From: Balakrishna Godavarthi <bgodavar@xxxxxxxxxxxxxx>
Add support to set voltage/current of various regulators
to power up/down Bluetooth chip wcn3990.
Signed-off-by: Balakrishna Godavarthi <bgodavar@xxxxxxxxxxxxxx>
---
Changes in v11:
* removed support to read regulator currents from dts.
* updated review comments.
Changes in v10:
* added support to read regulator currents from dts.
* added support to try to connect with chip if it fails to respond to initial commands
* updated review comments.
changes in v9:
* moved flow control to vendor and set_baudarte functions.
* removed parent regs.
changes in v8:
* closing qca buffer, if qca_power_setup fails
* chnaged ibs start timer function call location.
* updated review comments.
changes in v7:
* addressed review comments.
changes in v6:
* Hooked up qca_power to qca_serdev.
* renamed all the naming inconsistency functions with qca_*
* leveraged common code of ROME for wcn3990.
* created wrapper functions for re-usable blocks.
* updated function of _*regulator_enable and _*regualtor_disable.
* removed redundant comments and functions.
* addressed review comments.
Changes in v5:
* updated regulator vddpa min_uV to 1304000.
* addressed review comments.
Changes in v4:
* Segregated the changes of btqca from hci_qca
* rebased all changes on top of bluetooth-next.
* addressed review comments.
---
drivers/bluetooth/btqca.h | 3 +
drivers/bluetooth/hci_qca.c | 424 ++++++++++++++++++++++++++++++++----
2 files changed, 380 insertions(+), 47 deletions(-)
diff --git a/drivers/bluetooth/btqca.h b/drivers/bluetooth/btqca.h
index a9c2779f3e07..0c01f375fe83 100644
--- a/drivers/bluetooth/btqca.h
+++ b/drivers/bluetooth/btqca.h
@@ -37,6 +37,9 @@
#define EDL_TAG_ID_HCI (17)
#define EDL_TAG_ID_DEEP_SLEEP (27)
+#define QCA_WCN3990_POWERON_PULSE 0xFC
+#define QCA_WCN3990_POWEROFF_PULSE 0xC0
+
enum qca_bardrate {
QCA_BAUDRATE_115200 = 0,
QCA_BAUDRATE_57600,
diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
index a6e7d38ef931..66e7930436d5 100644
--- a/drivers/bluetooth/hci_qca.c
+++ b/drivers/bluetooth/hci_qca.c
@@ -5,7 +5,7 @@
* protocol extension to H4.
*
* Copyright (C) 2007 Texas Instruments, Inc.
- * Copyright (c) 2010, 2012 The Linux Foundation. All rights reserved.
+ * Copyright (c) 2010, 2012, 2018 The Linux Foundation. All rights reserved.
*
* Acknowledgements:
* This file is based on hci_ll.c, which was...
@@ -31,9 +31,14 @@
#include <linux/kernel.h>
#include <linux/clk.h>
#include <linux/debugfs.h>
+#include <linux/delay.h>
+#include <linux/device.h>
#include <linux/gpio/consumer.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
#include <linux/serdev.h>
#include <net/bluetooth/bluetooth.h>
@@ -124,12 +129,46 @@ enum qca_speed_type {
QCA_OPER_SPEED
};
+/*
+ * Voltage regulator information required for configuring the
+ * QCA Bluetooth chipset
+ */
+struct qca_vreg {
+ const char *name;
+ unsigned int min_uV;
+ unsigned int max_uV;
+ unsigned int load_uA;
+};
+
+struct qca_vreg_data {
+ enum qca_btsoc_type soc_type;
+ struct qca_vreg *vregs;
+ size_t num_vregs;
+};
+
+/*
+ * Platform data for the QCA Bluetooth power driver.
