From de344851919493033cdaa5736b2bfbcb05b50038 Mon Sep 17 00:00:00 2001 From: Chen-Yu Tsai Date: Thu, 12 Oct 2017 16:37:02 +0800 Subject: [PATCH] clk: sunxi-ng: sun4i: 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 A10 and A20. Signed-off-by: Chen-Yu Tsai Signed-off-by: Maxime Ripard --- drivers/clk/sunxi-ng/ccu-sun4i-a10.c | 26 ++++++++++++++++++++------ 1 file changed, 20 insertions(+), 6 deletions(-) diff --git a/drivers/clk/sunxi-ng/ccu-sun4i-a10.c b/drivers/clk/sunxi-ng/ccu-sun4i-a10.c index a48fde191c0a..ffa5dac221e4 100644 --- a/drivers/clk/sunxi-ng/ccu-sun4i-a10.c +++ b/drivers/clk/sunxi-ng/ccu-sun4i-a10.c @@ -28,6 +28,7 @@ #include "ccu_nkmp.h" #include "ccu_nm.h" #include "ccu_phase.h" +#include "ccu_sdm.h" #include "ccu-sun4i-a10.h" @@ -51,16 +52,29 @@ static struct ccu_nkmp pll_core_clk = { * 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 SUN4I_PLL_AUDIO_REG 0x008 + +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 struct ccu_nm pll_audio_base_clk = { .enable = BIT(31), .n = _SUNXI_CCU_MULT_OFFSET(8, 7, 0), .m = _SUNXI_CCU_DIV_OFFSET(0, 5, 0), + .sdm = _SUNXI_CCU_SDM(pll_audio_sdm_table, 0, + 0x00c, BIT(31)), .common = { .reg = 0x008, + .features = CCU_FEATURE_SIGMA_DELTA_MOD, .hw.init = CLK_HW_INIT("pll-audio-base", "hosc", &ccu_nm_ops, @@ -1021,9 +1035,9 @@ static struct ccu_common *sun4i_sun7i_ccu_clks[] = { &out_b_clk.common }; -/* Post-divider for pll-audio is hardcoded to 4 */ +/* Post-divider for pll-audio is hardcoded to 1 */ 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", @@ -1420,10 +1434,10 @@ static void __init sun4i_ccu_init(struct device_node *node, return; } - /* Force the PLL-Audio-1x divider to 4 */ + /* Force the PLL-Audio-1x divider to 1 */ val = readl(reg + SUN4I_PLL_AUDIO_REG); val &= ~GENMASK(29, 26); - writel(val | (4 << 26), reg + SUN4I_PLL_AUDIO_REG); + writel(val | (1 << 26), reg + SUN4I_PLL_AUDIO_REG); /* * Use the peripheral PLL6 as the AHB parent, instead of CPU /