[PATCH v2 03/12] clk: Add a function to retrieve phase

Hi,

On Sun, Aug 31, 2014 at 12:15:50PM +0200, Hans de Goede wrote:

Hi,

On 08/30/2014 10:03 PM, Maxime Ripard wrote:

quoted

The current phase API doesn't look into the actual hardware to get the phase
value, but will rather get it from a variable only set by the set_phase
function.

This will cause issue when the client driver will never call the set_phase
function, where we can end up having a reported phase that will not match what
the hardware has been programmed to by the bootloader or what phase is
programmed out of reset.

Add a new get_phase function for the drivers to implement so that we can get
this value.

Signed-off-by: Maxime Ripard <redacted>
---
 drivers/clk/clk.c            | 17 ++++++++++++++---
 include/linux/clk-provider.h |  5 +++++
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index d87661af0c72..7dbceca694f1 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c

@@ -1797,8 +1797,8 @@ out:
  * clk_get_phase - return the phase shift of a clock signal
  * @clk: clock signal source
  *
- * Returns the phase shift of a clock node in degrees, otherwise returns
- * -EERROR.
+ * Returns the phase shift of a clock node in degrees. Any negative
+ * values are errors.
  */
 int clk_get_phase(struct clk *clk)
 {

@@ -1808,7 +1808,18 @@ int clk_get_phase(struct clk *clk)
 		goto out;
 
 	clk_prepare_lock();
-	ret = clk->phase;
+
+	if (clk->phase) {
+		ret = clk->phase;
+		goto out_unlock;
+	}

0 is a valid phase, so this will cause the phase to
be read from the hardware each time if the phase is 0.

Perhaps make clk->phase signed (if it is not already), init it
to -1, and check for it not being -1 ?

Yeah, I'm not really proud of this code either, but yours would expose
this -1 into debugfs, so I'm not sure it's really better :) 

(with -1 being a valid phase too)

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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