Re: [PATCH 4/5] mmc: mxcmmc: enable DMA support on mpc512x

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?

Sascha

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |