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Commit 702ad49f authored by Hans de Goede's avatar Hans de Goede Committed by Greg Kroah-Hartman
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usb: typec: fusb302: Fix fusb302_handle_togdone_src Ra handling 



The FUSB302 will stop toggling with a FUSB_REG_STATUS1A_TOGSS_SRC? status,
as soon as it sees either Ra or Rd on a CC pin.

Before this commit fusb302_handle_togdone_src would assume that the toggle-
engine always stopped at the CC pin indicating the polarity, IOW it assumed
that it stopped at the pin connected to Rd. It did check the CC-status of
that pin, but it did not expect to get a CC-status of Ra and therefore
treated this as CC-open. This lead to the following 2 problems:

1) If a powered cable/adapter gets plugged in with Ra on CC1 and Rd on CC2
then 4 of 5 times when plugged in toggling will stop with a togdone_result
of FUSB_REG_STATUS1A_TOGSS_SRC1.  3/5th of the time the toggle-engine is
testing for being connected as a sink and after that it tests 1/5th of the
time for connected as a src through CC1 before finally testing the last
1/5th of the time for being a src connected through CC2.

This was a problem because we would only check the CC pin status for the
pin on which the toggling stopped which in this polarity 4 out of 5
times would be the Ra pin. The code before this commit would treat Ra as
CC-open and then restart toggling. Once toggling is restarted we are
guaranteed to end with FUSB_REG_STATUS1A_TOGSS_SRC1 as CC1 is tested first,
leading to a CC-status of Ra again and an infinite restart toggling loop.
So 4 out of 5 times when plugged in in this polarity a powered adapter
will not work.

2) Even if we happen to have the right polarity or 1/5th of the time in
the polarity with problem 1), we would report the non Rd pin as CC-open
rather then as Ra, resulting in the tcpm.c code not enabling Vconn which
is a problem for some adapters.

This commit fixes this by getting the CC-status of *both* pins and then
determining the polarity based on that, rather then on where the toggling
stopped.

Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
Acked-by: default avatarHeikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 32a155b1

drivers/usb/typec/tcpm/fusb302.c

+97 −52
Original line number Diff line number Diff line
@@ -1249,81 +1249,128 @@ static int fusb302_handle_togdone_snk(struct fusb302_chip *chip, 
	return ret;

}



static int fusb302_handle_togdone_src(struct fusb302_chip *chip,

				      u8 togdone_result)

/* On error returns < 0, otherwise a typec_cc_status value */

static int fusb302_get_src_cc_status(struct fusb302_chip *chip,

				     enum typec_cc_polarity cc_polarity,

				     enum typec_cc_status *cc)

{

	/*

	 * - set polarity (measure cc, vconn, tx)

	 * - set pull_up, pull_down

	 * - set cc1, cc2, and update to tcpm_port

	 * - set I_COMP interrupt on

	 */

	int ret = 0;

	u8 status0;

	u8 ra_mda = ra_mda_value[chip->src_current_status];

	u8 rd_mda = rd_mda_value[chip->src_current_status];

	bool ra_comp, rd_comp;

	enum typec_cc_polarity cc_polarity;

	enum typec_cc_status cc_status_active, cc1, cc2;

	u8 switches0_data, status0;

	int ret;



	/* set polarity and pull_up, pull_down */

	cc_polarity = (togdone_result == FUSB_REG_STATUS1A_TOGSS_SRC1) ?

		      TYPEC_POLARITY_CC1 : TYPEC_POLARITY_CC2;

	ret = fusb302_set_cc_polarity_and_pull(chip, cc_polarity, true, false);

	if (ret < 0) {

		fusb302_log(chip, "cannot set cc polarity %s, ret=%d",

			    cc_polarity_name[cc_polarity], ret);

	/* Step 1: Set switches so that we measure the right CC pin */

	switches0_data = (cc_polarity == TYPEC_POLARITY_CC1) ?

		FUSB_REG_SWITCHES0_CC1_PU_EN | FUSB_REG_SWITCHES0_MEAS_CC1 :

		FUSB_REG_SWITCHES0_CC2_PU_EN | FUSB_REG_SWITCHES0_MEAS_CC2;

	ret = fusb302_i2c_write(chip, FUSB_REG_SWITCHES0, switches0_data);

	if (ret < 0)

		return ret;

	}

	/* fusb302_set_cc_polarity() has set the correct measure block */



	fusb302_i2c_read(chip, FUSB_REG_SWITCHES0, &status0);

	fusb302_log(chip, "get_src_cc_status switches: 0x%0x", status0);



	/* Step 2: Set compararator volt to differentiate between Open and Rd */

	ret = fusb302_i2c_write(chip, FUSB_REG_MEASURE, rd_mda);

	if (ret < 0)

		return ret;



	usleep_range(50, 100);

	ret = fusb302_i2c_read(chip, FUSB_REG_STATUS0, &status0);

	if (ret < 0)

		return ret;

	rd_comp = !!(status0 & FUSB_REG_STATUS0_COMP);

	if (!rd_comp) {



	fusb302_log(chip, "get_src_cc_status rd_mda status0: 0x%0x", status0);

	if (status0 & FUSB_REG_STATUS0_COMP) {

		*cc = TYPEC_CC_OPEN;

		return 0;

