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Message-Id: <20211231035326.6759-1-cjritola@gmail.com>
Date: Thu, 30 Dec 2021 22:53:27 -0500
From: Chuck Ritola <cjritola@...il.com>
To: crope@....fi
Cc: mchehab@...nel.org, linux-media@...r.kernel.org,
linux-kernel@...r.kernel.org, cjritola@...il.com
Subject: [PATCH v2] 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.
Copyright and authorship notices removed from previous patch version.
Signed-off-by: Chuck Ritola <cjritola@...il.com>
---
drivers/media/dvb-frontends/a8293.c | 145 +++++++++++++++++++++++++-
drivers/media/dvb-frontends/a8293.h | 2 +
drivers/media/usb/em28xx/em28xx-dvb.c | 3 +
3 files changed, 148 insertions(+), 2 deletions(-)
diff --git a/drivers/media/dvb-frontends/a8293.c b/drivers/media/dvb-frontends/a8293.c
index 57f52c004..ff032f286 100644
--- a/drivers/media/dvb-frontends/a8293.c
+++ b/drivers/media/dvb-frontends/a8293.c
@@ -7,12 +7,134 @@
#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, ®0, 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, ®0, 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, ®1, 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 +142,7 @@ 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 +184,24 @@ 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 +218,7 @@ 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);
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);
--
2.20.1
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