Re: [PATCH] media: dvb-frontends: a8293: fix LNB powerup failure in PCTV 461e

From: Mauro Carvalho Chehab
Date: Tue Dec 14 2021 - 08:37:48 EST

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Em Thu, 18 Nov 2021 21:09:05 -0500
Chuck Ritola <cjritola@xxxxxxxxx> escreveu:

> 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.
>
> Signed-off-by: Chuck Ritola <cjritola@xxxxxxxxx>
> ---
> drivers/media/dvb-frontends/a8293.c | 147 +++++++++++++++++++++++++-
> drivers/media/dvb-frontends/a8293.h | 2 +
> drivers/media/usb/em28xx/em28xx-dvb.c | 3 +
> 3 files changed, 150 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/dvb-frontends/a8293.c b/drivers/media/dvb-frontends/a8293.c
> index 57f52c004..f86af43ee 100644
> --- a/drivers/media/dvb-frontends/a8293.c
> +++ b/drivers/media/dvb-frontends/a8293.c
> @@ -3,16 +3,139 @@
> * Allegro A8293 SEC driver
> *
> * Copyright (C) 2011 Antti Palosaari <crope@xxxxxx>
> + * Copyright (C) 2021 Chuck Ritola <cjritola@xxxxxxxxx>

We don't usually add copyrights on files authored by others, except
when the original author explicitly agree with that by sending his
Signed-off-by or Acked-by.

So, except if Antti agrees with that, please remove this change
from the patch. Your credits will still be there stored at the
git tree.

> */
>
> #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 +143,7 @@ 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 +185,24 @@ 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,
> const struct i2c_device_id *id)
> {
> @@ -78,6 +219,7 @@ 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);
> @@ -127,5 +269,6 @@ static struct i2c_driver a8293_driver = {
> module_i2c_driver(a8293_driver);
>
> MODULE_AUTHOR("Antti Palosaari <crope@xxxxxx>");
> +MODULE_AUTHOR("Chuck Ritola <cjritola@xxxxxxxxx>");

Same applies here.

> MODULE_DESCRIPTION("Allegro A8293 SEC driver");
> MODULE_LICENSE("GPL");
> diff --git a/drivers/media/dvb-frontends/a8293.h b/drivers/media/dvb-frontends/a8293.h
> index 8c09635ef..0a807c022 100644
> --- a/drivers/media/dvb-frontends/a8293.h
> +++ b/drivers/media/dvb-frontends/a8293.h
> @@ -18,9 +18,11 @@
> /**
> * 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 */
> diff --git a/drivers/media/usb/em28xx/em28xx-dvb.c b/drivers/media/usb/em28xx/em28xx-dvb.c
> index 471bd7466..859f4a33e 100644
> --- a/drivers/media/usb/em28xx/em28xx-dvb.c
> +++ b/drivers/media/usb/em28xx/em28xx-dvb.c
> @@ -1208,6 +1208,9 @@ 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);

Thanks,
Mauro

Next message: Andy Shevchenko: "Re: [PATCH v2 2/2] pinctrl: Propagate firmware node from a parent device"
Previous message: Sergey Shtylyov: "Re: [PATCH] arm64: dts: renesas: r8a77961: Add lvsd0 device node"
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