Unverified Commit ef3e1b8a authored by Mark Brown's avatar Mark Brown
Browse files

ASoC: cs42l42: Fix handling of hard reset 

Merge series from Stefan Binding <sbinding@opensource.cirrus.com>:

These patches fix 3 problems with hard reset:
1. Ensure a minimum reset pulse width
2. Deal with ACPI overriding the requested default GPIO state
3. Avoid a race condition when hard-resetting a SoundWire peripheral
   that is already enumerated
parents 781118bc 2d066c6a

sound/soc/codecs/cs42l42-sdw.c

+20 −0
Original line number Diff line number Diff line
@@ -344,6 +344,16 @@ static int cs42l42_sdw_update_status(struct sdw_slave *peripheral, 
	switch (status) {

	case SDW_SLAVE_ATTACHED:

		dev_dbg(cs42l42->dev, "ATTACHED\n");



		/*

		 * The SoundWire core can report stale ATTACH notifications

		 * if we hard-reset CS42L42 in probe() but it had already been

		 * enumerated. Reject the ATTACH if we haven't yet seen an

		 * UNATTACH report for the device being in reset.

		 */

		if (cs42l42->sdw_waiting_first_unattach)

			break;



		/*

		 * Initialise codec, this only needs to be done once.

		 * When resuming from suspend, resume callback will handle re-init of codec,
@@ -354,6 +364,16 @@ static int cs42l42_sdw_update_status(struct sdw_slave *peripheral, 
		break;

	case SDW_SLAVE_UNATTACHED:

		dev_dbg(cs42l42->dev, "UNATTACHED\n");



		if (cs42l42->sdw_waiting_first_unattach) {

			/*

			 * SoundWire core has seen that CS42L42 is not on

			 * the bus so release RESET and wait for ATTACH.

			 */

			cs42l42->sdw_waiting_first_unattach = false;

			gpiod_set_value_cansleep(cs42l42->reset_gpio, 1);

		}



		break;

	default:

		break;

sound/soc/codecs/cs42l42.c

+20 −1
Original line number Diff line number Diff line
@@ -2320,6 +2320,25 @@ int cs42l42_common_probe(struct cs42l42_private *cs42l42, 


	if (cs42l42->reset_gpio) {

		dev_dbg(cs42l42->dev, "Found reset GPIO\n");



		/*

		 * ACPI can override the default GPIO state we requested

		 * so ensure that we start with RESET low.

		 */

		gpiod_set_value_cansleep(cs42l42->reset_gpio, 0);



		/* Ensure minimum reset pulse width */

		usleep_range(10, 500);



		/*

		 * On SoundWire keep the chip in reset until we get an UNATTACH

		 * notification from the SoundWire core. This acts as a

		 * synchronization point to reject stale ATTACH notifications

		 * if the chip was already enumerated before we reset it.

		 */

		if (cs42l42->sdw_peripheral)

			cs42l42->sdw_waiting_first_unattach = true;

		else

			gpiod_set_value_cansleep(cs42l42->reset_gpio, 1);

	}

	usleep_range(CS42L42_BOOT_TIME_US, CS42L42_BOOT_TIME_US * 2);

sound/soc/codecs/cs42l42.h

+1 −0
Original line number Diff line number Diff line
@@ -53,6 +53,7 @@ struct cs42l42_private { 
	u8 stream_use;

	bool hp_adc_up_pending;

	bool suspended;

	bool sdw_waiting_first_unattach;

	bool init_done;

};