linux-kernel - [PATCH] clk: composite: Also consider .determine

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Message-Id: <20211015120559.3515645-1-martin.blumenstingl@googlemail.com>
Date:   Fri, 15 Oct 2021 14:05:59 +0200
From:   Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To:     sboyd@...nel.org
Cc:     heiko@...ech.de, knaerzche@...il.com,
        linux-arm-kernel@...ts.infradead.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-rockchip@...ts.infradead.org,
        martin.blumenstingl@...glemail.com
Subject: [PATCH] clk: composite: Also consider .determine_rate for rate + mux composites

Commit 69a00fb3d69706 ("clk: divider: Implement and wire up
.determine_rate by default") switches clk_divider_ops to implement
.determine_rate by default. This breaks composite clocks with multiple
parents because clk-composite.c does not use the special handling for
mux + divider combinations anymore (that was restricted to rate clocks
which only implement .round_rate, but not .determine_rate).

Alex reports:
  This breaks lot of clocks for Rockchip which intensively uses
  composites,  i.e. those clocks will always stay at the initial parent,
  which in some cases  is the XTAL clock and I strongly guess it is the
  same for other platforms,  which use composite clocks having more than
  one parent (e.g. mediatek, ti ...)

  Example (RK3399)
  clk_sdio is set (initialized) with XTAL (24 MHz) as parent in u-boot.
  It will always stay at this parent, even if the mmc driver sets a rate
  of  200 MHz (fails, as the nature of things), which should switch it
  to   any of its possible parent PLLs defined in
  mux_pll_src_cpll_gpll_npll_ppll_upll_24m_p (see clk-rk3399.c)  - which
  never happens.

Restore the original behavior by changing the priority of the conditions
inside clk-composite.c. Now the special rate + mux case (with rate_ops
having a .round_rate - which is still the case for the default
clk_divider_ops) is preferred over rate_ops which have .determine_rate
defined (and not further considering the mux).

Fixes: 69a00fb3d69706 ("clk: divider: Implement and wire up .determine_rate by default")
Reported-by: Alex Bee <knaerzche@...il.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
---
Re-sending this as inline patch instead of attaching it.

 drivers/clk/clk-composite.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/clk/clk-composite.c b/drivers/clk/clk-composite.c
index 0506046a5f4b..510a9965633b 100644
--- a/drivers/clk/clk-composite.c
+++ b/drivers/clk/clk-composite.c
@@ -58,11 +58,8 @@ static int clk_composite_determine_rate(struct clk_hw *hw,
 	long rate;
 	int i;

-	if (rate_hw && rate_ops && rate_ops->determine_rate) {
-		__clk_hw_set_clk(rate_hw, hw);
-		return rate_ops->determine_rate(rate_hw, req);
-	} else if (rate_hw && rate_ops && rate_ops->round_rate &&
-		   mux_hw && mux_ops && mux_ops->set_parent) {
+	if (rate_hw && rate_ops && rate_ops->round_rate &&
+	    mux_hw && mux_ops && mux_ops->set_parent) {
 		req->best_parent_hw = NULL;

 		if (clk_hw_get_flags(hw) & CLK_SET_RATE_NO_REPARENT) {
@@ -107,6 +104,9 @@ static int clk_composite_determine_rate(struct clk_hw *hw,

 		req->rate = best_rate;
 		return 0;
+	} else if (rate_hw && rate_ops && rate_ops->determine_rate) {
+		__clk_hw_set_clk(rate_hw, hw);
+		return rate_ops->determine_rate(rate_hw, req);
 	} else if (mux_hw && mux_ops && mux_ops->determine_rate) {
 		__clk_hw_set_clk(mux_hw, hw);
 		return mux_ops->determine_rate(mux_hw, req);
-- 
2.33.0