dma: apbh: Add special circular mode for LCD
authorMarek Vasut <marex@denx.de>
Tue, 30 Jul 2013 21:37:51 +0000 (23:37 +0200)
committerAnatolij Gustschin <agust@denx.de>
Fri, 9 Aug 2013 19:48:34 +0000 (21:48 +0200)
commit69f7345c95011cdc46d0ecf5e62c16d711e2eb2a
treee7cb55607c9ae2354a87ac8ae1f015df0464c650
parenta78dac79ede7fbb4c9e816abc879655540c3f076
dma: apbh: Add special circular mode for LCD

Add special function that executes a specially crafted circular
DMA descriptor. The function doesn't wait for the descriptor to
finish the transfer, since the descritor never finishes. This is
useful when operating a SmartLCD through the LCDIF interface, as
the LCDIF does not give us any means to have continuous refresh
of the SmartLCD. Instead, the RUN bit in the LCDIF CTRL register
must be triggered manually. This can be worked around by starting
an DMA transfer which continuously sets the RUN bit. This function
allows starting exactly such transfer.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Anatolij Gustschin <agust@denx.de>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Otavio Salvador <otavio@ossystems.com.br>
Cc: Stefano Babic <sbabic@denx.de>
arch/arm/include/asm/imx-common/dma.h
drivers/dma/apbh_dma.c