OMAP2+ clock: revise omap2_clk_{disable,enable}()

Simplify the code in the omap2_clk_disable() and omap2_clk_enable()
functions, reducing levels of indentation.  This makes the code easier
to read.  Add some additional debugging pr_debug()s here also to help
others understand what is going on.

Revise the omap2_clk_disable() logic so that it now attempts to
disable the clock's clockdomain before recursing up the clock tree.
Simultaneously, ensure that omap2_clk_enable() is called on parent
clocks first, before enabling the clockdomain.  This ensures that a
parent clock's clockdomain is enabled before the child clock's
clockdomain.  These sequences should be the inverse of each other.

Revise the omap2_clk_enable() logic so that it now cleans up after
itself upon encountering an error.  Previously, an error enabling a
parent clock could have resulted in inconsistent usecounts on the
enclosing clockdomain.

Remove the trivial _omap2_clk_disable() and _omap2_clk_enable() static
functions, and replace it with the clkops calls that they were
executing.

For all this to work, the clockdomain omap2_clkdm_clk_enable() and
omap2_clkdm_clk_disable() code must not return an error on clockdomains
without CLKSTCTRL registers; so modify those functions to simply return 0
in that case.

While here, add some basic kerneldoc documentation on both functions,
and get rid of some old non-CodingStyle-compliant comments that have
existed since the dawn of time (at least, the OMAP clock framework's
time).

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Richard Woodruff <r-woodruff2@ti.com>
Cc: Rajendra Nayak <rnayak@ti.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/arch/arm/mach-omap2/clockdomain.c b/arch/arm/mach-omap2/clockdomain.c
index b26d30a14303..b87ad66f083e 100644
--- a/arch/arm/mach-omap2/clockdomain.c
+++ b/arch/arm/mach-omap2/clockdomain.c
@@ -978,7 +978,7 @@ int omap2_clkdm_clk_enable(struct clockdomain *clkdm, struct clk *clk)
          * downstream clocks for debugging purposes?
          */
 
-        if (!clkdm || !clk || !clkdm->clkstctrl_reg)
+        if (!clkdm || !clk)
                 return -EINVAL;
 
         if (atomic_inc_return(&clkdm->usecount) > 1)
@@ -989,6 +989,9 @@ int omap2_clkdm_clk_enable(struct clockdomain *clkdm, struct clk *clk)
         pr_debug("clockdomain: clkdm %s: clk %s now enabled\n", clkdm->name,
                  clk->name);
 
+        if (!clkdm->clkstctrl_reg)
+                return 0;
+
         v = omap2_clkdm_clktrctrl_read(clkdm);
 
         if ((cpu_is_omap34xx() && v == OMAP34XX_CLKSTCTRL_ENABLE_AUTO) ||
@@ -1030,7 +1033,7 @@ int omap2_clkdm_clk_disable(struct clockdomain *clkdm, struct clk *clk)
          * downstream clocks for debugging purposes?
          */
 
-        if (!clkdm || !clk || !clkdm->clkstctrl_reg)
+        if (!clkdm || !clk)
                 return -EINVAL;
 
 #ifdef DEBUG
@@ -1048,6 +1051,9 @@ int omap2_clkdm_clk_disable(struct clockdomain *clkdm, struct clk *clk)
         pr_debug("clockdomain: clkdm %s: clk %s now disabled\n", clkdm->name,
                  clk->name);
 
+        if (!clkdm->clkstctrl_reg)
+                return 0;
+
         v = omap2_clkdm_clktrctrl_read(clkdm);
 
         if ((cpu_is_omap34xx() && v == OMAP34XX_CLKSTCTRL_ENABLE_AUTO) ||