Commit e6431a0c authored by Chuck Ritola's avatar Chuck Ritola Committed by Mauro Carvalho Chehab
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media: dvb-frontends: a8293: fix LNB powerup failure in PCTV 461e 

Fixes a8293 failure to raise LNB voltage in PCTV 461e DVB-S2 Stick
affecting multiple users over several years as found here:

http://www.linuxquestions.org/questions/linux-hardware-18/pctv-dvb-s2-stick-461e-not-feeding-lnb-4175529374/
https://www.linuxtv.org/wiki/index.php/Pinnacle_PCTV_DVB-S2_Stick_(461e)
https://github.com/OpenELEC/OpenELEC.tv/issues/3731

Caused by vIN undervoltage lockout (status register bit 7) when raising LNB to 18V.
Addressed by using the higher-precision voltages available on the a8293 to gradually
increase (slew) the voltage when voltage increases are requested.

Adds volt_slew_nanos_per_mv to a8293_platform_data struct for specifying slew rate.
If value is <1 or non-sane (>1600), the original no-slew version for a8293_set_voltage is used.

Link: https://lore.kernel.org/linux-media/20211231035326.6759-1-cjritola@gmail.com


[mchehab: fixed some coding style issues]
Signed-off-by: default avatarChuck Ritola <cjritola@gmail.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@kernel.org>
parent b5411dd4

drivers/media/dvb-frontends/a8293.c

+152 −3
Original line number Diff line number Diff line
@@ -7,12 +7,139 @@ 


#include "a8293.h"



#define A8293_FLAG_ODT			0x10



struct a8293_dev {

	struct i2c_client *client;

	u8 reg[2];

	int volt_slew_nanos_per_mv;

};



static int a8293_set_voltage(struct dvb_frontend *fe,

/*

 * When increasing voltage, do so in minimal steps over time, minimizing

 * risk of vIN undervoltage.

 */



static int a8293_set_voltage_slew(struct a8293_dev *dev,

				  struct i2c_client *client,

				  enum fe_sec_voltage fe_sec_voltage,

				  int min_nanos_per_mv)

{

	int ret;

	u8 reg0, reg1;

	int new_volt_idx;

	const int idx_to_mv[] = {

		0,    12709, 13042, 13375, 14042, 15042, 18042, 18709, 19042

	};

	const u8 idx_to_reg[] = {

		0x00, 0x20,  0x21,  0x22,  0x24,  0x27,  0x28,  0x2A,  0x2B

	};

	int this_volt_idx;

	u8 status;

	int prev_volt_idx;



	dev_dbg(&client->dev, "set_voltage_slew fe_sec_voltage=%d\n",

		fe_sec_voltage);



	/* Read status register to clear any stale faults. */

	ret = i2c_master_recv(client, &status, 1);

	if (ret < 0)

		goto err;



	/* Determine previous voltage */

	switch (dev->reg[0] & 0x2F) {

	case 0x00:

		prev_volt_idx = 0;

		break;

	case 0x20:

		prev_volt_idx = 1;

		break;

	case 0x21:

		prev_volt_idx = 2;

		break;

	case 0x22:

		prev_volt_idx = 3;

		break;

	case 0x24:

		prev_volt_idx = 4;

		break;

	case 0x27:

		prev_volt_idx = 5;

		break;

	case 0x28:

		prev_volt_idx = 6;

		break;

	case 0x2A:

		prev_volt_idx = 7;

		break;

	case 0x2B:

		prev_volt_idx = 8;

		break;

	default:

		prev_volt_idx = 0;

	}



	/* Determine new voltage */

	switch (fe_sec_voltage) {

	case SEC_VOLTAGE_OFF:

		new_volt_idx = 0;

		break;

	case SEC_VOLTAGE_13:

		new_volt_idx = 2;

		break;

	case SEC_VOLTAGE_18:

		new_volt_idx = 6;

		break;

	default:

		ret = -EINVAL;

		goto err;

	}



	/* Slew to new voltage if new voltage is greater than current voltage */

	this_volt_idx = prev_volt_idx;

	if (this_volt_idx < new_volt_idx) {

		while (this_volt_idx < new_volt_idx) {

			int delta_mv = idx_to_mv[this_volt_idx+1] - idx_to_mv[this_volt_idx];

			int min_wait_time = delta_mv * min_nanos_per_mv;



			reg0 = idx_to_reg[this_volt_idx+1];

			reg0 |= A8293_FLAG_ODT;



			ret = i2c_master_send(client, &reg0, 1);

			if (ret < 0)

				goto err;

			dev->reg[0] = reg0;

			this_volt_idx++;

			usleep_range(min_wait_time, min_wait_time * 2);

