ASoC: cs35l56: Wake transactions need to be issued twice

As the dummy wake is a toggling signal (either I2C or SPI activity) it
is not guaranteed to meet the minimum asserted hold time for a wake
signal. In this case the wake must guarantee rising edges separated by
at least the minimum hold time.

Signed-off-by: Simon Trimmer <simont@opensource.cirrus.com>
Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20231006111039.101914-3-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/include/sound/cs35l56.h b/include/sound/cs35l56.h
index 762b96b..8c18e8b 100644 (file)
--- a/include/sound/cs35l56.h
+++ b/include/sound/cs35l56.h
@@ -243,6 +243,7 @@
 #define CS35L56_HALO_STATE_POLL_US                     1000
 #define CS35L56_HALO_STATE_TIMEOUT_US                  50000
 #define CS35L56_RESET_PULSE_MIN_US                     1100
+#define CS35L56_WAKE_HOLD_TIME_US                      1000
 
 #define CS35L56_SDW1_PLAYBACK_PORT                     1
 #define CS35L56_SDW1_CAPTURE_PORT                      3

diff --git a/sound/soc/codecs/cs35l56-shared.c b/sound/soc/codecs/cs35l56-shared.c
index 68dc93b..953ba06 100644 (file)
--- a/sound/soc/codecs/cs35l56-shared.c
+++ b/sound/soc/codecs/cs35l56-shared.c
@@ -446,6 +446,32 @@ static const struct reg_sequence cs35l56_hibernate_wake_seq[] = {
        REG_SEQ0(CS35L56_DSP_VIRTUAL1_MBOX_1, CS35L56_MBOX_CMD_WAKEUP),
 };
 
+static void cs35l56_issue_wake_event(struct cs35l56_base *cs35l56_base)
+{
+       /*
+        * Dummy transactions to trigger I2C/SPI auto-wake. Issue two
+        * transactions to meet the minimum required time from the rising edge
+        * to the last falling edge of wake.
+        *
+        * It uses bypassed write because we must wake the chip before
+        * disabling regmap cache-only.
+        *
+        * This can NAK on I2C which will terminate the write sequence so the
+        * single-write sequence is issued twice.
+        */
+       regmap_multi_reg_write_bypassed(cs35l56_base->regmap,
+                                       cs35l56_hibernate_wake_seq,
+                                       ARRAY_SIZE(cs35l56_hibernate_wake_seq));
+
+       usleep_range(CS35L56_WAKE_HOLD_TIME_US, 2 * CS35L56_WAKE_HOLD_TIME_US);
+
+       regmap_multi_reg_write_bypassed(cs35l56_base->regmap,
+                                       cs35l56_hibernate_wake_seq,
+                                       ARRAY_SIZE(cs35l56_hibernate_wake_seq));
+
+       cs35l56_wait_control_port_ready();
+}
+
 int cs35l56_runtime_suspend_common(struct cs35l56_base *cs35l56_base)
 {
        unsigned int val;
@@ -500,17 +526,9 @@ int cs35l56_runtime_resume_common(struct cs35l56_base *cs35l56_base, bool is_sou
        if (!cs35l56_base->can_hibernate)
                goto out_sync;
 
-       if (!is_soundwire) {
-               /*
-                * Dummy transaction to trigger I2C/SPI auto-wake. This will NAK on I2C.
-                * Must be done before releasing cache-only.
-                */
-               regmap_multi_reg_write_bypassed(cs35l56_base->regmap,
-                                               cs35l56_hibernate_wake_seq,
-                                               ARRAY_SIZE(cs35l56_hibernate_wake_seq));
-
-               cs35l56_wait_control_port_ready();
-       }
+       /* Must be done before releasing cache-only */
+       if (!is_soundwire)
+               cs35l56_issue_wake_event(cs35l56_base);
 
 out_sync:
        regcache_cache_only(cs35l56_base->regmap, false);
@@ -578,13 +596,14 @@ int cs35l56_hw_init(struct cs35l56_base *cs35l56_base)
        unsigned int devid, revid, otpid, secured;
 
        /*
-        * If the system is not using a reset_gpio then issue a
-        * dummy read to force a wakeup.
+        * When the system is not using a reset_gpio ensure the device is
+        * awake, otherwise the device has just been released from reset and
+        * the driver must wait for the control port to become usable.
         */
        if (!cs35l56_base->reset_gpio)
-               regmap_read(cs35l56_base->regmap, CS35L56_DSP_VIRTUAL1_MBOX_1, &devid);
-
-       cs35l56_wait_control_port_ready();
+               cs35l56_issue_wake_event(cs35l56_base);
+       else
+               cs35l56_wait_control_port_ready();
 
        /*
         * The HALO_STATE register is in different locations on Ax and B0