	}



	/* Step 3: Set compararator input to differentiate between Rd and Ra. */

	ret = fusb302_i2c_write(chip, FUSB_REG_MEASURE, ra_mda);

	if (ret < 0)

		return ret;



	usleep_range(50, 100);

	ret = fusb302_i2c_read(chip, FUSB_REG_STATUS0, &status0);

	if (ret < 0)

		return ret;

		ra_comp = !!(status0 & FUSB_REG_STATUS0_COMP);



	fusb302_log(chip, "get_src_cc_status ra_mda status0: 0x%0x", status0);

	if (status0 & FUSB_REG_STATUS0_COMP)

		*cc = TYPEC_CC_RD;

	else

		*cc = TYPEC_CC_RA;



	return 0;

}



static int fusb302_handle_togdone_src(struct fusb302_chip *chip,

				      u8 togdone_result)

{

	/*

	 * - set polarity (measure cc, vconn, tx)

	 * - set pull_up, pull_down

	 * - set cc1, cc2, and update to tcpm_port

	 * - set I_COMP interrupt on

	 */

	int ret = 0;

	u8 rd_mda = rd_mda_value[chip->src_current_status];

	enum toggling_mode toggling_mode = chip->toggling_mode;

	enum typec_cc_polarity cc_polarity;

	enum typec_cc_status cc1, cc2;



	/*

	 * The toggle-engine will stop in a src state if it sees either Ra or

	 * Rd. Determine the status for both CC pins, starting with the one

	 * where toggling stopped, as that is where the switches point now.

	 */

	if (togdone_result == FUSB_REG_STATUS1A_TOGSS_SRC1)

		ret = fusb302_get_src_cc_status(chip, TYPEC_POLARITY_CC1, &cc1);

	else

		ret = fusb302_get_src_cc_status(chip, TYPEC_POLARITY_CC2, &cc2);

	if (ret < 0)

		return ret;

	/* we must turn off toggling before we can measure the other pin */

	ret = fusb302_set_toggling(chip, TOGGLING_MODE_OFF);

	if (ret < 0) {

		fusb302_log(chip, "cannot set toggling mode off, ret=%d", ret);

		return ret;

	}

	if (rd_comp)

		cc_status_active = TYPEC_CC_OPEN;

	else if (ra_comp)

		cc_status_active = TYPEC_CC_RD;

	/* get the status of the other pin */

	if (togdone_result == FUSB_REG_STATUS1A_TOGSS_SRC1)

		ret = fusb302_get_src_cc_status(chip, TYPEC_POLARITY_CC2, &cc2);

	else

		/* Ra is not supported, report as Open */

		cc_status_active = TYPEC_CC_OPEN;

	/* restart toggling if the cc status on the active line is OPEN */

	if (cc_status_active == TYPEC_CC_OPEN) {

		fusb302_log(chip, "restart toggling as CC_OPEN detected");

		ret = fusb302_set_toggling(chip, chip->toggling_mode);

		ret = fusb302_get_src_cc_status(chip, TYPEC_POLARITY_CC1, &cc1);

	if (ret < 0)

		return ret;



	/* determine polarity based on the status of both pins */

	if (cc1 == TYPEC_CC_RD &&

			(cc2 == TYPEC_CC_OPEN || cc2 == TYPEC_CC_RA)) {

		cc_polarity = TYPEC_POLARITY_CC1;

	} else if (cc2 == TYPEC_CC_RD &&

		    (cc1 == TYPEC_CC_OPEN || cc1 == TYPEC_CC_RA)) {

		cc_polarity = TYPEC_POLARITY_CC2;

	} else {

		fusb302_log(chip, "unexpected CC status cc1=%s, cc2=%s, restarting toggling",

			    typec_cc_status_name[cc1],

			    typec_cc_status_name[cc2]);

		return fusb302_set_toggling(chip, toggling_mode);

	}

	/* set polarity and pull_up, pull_down */

	ret = fusb302_set_cc_polarity_and_pull(chip, cc_polarity, true, false);

	if (ret < 0) {

		fusb302_log(chip, "cannot set cc polarity %s, ret=%d",

			    cc_polarity_name[cc_polarity], ret);

		return ret;

	}

	/* update tcpm with the new cc value */

	cc1 = (cc_polarity == TYPEC_POLARITY_CC1) ?

	      cc_status_active : TYPEC_CC_OPEN;

	cc2 = (cc_polarity == TYPEC_POLARITY_CC2) ?

	      cc_status_active : TYPEC_CC_OPEN;

	if ((chip->cc1 != cc1) || (chip->cc2 != cc2)) {

		chip->cc1 = cc1;

		chip->cc2 = cc2;

		tcpm_cc_change(chip->tcpm_port);

	}

	/* turn off toggling */

	ret = fusb302_set_toggling(chip, TOGGLING_MODE_OFF);

	if (ret < 0) {

		fusb302_log(chip,

			    "cannot set toggling mode off, ret=%d", ret);

		return ret;

	}

	/* set MDAC to Rd threshold, and unmask I_COMP for unplug detection */

	ret = fusb302_i2c_write(chip, FUSB_REG_MEASURE, rd_mda);

	if (ret < 0)
@@ -1509,9 +1556,7 @@ static irqreturn_t fusb302_irq_intn(int irq, void *dev_id) 
			    comp_result ? "true" : "false");

		if (comp_result) {

			/* cc level > Rd_threashold, detach */

			if (chip->cc_polarity == TYPEC_POLARITY_CC1)

			chip->cc1 = TYPEC_CC_OPEN;

			else

			chip->cc2 = TYPEC_CC_OPEN;

			tcpm_cc_change(chip->tcpm_port);

		}