Hi Stephen,
On 14/06/23 12:51 am, Stephen Boyd wrote:
Quoting Harshit Mogalapalli (2023-06-13 10:11:43)
Hi Maxime,
On 05/05/23 4:56 pm, Maxime Ripard wrote:
The Spreadtrum composite clocks implements a mux with a set_parent
hook, but doesn't provide a determine_rate implementation.
This is a bit odd, since set_parent() is there to, as its name implies,
change the parent of a clock. However, the most likely candidate to
trigger that parent change is a call to clk_set_rate(), with
determine_rate() figuring out which parent is the best suited for a
given rate.
The other trigger would be a call to clk_set_parent(), but it's far less
used, and it doesn't look like there's any obvious user for that clock.
So, the set_parent hook is effectively unused, possibly because of an
oversight. However, it could also be an explicit decision by the
original author to avoid any reparenting but through an explicit call to
clk_set_parent().
The driver does implement round_rate() though, which means that we can
change the rate of the clock, but we will never get to change the
parent.
However, It's hard to tell whether it's been done on purpose or not.
Since we'll start mandating a determine_rate() implementation, let's
convert the round_rate() implementation to a determine_rate(), which
will also make the current behavior explicit. And if it was an
oversight, the clock behaviour can be adjusted later on.
Cc: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Cc: Chunyan Zhang <zhang.lyra@xxxxxxxxx>
Cc: Orson Zhai <orsonzhai@xxxxxxxxx>
Acked-by: Chunyan Zhang <zhang.lyra@xxxxxxxxx>
Signed-off-by: Maxime Ripard <maxime@xxxxxxxxxx>
---
drivers/clk/sprd/composite.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/drivers/clk/sprd/composite.c b/drivers/clk/sprd/composite.c
index ebb644820b1e..d3a852720c07 100644
--- a/drivers/clk/sprd/composite.c
+++ b/drivers/clk/sprd/composite.c
@@ -9,13 +9,19 @@
#include "composite.h"
-static long sprd_comp_round_rate(struct clk_hw *hw, unsigned long rate,
- unsigned long *parent_rate)
+static int sprd_comp_determine_rate(struct clk_hw *hw,
+ struct clk_rate_request *req)
{
struct sprd_comp *cc = hw_to_sprd_comp(hw);
+ unsigned long rate;
- return sprd_div_helper_round_rate(&cc->common, &cc->div,
- rate, parent_rate);
+ rate = sprd_div_helper_round_rate(&cc->common, &cc->div,
+ req->rate, &req->best_parent_rate);
+ if (rate < 0)
+ return rate;
As rate is unsigned long, it can never be less than zero, so the above
if condition is never true. Smatch detected this.
Also if we just change the type of rate from unsigned long to long, will
the return type of the function "sprd_comp_determine_rate" being int is
correct?
The return type of the determine_rate clk_op is int. We can't change
that. Are you asking if long will be converted properly to an int when
it is signed?
Yes, thanks for clarifying.
Thanks,
Harshit
I see that sprd_div_helper_round_rate() calls divider_round_rate() which
calls divider_round_rate_parent() which calls divider_determine_rate(),
so we might as well change everything here to call
divider_determine_rate() directly. That significantly cleans things up.
----8<----
diff --git a/drivers/clk/sprd/composite.c b/drivers/clk/sprd/composite.c
index d3a852720c07..ad6b6383e21f 100644
--- a/drivers/clk/sprd/composite.c
+++ b/drivers/clk/sprd/composite.c
@@ -13,15 +13,8 @@ static int sprd_comp_determine_rate(struct clk_hw *hw,
struct clk_rate_request *req)
{
struct sprd_comp *cc = hw_to_sprd_comp(hw);
- unsigned long rate;
- rate = sprd_div_helper_round_rate(&cc->common, &cc->div,
- req->rate, &req->best_parent_rate);
- if (rate < 0)
- return rate;
-
- req->rate = rate;
- return 0;
+ return divider_determine_rate(hw, req, NULL, cc->div.width, 0);
}
static unsigned long sprd_comp_recalc_rate(struct clk_hw *hw,
diff --git a/drivers/clk/sprd/div.c b/drivers/clk/sprd/div.c
index 7621a1d1ab9c..c7261630cab4 100644
--- a/drivers/clk/sprd/div.c
+++ b/drivers/clk/sprd/div.c
@@ -9,23 +9,13 @@
#include "div.h"
-long sprd_div_helper_round_rate(struct sprd_clk_common *common,
- const struct sprd_div_internal *div,
- unsigned long rate,
- unsigned long *parent_rate)
-{
- return divider_round_rate(&common->hw, rate, parent_rate,
- NULL, div->width, 0);
-}
-EXPORT_SYMBOL_GPL(sprd_div_helper_round_rate);
-
static long sprd_div_round_rate(struct clk_hw *hw, unsigned long rate,
unsigned long *parent_rate)
{
struct sprd_div *cd = hw_to_sprd_div(hw);
- return sprd_div_helper_round_rate(&cd->common, &cd->div,
- rate, parent_rate);
+ return divider_round_rate(&cd->common.hw, rate, parent_rate, NULL,
+ cd->div.width, 0);
}
unsigned long sprd_div_helper_recalc_rate(struct sprd_clk_common *common,
diff --git a/drivers/clk/sprd/div.h b/drivers/clk/sprd/div.h
index 6acfe6b179fc..f5d614b3dcf1 100644
--- a/drivers/clk/sprd/div.h
+++ b/drivers/clk/sprd/div.h
@@ -64,11 +64,6 @@ static inline struct sprd_div *hw_to_sprd_div(const struct clk_hw *hw)
return container_of(common, struct sprd_div, common);
}
-long sprd_div_helper_round_rate(struct sprd_clk_common *common,
- const struct sprd_div_internal *div,
- unsigned long rate,
- unsigned long *parent_rate);
-
unsigned long sprd_div_helper_recalc_rate(struct sprd_clk_common *common,
const struct sprd_div_internal *div,
unsigned long parent_rate);
