From: Rajan Vaja <rajan.vaja@xilinx.com>
To: mturquette@baylibre.com, sboyd@kernel.org, robh+dt@kernel.org,
mark.rutland@arm.com, michal.simek@xilinx.com,
jolly.shah@xilinx.com, m.tretter@pengutronix.de,
gustavo@embeddedor.com, tejas.patel@xilinx.com,
nava.manne@xilinx.com, mdf@kernel.org
Cc: linux-clk@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Rajan Vaja <rajan.vaja@xilinx.com>
Subject: [PATCH v3 5/6] clk: zynqmp: Fix divider calculation
Date: Wed, 4 Dec 2019 22:35:58 -0800 [thread overview]
Message-ID: <1575527759-26452-6-git-send-email-rajan.vaja@xilinx.com> (raw)
In-Reply-To: <1575527759-26452-1-git-send-email-rajan.vaja@xilinx.com>
zynqmp_clk_divider_round_rate() returns actual divider value
after calculating from parent rate and desired rate, even though
that rate is not supported by single divider of hardware. It is
also possible that such divisor value can be achieved through 2
different dividers. As, Linux tries to set such divisor value(out
of range) in single divider set divider is getting failed.
Fix the same by computing best possible combination of two
divisors which provides more accurate clock rate.
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Tejas Patel <tejas.patel@xilinx.com>
Signed-off-by: Rajan Vaja <rajan.vaja@xilinx.com>
---
drivers/clk/zynqmp/divider.c | 46 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 46 insertions(+)
diff --git a/drivers/clk/zynqmp/divider.c b/drivers/clk/zynqmp/divider.c
index aea52cd..e0d49cc 100644
--- a/drivers/clk/zynqmp/divider.c
+++ b/drivers/clk/zynqmp/divider.c
@@ -89,6 +89,42 @@ static unsigned long zynqmp_clk_divider_recalc_rate(struct clk_hw *hw,
return DIV_ROUND_UP_ULL(parent_rate, value);
}
+static void zynqmp_get_divider2_val(struct clk_hw *hw,
+ unsigned long rate,
+ unsigned long parent_rate,
+ struct zynqmp_clk_divider *divider,
+ int *bestdiv)
+{
+ int div1;
+ int div2;
+ long error = LONG_MAX;
+ struct clk_hw *parent_hw = clk_hw_get_parent(hw);
+ struct zynqmp_clk_divider *pdivider = to_zynqmp_clk_divider(parent_hw);
+
+ if (!pdivider)
+ return;
+
+ *bestdiv = 1;
+ for (div1 = 1; div1 <= pdivider->max_div;) {
+ for (div2 = 1; div2 <= divider->max_div;) {
+ long new_error = ((parent_rate / div1) / div2) - rate;
+
+ if (abs(new_error) < abs(error)) {
+ *bestdiv = div2;
+ error = new_error;
+ }
+ if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
+ div2 = div2 << 1;
+ else
+ div2++;
+ }
+ if (pdivider->flags & CLK_DIVIDER_POWER_OF_TWO)
+ div1 = div1 << 1;
+ else
+ div1++;
+ }
+}
+
/**
* zynqmp_clk_divider_round_rate() - Round rate of divider clock
* @hw: handle between common and hardware-specific interfaces
@@ -126,6 +162,16 @@ static long zynqmp_clk_divider_round_rate(struct clk_hw *hw,
bestdiv = zynqmp_divider_get_val(*prate, rate);
+ /*
+ * In case of two divisors, compute best divider values and return
+ * divider2 value based on compute value. div1 will be automatically
+ * set to optimum based on required total divider value.
