion
> > when reading/writing data from peripheral's FIFO, so we
> > have to swap data buffers before each DMA write and after
> > each DMA read transfer manually.
> >
> > Since chained SDHC DMA transfers are not supported on
> > mpc512x, limit 'max_segs' tunable parameter to one and
> > initialise it to 64 only when running on i.MX platforms.
>
> They are also not supported on the older i.MX platforms. Shouldn't this
> be handled in the DMA driver?
This could be handled in the DMA driver, but up to now nobody
cared to extend the DMA driver so.
Anatolij
next prev parent reply other threads:[~2013-03-14 21:18 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-14 16:40 [PATCH 0/5] mmc: mxcmmc: add mpc512x support Anatolij Gustschin
2013-03-14 16:40 ` [PATCH 1/5] mmc: mxcmmc: add mpc512x SDHC support Anatolij Gustschin
2013-03-14 16:50 ` Arnd Bergmann
2013-03-14 18:13 ` Anatolij Gustschin
2013-03-14 20:05 ` Sascha Hauer
2013-03-14 22:52 ` Arnd Bergmann
2013-03-14 16:40 ` [PATCH 2/5] mmc: mxcmmc: use slot-gpio API for write-protect detection Anatolij Gustschin
2013-03-14 16:40 ` [PATCH 3/5] mmc: mxcmmc: constify mxcmci_devtype and fix build warning Anatolij Gustschin
2013-03-14 16:40 ` Anatolij Gustschin
2013-03-14 18:15 ` Anatolij Gustschin
2013-03-14 16:40 ` [PATCH 4/5] mmc: mxcmmc: enable DMA support on mpc512x Anatolij Gustschin
2013-03-14 20:11 ` Sascha Hauer
2013-03-14 21:18 ` Anatolij Gustschin [this message]
2013-03-14 16:40 ` [PATCH 5/5] mmc: mxcmmc: fix race conditions for host->req and host->data access Anatolij Gustschin
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