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| /openbmc/linux/drivers/clk/samsung/ |
| H A D | clk-exynos5420.c | 5b30850b Fri Jul 21 06:19:50 CDT 2017 Sylwester Nawrocki <s.nawrocki@samsung.com> 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>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
5b30850b Fri Jul 21 06:19:50 CDT 2017 Sylwester Nawrocki <s.nawrocki@samsung.com> 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>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
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