On Tue, Dec 30, 2014 at 8:28 PM, Rob Herring [off-list ref] wrote:

From: Rob Herring <robh@kernel.org>

Disable the Versatile PCI DT node when no PCI backplane is detected. This
will prevent the Versatile PCI driver from probing when PCI is not
populated.

Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Russell King <redacted>
Cc: Linus Walleij <redacted>

(...)

+       /* Check if PCI backplane is detected */
+       val = __raw_readl(base + VERSATILE_SYS_PCICTL_OFFSET);

I think this kind of random syscon register access should be handled
using the mfd/syscon.c hub and looked up in some way to be used
by the driver.

I'm thinking along the pattern of adding code in drivers/*
by the pattern of e.g.
drivers/video/fbdev/amba-clcd-versatile.c
i.e. an add-on that gets compiled-in only for those platform
but still married to the main driver.

Yours,
Linus Walleij