On Mon, Jan 21, 2013 at 3:15 PM, Arnd Bergmann [off-list ref] wrote:

The __clk_get_name is used by drivers that provide their
own clocks, which have traditionally all been built-in.
The new imx drm driver however provides clocks but can
be built as a module, so we need to export __clk_get_name.

While this is only a staging driver, it's likely that
there will be others like it in the future.

Without this patch, building ARM allmodconfig results in:

ERROR: "__clk_get_name" [drivers/staging/imx-drm/ipu-v3/imx-ipu-v3.ko] undefined!

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Mike Turquette <redacted>

A fix from Niels de Vos has already been applied into clk-next:
https://patchwork.kernel.org/patch/1871981/