[PATCH] clkdev: only fall through to clk_get_sys() if DT indicates no entry

Russell King rmk+kernel at arm.linux.org.uk
Sat Apr 26 08:49:52 PDT 2014

There are two failures which DT can return when looking up a phandle:
-ENOENT - when DT finds that the desired property/index is not present
-EINVAL - when DT finds that the desired property/index is present, but
 there is a problem parsing it.

We should only fall through to clk_get_sys() (the table driven clock
lookup) when DT indicates that there was no entry in the OF tables
for the clock.  Doing otherwise causes the clk API to always indicate
that there is no entry for this clock, which is not correct behaviour.

Cc: <stable at vger.kernel.org>
Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
Grant, Rob,

Please let me know ASAP if this gives you any cause for concern.  This
looks to me like a long standing bug which really needs fixing.  Part
of the motivation here is similar to Jean-Francois' patch to clkdev
which allows a DT specified clock which isn't get present to have
clk_get() and friends return -EPROBE_DEFER - again, something that I
think really should happen.  Jean-Francois hasn't been able to get
much traction for his patch, so let's start with fixing this bug first.

 drivers/clk/clkdev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clk/clkdev.c b/drivers/clk/clkdev.c
index 48f67218247c..4e65d0e10b05 100644
--- a/drivers/clk/clkdev.c
+++ b/drivers/clk/clkdev.c
@@ -165,7 +165,7 @@ struct clk *clk_get(struct device *dev, const char *con_id)
 	if (dev) {
 		clk = of_clk_get_by_name(dev->of_node, con_id);
-		if (!IS_ERR(clk))
+		if (!IS_ERR(clk) || PTR_ERR(clk) != -ENOENT)
 			return clk;

More information about the linux-arm-kernel mailing list