diff mbox series

[v3,63/65] ASoC: tlv320aic32x4: pll: Switch to determine_rate

Message ID 20221018-clk-range-checks-fixes-v3-63-9a1358472d52@cerno.tech
State Handled Elsewhere
Headers show
Series clk: Make determine_rate mandatory for muxes | expand

Commit Message

maxime@cerno.tech April 4, 2023, 10:11 a.m. UTC 
The tlv320aic32x4 PLL 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.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
---
 sound/soc/codecs/tlv320aic32x4-clk.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

Comments

Mark Brown April 5, 2023, 3:09 p.m. UTC | #1 
On Tue, Apr 04, 2023 at 12:11:53PM +0200, Maxime Ripard wrote:

> 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.

Similar comments to the other patch, I'm pretty sure this is just
surprising design on the part of the clock API and we should just allow
reparenting.
diff mbox series

Patch

diff --git a/sound/soc/codecs/tlv320aic32x4-clk.c b/sound/soc/codecs/tlv320aic32x4-clk.c
index 65b72373cb95..d8b8ea3eaa12 100644
--- a/sound/soc/codecs/tlv320aic32x4-clk.c
+++ b/sound/soc/codecs/tlv320aic32x4-clk.c
@@ -205,18 +205,23 @@  static unsigned long clk_aic32x4_pll_recalc_rate(struct clk_hw *hw,
 	return clk_aic32x4_pll_calc_rate(&settings, parent_rate);
 }
 
-static long clk_aic32x4_pll_round_rate(struct clk_hw *hw,
-			unsigned long rate,
-			unsigned long *parent_rate)
+static int clk_aic32x4_pll_determine_rate(struct clk_hw *hw,
+					  struct clk_rate_request *req)
 {
 	struct clk_aic32x4_pll_muldiv settings;
+	unsigned long rate;
 	int ret;
 
-	ret = clk_aic32x4_pll_calc_muldiv(&settings, rate, *parent_rate);
+	ret = clk_aic32x4_pll_calc_muldiv(&settings, req->rate, req->best_parent_rate);
 	if (ret < 0)
-		return 0;
+		return -EINVAL;
 
-	return clk_aic32x4_pll_calc_rate(&settings, *parent_rate);
+	rate = clk_aic32x4_pll_calc_rate(&settings, req->best_parent_rate);
+	if (rate < 0)
+		return rate;
+
+	req->rate = rate;
+	return 0;
 }
 
 static int clk_aic32x4_pll_set_rate(struct clk_hw *hw,
@@ -267,7 +272,7 @@  static const struct clk_ops aic32x4_pll_ops = {
 	.unprepare = clk_aic32x4_pll_unprepare,
 	.is_prepared = clk_aic32x4_pll_is_prepared,
 	.recalc_rate = clk_aic32x4_pll_recalc_rate,
-	.round_rate = clk_aic32x4_pll_round_rate,
+	.determine_rate = clk_aic32x4_pll_determine_rate,
 	.set_rate = clk_aic32x4_pll_set_rate,
 	.set_parent = clk_aic32x4_pll_set_parent,
 	.get_parent = clk_aic32x4_pll_get_parent,