linux-kernel - [PATCH 1/5] clk: divider: read-only divider can propagate rate change

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Date:   Fri,  5 Jan 2018 18:09:55 +0100
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Stephen Boyd <sboyd@...eaurora.org>,
        Michael Turquette <mturquette@...libre.com>,
        linux-clk@...r.kernel.org
Cc:     Jerome Brunet <jbrunet@...libre.com>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, Vladimir Zapolskiy <vz@...ia.com>,
        Sylvain Lemieux <slemieux.tyco@...il.com>,
        Andy Gross <andy.gross@...aro.org>,
        David Brown <david.brown@...aro.org>
Subject: [PATCH 1/5] clk: divider: read-only divider can propagate rate change

When a divider clock has CLK_DIVIDER_READ_ONLY set, it means that the
register shall be left un-touched, but it does not mean the clock
should stop rate propagation if CLK_SET_RATE_PARENT is set

This is properly handled in qcom clk-regmap-divider but it was not in
the generic divider

Fixes: e6d5e7d90be9 ("clk-divider: Fix READ_ONLY when divider > 1")
Signed-off-by: Jerome Brunet <jbrunet@...libre.com>
---
 drivers/clk/clk-divider.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
index b49942b9fe50..a851d3e04c7f 100644
--- a/drivers/clk/clk-divider.c
+++ b/drivers/clk/clk-divider.c
@@ -348,6 +348,7 @@ static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
 				unsigned long *prate)
 {
 	struct clk_divider *divider = to_clk_divider(hw);
+	struct clk_hw *hw_parent = clk_hw_get_parent(hw);
 	int bestdiv;
 
 	/* if read only, just return current value */
@@ -356,6 +357,15 @@ static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
 		bestdiv &= div_mask(divider->width);
 		bestdiv = _get_div(divider->table, bestdiv, divider->flags,
 			divider->width);
+
+		/* Even a read-only clock can propagate a rate change */
+		if (clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT) {
+			if (!hw_parent)
+				return -EINVAL;
+
+			*prate = clk_hw_round_rate(hw_parent, rate * bestdiv);
+		}
+
 		return DIV_ROUND_UP_ULL((u64)*prate, bestdiv);
 	}
 
-- 
2.14.3