[alsa-devel] [RFC PATCH 03/11] dma: amba-pl08x: Add support for different offset of CONFIG register

[Russell King - ARM Linux]

On Sun, Jun 16, 2013 at 10:54:10PM +0200, Tomasz Figa wrote:
> Some variants of PL08x (namely PL080S, found in Samsung S3C64xx SoCs)
> have CONFIG register at different offset. This patch makes the driver
> use offset from vendor data struct.

I'd suggest doing this a different way.  Instead of having to pass around
two pointers everywhere in order to access this register, add to
struct pl08x_phy_chan a void __iomem *reg_config; member, and initialize
that to base + vd->config_offset.  Then use ch->reg_cfg instead of
ch->base + PL080_CH_CONFIG.

This has the benefit that you won't have to modify a whole load of
functions to pass another argument, which costs not only an additional
register, but also storage to keep it around.