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[PATCH] clk: samsung: exynos5420: The EPLL rate table corrections

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  [PATCH] clk: samsung: exynos5420: The EPLL rate table corrections Sylwester Nawrocki <s.nawrocki@samsung.com> - 2017-07-21 13:30 +0200
    Re: [PATCH] clk: samsung: exynos5420: The EPLL rate table  corrections Sylwester Nawrocki <s.nawrocki@samsung.com> - 2017-07-31 14:30 +0200

#1693626 — [PATCH] clk: samsung: exynos5420: The EPLL rate table corrections

This patch fixes values of the EPLL K coefficient and changes
the EPLL output frequency values to match exactly what is
possible to achieve with given M, P, S, K coefficients.
This allows to avoid rounding errors and unexpected frequency
being set with clk_set_rate(), due to recalc_rate returning
different values than the PLL rate specified in the
exynos5420_epll_24mhz_tbl table. E.g. this prevents a case
where two consecutive clk_set_rate() calls with same argument
result in different PLL output frequency.

The PLL output frequencies have been calculated with formula:

f = fxtal * (M * 2^16 + K) / (P * 2^S) / 2^16

where fxtal = 24000000.

Fixes: 9842452acd ("clk: samsung: exynos542x: Add EPLL rate table")
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
---
 drivers/clk/samsung/clk-exynos5420.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/clk/samsung/clk-exynos5420.c b/drivers/clk/samsung/clk-exynos5420.c
index 0748a0b..9a6476a 100644
--- a/drivers/clk/samsung/clk-exynos5420.c
+++ b/drivers/clk/samsung/clk-exynos5420.c
@@ -1283,16 +1283,16 @@ static void __init exynos5420_clk_sleep_init(void) {}
 static const struct samsung_pll_rate_table exynos5420_epll_24mhz_tbl[] = {
 	PLL_36XX_RATE(600000000U, 100, 2, 1, 0),
 	PLL_36XX_RATE(400000000U, 200, 3, 2, 0),
-	PLL_36XX_RATE(393216000U, 197, 3, 2, 25690),
-	PLL_36XX_RATE(361267200U, 301, 5, 2, 3671),
+	PLL_36XX_RATE(393216003U, 197, 3, 2, -25690),
+	PLL_36XX_RATE(361267218U, 301, 5, 2, 3671),
 	PLL_36XX_RATE(200000000U, 200, 3, 3, 0),
-	PLL_36XX_RATE(196608000U, 197, 3, 3, -25690),
-	PLL_36XX_RATE(180633600U, 301, 5, 3, 3671),
-	PLL_36XX_RATE(131072000U, 131, 3, 3, 4719),
+	PLL_36XX_RATE(196608001U, 197, 3, 3, -25690),
+	PLL_36XX_RATE(180633609U, 301, 5, 3, 3671),
+	PLL_36XX_RATE(131072006U, 131, 3, 3, 4719),
 	PLL_36XX_RATE(100000000U, 200, 3, 4, 0),
-	PLL_36XX_RATE(65536000U, 131, 3, 4, 4719),
-	PLL_36XX_RATE(49152000U, 197, 3, 5, 25690),
-	PLL_36XX_RATE(32768000U, 131, 3, 5, 4719),
+	PLL_36XX_RATE( 65536003U, 131, 3, 4, 4719),
+	PLL_36XX_RATE( 49152000U, 197, 3, 5, -25690),
+	PLL_36XX_RATE( 32768001U, 131, 3, 5, 4719),
 };
 
 static struct samsung_pll_clock exynos5x_plls[nr_plls] __initdata = {
-- 
1.9.1

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#1699996 — Re: [PATCH] clk: samsung: exynos5420: The EPLL rate table corrections

On 07/21/2017 01:19 PM, Sylwester Nawrocki wrote:
> This patch fixes values of the EPLL K coefficient and changes
> the EPLL output frequency values to match exactly what is
> possible to achieve with given M, P, S, K coefficients.
> This allows to avoid rounding errors and unexpected frequency
> being set with clk_set_rate(), due to recalc_rate returning
> different values than the PLL rate specified in the
> exynos5420_epll_24mhz_tbl table. E.g. this prevents a case
> where two consecutive clk_set_rate() calls with same argument
> result in different PLL output frequency.
> 
> The PLL output frequencies have been calculated with formula:
> 
> f = fxtal * (M * 2^16  + K) / (P * 2^S) / 2^16
> 
> where fxtal = 24000000.
> 
> Fixes: 9842452acd ("clk: samsung: exynos542x: Add EPLL rate table")
> Signed-off-by: Sylwester Nawrocki<s.nawrocki@samsung.com>

Stephen, Mike,

Could you apply this patch directly for v4.12-rcX?
It fixes code added in v4.12.

-- 
Thanks,
Sylwester

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