+ */
+ if (div_type == TYPE_DIV2 &&
+ (clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) {
+ zynqmp_get_divider2_val(hw, rate, *prate, divider, &bestdiv);
+ }
+
if ((clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT) && divider->is_frac)
bestdiv = rate % *prate ? 1 : bestdiv;
*prate = rate * bestdiv;
--
2.7.4
next prev parent reply other threads:[~2019-12-05 6:38 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-12 13:16 [PATCH 0/7] clk: zynqmp: Extend and fix zynqmp clock driver Rajan Vaja
2019-11-12 13:16 ` [PATCH 1/7] dt-bindings: clock: Add bindings for versal " Rajan Vaja
2019-11-12 22:51 ` Stephen Boyd
2019-11-18 17:30 ` Rob Herring
2019-11-12 13:16 ` [PATCH 2/7] clk: zynqmp: Extend driver for versal Rajan Vaja
2019-11-12 13:16 ` [PATCH 3/7] clk: zynqmp: Warn user if clock user are more than allowed Rajan Vaja
2019-11-21 14:31 ` Michael Tretter
2019-11-12 13:16 ` [PATCH 4/7] clk: zynqmp: Add support for get max divider Rajan Vaja
2019-11-21 14:33 ` Michael Tretter
2019-11-12 13:16 ` [PATCH 5/7] clk: zynqmp: Fix divider calculation Rajan Vaja
2019-11-12 13:16 ` [PATCH 6/7] clk: zynqmp: Add support for clock with CLK_DIVIDER_POWER_OF_TWO flag Rajan Vaja
2019-11-12 13:16 ` [PATCH 7/7] clk: zynqmp: Fix fractional clock check Rajan Vaja
2019-11-21 14:41 ` Michael Tretter
2019-11-22 9:43 ` [PATCH v2 0/6] clk: zynqmp: Extend and fix zynqmp clock driver Rajan Vaja
2019-11-22 9:43 ` [PATCH v2 1/6] dt-bindings: clock: Add bindings for versal " Rajan Vaja
2019-12-04 19:53 ` Rob Herring
2019-11-22 9:43 ` [PATCH v2 2/6] clk: zynqmp: Extend driver for versal Rajan Vaja
2019-11-22 9:43 ` [PATCH v2 3/6] clk: zynqmp: Warn user if clock user are more than allowed Rajan Vaja
2019-11-22 9:43 ` [PATCH v2 4/6] clk: zynqmp: Add support for get max divider Rajan Vaja
2019-11-22 9:43 ` [PATCH v2 5/6] clk: zynqmp: Fix divider calculation Rajan Vaja
2019-11-22 9:43 ` [PATCH v2 6/6] clk: zynqmp: Add support for clock with CLK_DIVIDER_POWER_OF_TWO flag Rajan Vaja
2019-12-05 6:35 ` [PATCH v3 0/6] clk: zynqmp: Extend and fix zynqmp clock driver Rajan Vaja
2019-12-05 6:35 ` [PATCH v3 1/6] dt-bindings: clock: Add bindings for versal " Rajan Vaja
2020-01-23 22:58 ` Stephen Boyd
2019-12-05 6:35 ` [PATCH v3 2/6] clk: zynqmp: Extend driver for versal Rajan Vaja
2020-01-23 22:58 ` Stephen Boyd
2019-12-05 6:35 ` [PATCH v3 3/6] clk: zynqmp: Warn user if clock user are more than allowed Rajan Vaja
2020-01-23 22:58 ` Stephen Boyd
2019-12-05 6:35 ` [PATCH v3 4/6] clk: zynqmp: Add support for get max divider Rajan Vaja
2020-01-23 22:58 ` Stephen Boyd
2019-12-05 6:35 ` Rajan Vaja [this message]
2020-01-23 22:58 ` [PATCH v3 5/6] clk: zynqmp: Fix divider calculation Stephen Boyd
2019-12-05 6:35 ` [PATCH v3 6/6] clk: zynqmp: Add support for clock with CLK_DIVIDER_POWER_OF_TWO flag Rajan Vaja
2020-01-23 22:59 ` Stephen Boyd
2019-12-12 15:20 ` [PATCH v3 0/6] clk: zynqmp: Extend and fix zynqmp clock driver Michal Simek
2020-01-16 11:41 ` Rajan Vaja
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