From ee6501d69217a887cb496c42ff97ba43adff4ab1 Mon Sep 17 00:00:00 2001 From: Chen-Yu Tsai Date: Thu, 12 Oct 2017 16:37:04 +0800 Subject: [PATCH] clk: sunxi-ng: sun6i: 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. As the PLL hardware is identical in most chips, we can back port the settings from the newer SoC, in this case the H3, onto the A31. Signed-off-by: Chen-Yu Tsai Signed-off-by: Maxime Ripard --- drivers/clk/sunxi-ng/ccu-sun6i-a31.c | 38 ++++++++++++++++++---------- 1 file changed, 25 insertions(+), 13 deletions(-) diff --git a/drivers/clk/sunxi-ng/ccu-sun6i-a31.c b/drivers/clk/sunxi-ng/ccu-sun6i-a31.c index 241fb13f1c06..72b16ed1012b 100644 --- a/drivers/clk/sunxi-ng/ccu-sun6i-a31.c +++ b/drivers/clk/sunxi-ng/ccu-sun6i-a31.c @@ -31,6 +31,7 @@ #include "ccu_nkmp.h" #include "ccu_nm.h" #include "ccu_phase.h" +#include "ccu_sdm.h" #include "ccu-sun6i-a31.h" @@ -48,18 +49,29 @@ static SUNXI_CCU_NKM_WITH_GATE_LOCK(pll_cpu_clk, "pll-cpu", * the base (2x, 4x and 8x), and one variable divider (the one true * pll audio). * - * We don't have any need for the variable divider for now, so we just - * hardcode it to match with the clock names + * With sigma-delta modulation for fractional-N on the audio PLL, + * we have to use specific dividers. This means the variable divider + * can no longer be used, as the audio codec requests the exact clock + * rates we support through this mechanism. So we now hard code the + * variable divider to 1. This means the clock rates will no longer + * match the clock names. */ #define SUN6I_A31_PLL_AUDIO_REG 0x008 -static SUNXI_CCU_NM_WITH_GATE_LOCK(pll_audio_base_clk, "pll-audio-base", - "osc24M", 0x008, - 8, 7, /* N */ - 0, 5, /* M */ - BIT(31), /* gate */ - BIT(28), /* lock */ - CLK_SET_RATE_UNGATE); +static struct ccu_sdm_setting pll_audio_sdm_table[] = { + { .rate = 22579200, .pattern = 0xc0010d84, .m = 8, .n = 7 }, + { .rate = 24576000, .pattern = 0xc000ac02, .m = 14, .n = 14 }, +}; + +static SUNXI_CCU_NM_WITH_SDM_GATE_LOCK(pll_audio_base_clk, "pll-audio-base", + "osc24M", 0x008, + 8, 7, /* N */ + 0, 5, /* M */ + pll_audio_sdm_table, BIT(24), + 0x284, BIT(31), + BIT(31), /* gate */ + BIT(28), /* lock */ + CLK_SET_RATE_UNGATE); static SUNXI_CCU_NM_WITH_FRAC_GATE_LOCK(pll_video0_clk, "pll-video0", "osc24M", 0x010, @@ -950,9 +962,9 @@ static struct ccu_common *sun6i_a31_ccu_clks[] = { &out_c_clk.common, }; -/* We hardcode the divider to 4 for now */ +/* We hardcode the divider to 1 for now */ static CLK_FIXED_FACTOR(pll_audio_clk, "pll-audio", - "pll-audio-base", 4, 1, CLK_SET_RATE_PARENT); + "pll-audio-base", 1, 1, CLK_SET_RATE_PARENT); static CLK_FIXED_FACTOR(pll_audio_2x_clk, "pll-audio-2x", "pll-audio-base", 2, 1, CLK_SET_RATE_PARENT); static CLK_FIXED_FACTOR(pll_audio_4x_clk, "pll-audio-4x", @@ -1221,10 +1233,10 @@ static void __init sun6i_a31_ccu_setup(struct device_node *node) return; } - /* Force the PLL-Audio-1x divider to 4 */ + /* Force the PLL-Audio-1x divider to 1 */ val = readl(reg + SUN6I_A31_PLL_AUDIO_REG); val &= ~GENMASK(19, 16); - writel(val | (3 << 16), reg + SUN6I_A31_PLL_AUDIO_REG); + writel(val | (0 << 16), reg + SUN6I_A31_PLL_AUDIO_REG); /* Force PLL-MIPI to MIPI mode */ val = readl(reg + SUN6I_A31_PLL_MIPI_REG); -- 2.45.2