linux-kernel - [PATCH 4.16 127/161] clk: samsung: exynos7: Fix PLL rates

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Message-Id: <20180524093033.528569490@linuxfoundation.org>
Date:   Thu, 24 May 2018 11:39:12 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Andrzej Hajda <a.hajda@...sung.com>,
        Tomasz Figa <tomasz.figa@...il.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Sylwester Nawrocki <s.nawrocki@...sung.com>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.16 127/161] clk: samsung: exynos7: Fix PLL rates

4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andrzej Hajda <a.hajda@...sung.com>

[ Upstream commit 7e4db0c2836e892766565965207eee051c8037b9 ]

Rates declared in PLL rate tables should match exactly rates calculated from
the PLL coefficients. If that is not the case, rate of the PLL's child clock
might be set not as expected. For instance, if in the PLL rates table we have
a 393216000 Hz entry and the real value as returned by the PLL's recalc_rate
callback is 393216003, after setting PLL's clk rate to 393216000 clk_get_rate
will return 393216003. If we now attempt to set rate of a PLL's child divider
clock to 393216000/2 its rate will be 131072001, rather than 196608000.
That is, the divider will be set to 3 instead of 2, because 393216003/2 is
greater than 196608000.

To fix this issue declared rates are changed to exactly match rates generated
by the PLL, as calculated from the P, M, S, K coefficients.

Signed-off-by: Andrzej Hajda <a.hajda@...sung.com>
Acked-by: Tomasz Figa <tomasz.figa@...il.com>
Acked-by: Chanwoo Choi <cw00.choi@...sung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@...sung.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/clk/samsung/clk-exynos7.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/clk/samsung/clk-exynos7.c
+++ b/drivers/clk/samsung/clk-exynos7.c
@@ -140,7 +140,7 @@ static const struct samsung_div_clock to
 };

 static const struct samsung_pll_rate_table pll1460x_24mhz_tbl[] __initconst = {
-	PLL_36XX_RATE(491520000, 20, 1, 0, 31457),
+	PLL_36XX_RATE(491519897, 20, 1, 0, 31457),
 	{},
 };