		}

	} else { /* Else just set the voltage */

		reg0 = idx_to_reg[new_volt_idx];

		reg0 |= A8293_FLAG_ODT;

		ret = i2c_master_send(client, &reg0, 1);

		if (ret < 0)

			goto err;

		dev->reg[0] = reg0;

	}



	/* TMODE=0, TGATE=1 */

	reg1 = 0x82;

	if (reg1 != dev->reg[1]) {

		ret = i2c_master_send(client, &reg1, 1);

		if (ret < 0)

			goto err;

		dev->reg[1] = reg1;

	}



	usleep_range(1500, 5000);



	return 0;

err:

	dev_dbg(&client->dev, "failed=%d\n", ret);

	return ret;

}





static int a8293_set_voltage_noslew(struct dvb_frontend *fe,

				    enum fe_sec_voltage fe_sec_voltage)

{

	struct a8293_dev *dev = fe->sec_priv;
@@ -20,7 +147,8 @@ static int a8293_set_voltage(struct dvb_frontend *fe, 
	int ret;

	u8 reg0, reg1;



	dev_dbg(&client->dev, "fe_sec_voltage=%d\n", fe_sec_voltage);

	dev_dbg(&client->dev, "set_voltage_noslew fe_sec_voltage=%d\n",

		fe_sec_voltage);



	switch (fe_sec_voltage) {

	case SEC_VOLTAGE_OFF:
@@ -62,6 +190,26 @@ static int a8293_set_voltage(struct dvb_frontend *fe, 
	return ret;

}



static int a8293_set_voltage(struct dvb_frontend *fe,

			     enum fe_sec_voltage fe_sec_voltage)

{

	struct a8293_dev *dev = fe->sec_priv;

	struct i2c_client *client = dev->client;

	int volt_slew_nanos_per_mv = dev->volt_slew_nanos_per_mv;



	dev_dbg(&client->dev, "set_voltage volt_slew_nanos_per_mv=%d\n",

		volt_slew_nanos_per_mv);



	/* Use slew version if slew rate is set to a sane value */

	if (volt_slew_nanos_per_mv > 0 && volt_slew_nanos_per_mv < 1600)

		a8293_set_voltage_slew(dev, client, fe_sec_voltage,

				       volt_slew_nanos_per_mv);

	else

		a8293_set_voltage_noslew(fe, fe_sec_voltage);



	return 0;

}



static int a8293_probe(struct i2c_client *client)

{

	struct a8293_dev *dev;
@@ -77,6 +225,7 @@ static int a8293_probe(struct i2c_client *client) 
	}



	dev->client = client;

	dev->volt_slew_nanos_per_mv = pdata->volt_slew_nanos_per_mv;



	/* check if the SEC is there */

	ret = i2c_master_recv(client, buf, 2);

drivers/media/dvb-frontends/a8293.h

+3 −0
Original line number Diff line number Diff line
@@ -18,9 +18,12 @@ 
/**

 * struct a8293_platform_data - Platform data for the a8293 driver

 * @dvb_frontend: DVB frontend.

 * @volt_slew_nanos_per_mv: Slew rate when increasing LNB voltage,

 *	 in nanoseconds per millivolt.

 */

struct a8293_platform_data {

	struct dvb_frontend *dvb_frontend;

	int volt_slew_nanos_per_mv;

};



#endif /* A8293_H */

drivers/media/usb/em28xx/em28xx-dvb.c

+6 −0
Original line number Diff line number Diff line
@@ -1204,6 +1204,12 @@ static int em28178_dvb_init_pctv_461e(struct em28xx *dev) 


	/* attach SEC */

	a8293_pdata.dvb_frontend = dvb->fe[0];

	/*

	 * 461e has a tendency to have vIN undervoltage troubles.

	 * Slew mitigates this.

	 */

	a8293_pdata.volt_slew_nanos_per_mv = 20;



	dvb->i2c_client_sec = dvb_module_probe("a8293", NULL,

					       &dev->i2c_adap[dev->def_i2c_bus],

					       0x08, &a8293_pdata);