From 2bd05db718cf452fe235c7c08083b2e60f787f3a Mon Sep 17 00:00:00 2001 From: Peter Ujfalusi Date: Sat, 14 Jan 2012 20:58:44 +0100 Subject: [PATCH] mfd: Avoid twl6040-codec PLL reconfiguration when not needed Do not reconfigure the PLL in case it has been configured already with the requested parameters. In case of different PLL configuration do only the needed changes. This can save considerable amount of time since we can avoid the defined protocol (with delays) for the PLL configuration. Signed-off-by: Peter Ujfalusi Signed-off-by: Samuel Ortiz --- drivers/mfd/twl6040-core.c | 125 ++++++++++++++++++++++--------------- 1 file changed, 74 insertions(+), 51 deletions(-) diff --git a/drivers/mfd/twl6040-core.c b/drivers/mfd/twl6040-core.c index c2088f4c4547..b2d8e512d3cb 100644 --- a/drivers/mfd/twl6040-core.c +++ b/drivers/mfd/twl6040-core.c @@ -326,23 +326,38 @@ int twl6040_set_pll(struct twl6040 *twl6040, int pll_id, hppllctl = twl6040_reg_read(twl6040, TWL6040_REG_HPPLLCTL); lppllctl = twl6040_reg_read(twl6040, TWL6040_REG_LPPLLCTL); + /* Force full reconfiguration when switching between PLL */ + if (pll_id != twl6040->pll) { + twl6040->sysclk = 0; + twl6040->mclk = 0; + } + switch (pll_id) { case TWL6040_SYSCLK_SEL_LPPLL: /* low-power PLL divider */ - switch (freq_out) { - case 17640000: - lppllctl |= TWL6040_LPLLFIN; - break; - case 19200000: - lppllctl &= ~TWL6040_LPLLFIN; - break; - default: - dev_err(twl6040->dev, - "freq_out %d not supported\n", freq_out); - ret = -EINVAL; - goto pll_out; + /* Change the sysclk configuration only if it has been canged */ + if (twl6040->sysclk != freq_out) { + switch (freq_out) { + case 17640000: + lppllctl |= TWL6040_LPLLFIN; + break; + case 19200000: + lppllctl &= ~TWL6040_LPLLFIN; + break; + default: + dev_err(twl6040->dev, + "freq_out %d not supported\n", + freq_out); + ret = -EINVAL; + goto pll_out; + } + twl6040_reg_write(twl6040, TWL6040_REG_LPPLLCTL, + lppllctl); } - twl6040_reg_write(twl6040, TWL6040_REG_LPPLLCTL, lppllctl); + + /* The PLL in use has not been change, we can exit */ + if (twl6040->pll == pll_id) + break; switch (freq_in) { case 32768: @@ -373,48 +388,56 @@ int twl6040_set_pll(struct twl6040 *twl6040, int pll_id, goto pll_out; } - hppllctl &= ~TWL6040_MCLK_MSK; + if (twl6040->mclk != freq_in) { + hppllctl &= ~TWL6040_MCLK_MSK; + + switch (freq_in) { + case 12000000: + /* PLL enabled, active mode */ + hppllctl |= TWL6040_MCLK_12000KHZ | + TWL6040_HPLLENA; + break; + case 19200000: + /* + * PLL disabled + * (enable PLL if MCLK jitter quality + * doesn't meet specification) + */ + hppllctl |= TWL6040_MCLK_19200KHZ; + break; + case 26000000: + /* PLL enabled, active mode */ + hppllctl |= TWL6040_MCLK_26000KHZ | + TWL6040_HPLLENA; + break; + case 38400000: + /* PLL enabled, active mode */ + hppllctl |= TWL6040_MCLK_38400KHZ | + TWL6040_HPLLENA; + break; + default: + dev_err(twl6040->dev, + "freq_in %d not supported\n", freq_in); + ret = -EINVAL; + goto pll_out; + } - switch (freq_in) { - case 12000000: - /* PLL enabled, active mode */ - hppllctl |= TWL6040_MCLK_12000KHZ | - TWL6040_HPLLENA; - break; - case 19200000: /* - * PLL disabled - * (enable PLL if MCLK jitter quality - * doesn't meet specification) + * enable clock slicer to ensure input waveform is + * square */ - hppllctl |= TWL6040_MCLK_19200KHZ; - break; - case 26000000: - /* PLL enabled, active mode */ - hppllctl |= TWL6040_MCLK_26000KHZ | - TWL6040_HPLLENA; - break; - case 38400000: - /* PLL enabled, active mode */ - hppllctl |= TWL6040_MCLK_38400KHZ | - TWL6040_HPLLENA; - break; - default: - dev_err(twl6040->dev, - "freq_in %d not supported\n", freq_in); - ret = -EINVAL; - goto pll_out; - } + hppllctl |= TWL6040_HPLLSQRENA; - /* enable clock slicer to ensure input waveform is square */ - hppllctl |= TWL6040_HPLLSQRENA; - - twl6040_reg_write(twl6040, TWL6040_REG_HPPLLCTL, hppllctl); - usleep_range(500, 700); - lppllctl |= TWL6040_HPLLSEL; - twl6040_reg_write(twl6040, TWL6040_REG_LPPLLCTL, lppllctl); - lppllctl &= ~TWL6040_LPLLENA; - twl6040_reg_write(twl6040, TWL6040_REG_LPPLLCTL, lppllctl); + twl6040_reg_write(twl6040, TWL6040_REG_HPPLLCTL, + hppllctl); + usleep_range(500, 700); + lppllctl |= TWL6040_HPLLSEL; + twl6040_reg_write(twl6040, TWL6040_REG_LPPLLCTL, + lppllctl); + lppllctl &= ~TWL6040_LPLLENA; + twl6040_reg_write(twl6040, TWL6040_REG_LPPLLCTL, + lppllctl); + } break; default: dev_err(twl6040->dev, "unknown pll id %d\n", pll_id); -- 2.20.1