ASoC: cs42l42: PLL must be running when changing MCLK_SRC_SEL

Both SCLK and PLL clocks must be running to drive the glitch-free mux
behind MCLK_SRC_SEL and complete the switchover.

This patch moves the writing of MCLK_SRC_SEL to when the PLL is started
and stopped, so that it only transitions while the PLL is running.
The unconditional write MCLK_SRC_SEL=0 in cs42l42_mute_stream() is safe
because if the PLL is not running MCLK_SRC_SEL is already 0.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Fixes: 43fc357199f9 ("ASoC: cs42l42: Set clock source for both ways of stream")
Link: https://lore.kernel.org/r/20210805161111.10410-1-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/sound/soc/codecs/cs42l42.c b/sound/soc/codecs/cs42l42.c
index a00dc3c..c96549f 100644 (file)
--- a/sound/soc/codecs/cs42l42.c
+++ b/sound/soc/codecs/cs42l42.c
@@ -619,6 +619,8 @@ static int cs42l42_pll_config(struct snd_soc_component *component)
 
        for (i = 0; i < ARRAY_SIZE(pll_ratio_table); i++) {
                if (pll_ratio_table[i].sclk == clk) {
+                       cs42l42->pll_config = i;
+
                        /* Configure the internal sample rate */
                        snd_soc_component_update_bits(component, CS42L42_MCLK_CTL,
                                        CS42L42_INTERNAL_FS_MASK,
@@ -627,14 +629,9 @@ static int cs42l42_pll_config(struct snd_soc_component *component)
                                        (pll_ratio_table[i].mclk_int !=
                                        24000000)) <<
                                        CS42L42_INTERNAL_FS_SHIFT);
-                       /* Set the MCLK src (PLL or SCLK) and the divide
-                        * ratio
-                        */
+
                        snd_soc_component_update_bits(component, CS42L42_MCLK_SRC_SEL,
-                                       CS42L42_MCLK_SRC_SEL_MASK |
                                        CS42L42_MCLKDIV_MASK,
-                                       (pll_ratio_table[i].mclk_src_sel
-                                       << CS42L42_MCLK_SRC_SEL_SHIFT) |
                                        (pll_ratio_table[i].mclk_div <<
                                        CS42L42_MCLKDIV_SHIFT));
                        /* Set up the LRCLK */
@@ -892,13 +889,21 @@ static int cs42l42_mute_stream(struct snd_soc_dai *dai, int mute, int stream)
                         */
                        regmap_multi_reg_write(cs42l42->regmap, cs42l42_to_osc_seq,
                                               ARRAY_SIZE(cs42l42_to_osc_seq));
+
+                       /* Must disconnect PLL before stopping it */
+                       snd_soc_component_update_bits(component,
+                                                     CS42L42_MCLK_SRC_SEL,
+                                                     CS42L42_MCLK_SRC_SEL_MASK,
+                                                     0);
+                       usleep_range(100, 200);
+
                        snd_soc_component_update_bits(component, CS42L42_PLL_CTL1,
                                                      CS42L42_PLL_START_MASK, 0);
                }
        } else {
                if (!cs42l42->stream_use) {
                        /* SCLK must be running before codec unmute */
-                       if ((cs42l42->bclk < 11289600) && (cs42l42->sclk < 11289600)) {
+                       if (pll_ratio_table[cs42l42->pll_config].mclk_src_sel) {
                                snd_soc_component_update_bits(component, CS42L42_PLL_CTL1,
                                                              CS42L42_PLL_START_MASK, 1);
 
@@ -919,6 +924,12 @@ static int cs42l42_mute_stream(struct snd_soc_dai *dai, int mute, int stream)
                                                               CS42L42_PLL_LOCK_TIMEOUT_US);
                                if (ret < 0)
                                        dev_warn(component->dev, "PLL failed to lock: %d\n", ret);
+
+                               /* PLL must be running to drive glitchless switch logic */
+                               snd_soc_component_update_bits(component,
+                                                             CS42L42_MCLK_SRC_SEL,
+                                                             CS42L42_MCLK_SRC_SEL_MASK,
+                                                             CS42L42_MCLK_SRC_SEL_MASK);
                        }
 
                        /* Mark SCLK as present, turn off internal oscillator */

diff --git a/sound/soc/codecs/cs42l42.h b/sound/soc/codecs/cs42l42.h
index 7bf05ff..3dfeaf6 100644 (file)
--- a/sound/soc/codecs/cs42l42.h
+++ b/sound/soc/codecs/cs42l42.h
@@ -775,6 +775,7 @@ struct  cs42l42_private {
        struct gpio_desc *reset_gpio;
        struct completion pdn_done;
        struct snd_soc_jack *jack;
+       int pll_config;
        int bclk;
        u32 sclk;
        u32 srate;