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| author | Chen-Yu Tsai <wens@csie.org> | 2017-12-08 16:35:12 +0800 |
|---|---|---|
| committer | Maxime Ripard <maxime.ripard@free-electrons.com> | 2017-12-08 10:08:32 +0100 |
| commit | e952ca3c6b2ffdfbf9618e4bd3e9aad1ff3f5eb4 (patch) | |
| tree | 63c022815ebc73f810ae2b1a0edbab8ef1fd711d /drivers/clk/sunxi-ng | |
| parent | 10e6eb4f2c5b35ae71c9bc0db83d74238719b453 (diff) | |
| download | lwn-e952ca3c6b2ffdfbf9618e4bd3e9aad1ff3f5eb4.tar.gz lwn-e952ca3c6b2ffdfbf9618e4bd3e9aad1ff3f5eb4.zip | |
clk: sunxi-ng: sun8i: a83t: Use sigma-delta modulation for audio PLL
The audio blocks require specific clock rates. Until now we were using
the closest clock rate possible with integer N-M factors. This resulted
in audio playback being slightly slower than it should be.
The vendor kernel gets around this (for newer SoCs) by using sigma-delta
modulation to generate a fractional-N factor. This patch copies the
parameters for the A83T.
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Diffstat (limited to 'drivers/clk/sunxi-ng')
| -rw-r--r-- | drivers/clk/sunxi-ng/ccu-sun8i-a83t.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/drivers/clk/sunxi-ng/ccu-sun8i-a83t.c b/drivers/clk/sunxi-ng/ccu-sun8i-a83t.c index 06b69e433d0f..04a9c33f53f0 100644 --- a/drivers/clk/sunxi-ng/ccu-sun8i-a83t.c +++ b/drivers/clk/sunxi-ng/ccu-sun8i-a83t.c @@ -76,17 +76,26 @@ static struct ccu_mult pll_c1cpux_clk = { */ #define SUN8I_A83T_PLL_AUDIO_REG 0x008 +/* clock rates doubled for post divider */ +static struct ccu_sdm_setting pll_audio_sdm_table[] = { + { .rate = 45158400, .pattern = 0xc00121ff, .m = 29, .n = 54 }, + { .rate = 49152000, .pattern = 0xc000e147, .m = 30, .n = 61 }, +}; + static struct ccu_nm pll_audio_clk = { .enable = BIT(31), .lock = BIT(2), .n = _SUNXI_CCU_MULT_OFFSET_MIN_MAX(8, 8, 0, 12, 0), .m = _SUNXI_CCU_DIV(0, 6), .fixed_post_div = 2, + .sdm = _SUNXI_CCU_SDM(pll_audio_sdm_table, BIT(24), + 0x284, BIT(31)), .common = { .reg = SUN8I_A83T_PLL_AUDIO_REG, .lock_reg = CCU_SUN8I_A83T_LOCK_REG, .features = CCU_FEATURE_LOCK_REG | - CCU_FEATURE_FIXED_POSTDIV, + CCU_FEATURE_FIXED_POSTDIV | + CCU_FEATURE_SIGMA_DELTA_MOD, .hw.init = CLK_HW_INIT("pll-audio", "osc24M", &ccu_nm_ops, CLK_SET_RATE_UNGATE), }, |