dmaengine: ste_dma40: add software lli support
authorFabio Baltieri <fabio.baltieri@linaro.org>
Tue, 18 Dec 2012 11:25:14 +0000 (12:25 +0100)
committerFabio Baltieri <fabio.baltieri@linaro.org>
Mon, 14 Jan 2013 09:51:08 +0000 (10:51 +0100)
commit7407048bec896268b50e3c43c1d012a4764dc210
tree259a92df30b4c9e08cc0c2270bc997fa212225cb
parent7ce529efbcf6fdcb1854e4634adf7f6a18216e81
dmaengine: ste_dma40: add software lli support

This patch add support to manage LLI by SW for select phy channels.

There is a HW issue in certain controllers due to which on certain
occassions HW LLI cannot be used on some physical channels.  To avoid
the HW issue on a specific phy channel, the phy channel number can be
added to the list of soft_lli_channels and there after all the transfers
on that channel will use software LLI, for peripheral to memory
transfers.

SoftLLI introduces relink overhead, that could impact performace for
certain use cases.

This is based on a previous patch of Narayanan Gopalakrishnan.

Cc: Shreshtha Kumar Sahu <shreshthakumar.sahu@stericsson.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Fabio Baltieri <fabio.baltieri@linaro.org>
drivers/dma/ste_dma40.c
include/linux/platform_data/dma-ste-dma40.h