+ */
+struct qca_power {
+ struct device *dev;
+ const struct qca_vreg_data *vreg_data;
+ struct regulator_bulk_data *vreg_bulk;
+ bool vregs_on;
+};
+
struct qca_serdev {
struct hci_uart serdev_hu;
struct gpio_desc *bt_en;
struct clk *susclk;
+ enum qca_btsoc_type btsoc_type;
+ struct qca_power *bt_power;
+ u32 init_speed;
+ u32 oper_speed;
};
+static int qca_power_setup(struct hci_uart *hu, bool on);
+static void qca_power_shutdown(struct hci_dev *hdev);
+
static void __serial_clock_on(struct tty_struct *tty)
{
/* TODO: Some chipset requires to enable UART clock on client
@@ -407,6 +446,7 @@ static int qca_open(struct hci_uart *hu)
{
struct qca_serdev *qcadev;
struct qca_data *qca;
+ int ret;
BT_DBG("hu %p qca_open", hu);
@@ -458,19 +498,32 @@ static int qca_open(struct hci_uart *hu)
hu->priv = qca;
- timer_setup(&qca->wake_retrans_timer, hci_ibs_wake_retrans_timeout, 0);
- qca->wake_retrans = IBS_WAKE_RETRANS_TIMEOUT_MS;
-
- timer_setup(&qca->tx_idle_timer, hci_ibs_tx_idle_timeout, 0);
- qca->tx_idle_delay = IBS_TX_IDLE_TIMEOUT_MS;
-
if (hu->serdev) {
serdev_device_open(hu->serdev);
qcadev = serdev_device_get_drvdata(hu->serdev);
- gpiod_set_value_cansleep(qcadev->bt_en, 1);
+ if (qcadev->btsoc_type != QCA_WCN3990) {
+ gpiod_set_value_cansleep(qcadev->bt_en, 1);
+ } else {
+ hu->init_speed = qcadev->init_speed;
+ hu->oper_speed = qcadev->oper_speed;
+ ret = qca_power_setup(hu, true);
+ if (ret) {
+ destroy_workqueue(qca->workqueue);
+ kfree_skb(qca->rx_skb);
+ hu->priv = NULL;
+ kfree(qca);
+ return ret;
+ }
+ }
}
+ timer_setup(&qca->wake_retrans_timer, hci_ibs_wake_retrans_timeout, 0);
+ qca->wake_retrans = IBS_WAKE_RETRANS_TIMEOUT_MS;
+
+ timer_setup(&qca->tx_idle_timer, hci_ibs_tx_idle_timeout, 0);
+ qca->tx_idle_delay = IBS_TX_IDLE_TIMEOUT_MS;
+
BT_DBG("HCI_UART_QCA open, tx_idle_delay=%u, wake_retrans=%u",
qca->tx_idle_delay, qca->wake_retrans);
@@ -554,10 +607,13 @@ static int qca_close(struct hci_uart *hu)
qca->hu = NULL;
if (hu->serdev) {
- serdev_device_close(hu->serdev);
-
qcadev = serdev_device_get_drvdata(hu->serdev);
- gpiod_set_value_cansleep(qcadev->bt_en, 0);
+ if (qcadev->btsoc_type == QCA_WCN3990)
+ qca_power_shutdown(hu->hdev);
+ else
+ gpiod_set_value_cansleep(qcadev->bt_en, 0);
+
+ serdev_device_close(hu->serdev);
}
kfree_skb(qca->rx_skb);
@@ -891,6 +947,7 @@ static int qca_set_baudrate(struct hci_dev *hdev, uint8_t baudrate)
struct hci_uart *hu = hci_get_drvdata(hdev);
struct qca_data *qca = hu->priv;
struct sk_buff *skb;
+ struct qca_serdev *qcadev;
u8 cmd[] = { 0x01, 0x48, 0xFC, 0x01, 0x00 };
if (baudrate > QCA_BAUDRATE_3200000)
@@ -904,6 +961,13 @@ static int qca_set_baudrate(struct hci_dev *hdev, uint8_t baudrate)
return -ENOMEM;
}
+ /* Disabling hardware flow control is mandatory while
+ * sending change baudrate request to wcn3990 SoC.
+ */
+ qcadev = serdev_device_get_drvdata(hu->serdev);
+ if (qcadev->btsoc_type == QCA_WCN3990)
+ hci_uart_set_flow_control(hu, true);
+
/* Assign commands to change baudrate and packet type. */
skb_put_data(skb, cmd, sizeof(cmd));
hci_skb_pkt_type(skb) = HCI_COMMAND_PKT;
@@ -919,6 +983,9 @@ static int qca_set_baudrate(struct hci_dev *hdev, uint8_t baudrate)
schedule_timeout(msecs_to_jiffies(BAUDRATE_SETTLE_TIMEOUT_MS));
set_current_state(TASK_RUNNING);
+ if (qcadev->btsoc_type == QCA_WCN3990)
+ hci_uart_set_flow_control(hu, false);
+
return 0;
}
@@ -930,6 +997,43 @@ static inline void host_set_baudrate(struct hci_uart *hu, unsigned int speed)
hci_uart_set_baudrate(hu, speed);
}
+static int qca_send_power_pulse(struct hci_dev *hdev, u8 cmd)
+{
+ struct hci_uart *hu = hci_get_drvdata(hdev);
+ struct qca_data *qca = hu->priv;
+ struct sk_buff *skb;
+
+ /* These power pulses are single byte command which are sent
+ * at required baudrate to wcn3990. On wcn3990, we have an external
+ * circuit at Tx pin which decodes the pulse sent at specific baudrate.
+ * For example, wcn3990 supports RF COEX antenna for both Wi-Fi/BT
+ * and also we use the same power inputs to turn on and off for
+ * Wi-Fi/BT. Powering up the power sources will not enable BT, until
+ * we send a power on pulse at 115200 bps. This algorithm will help to
+ * save power. Disabling hardware flow control is mandatory while
+ * sending power pulses to SoC.
+ */
+ bt_dev_dbg(hdev, "sending power pulse %02x to SoC", cmd);
+
+ skb = bt_skb_alloc(sizeof(cmd), GFP_KERNEL);
+ if (!skb)
+ return -ENOMEM;
+
+ hci_uart_set_flow_control(hu, true);
+
+ skb_put_u8(skb, cmd);
+ hci_skb_pkt_type(skb) = HCI_COMMAND_PKT;
+
+ skb_queue_tail(&qca->txq, skb);
+ hci_uart_tx_wakeup(hu);
+
+ /* Wait for 100 uS for SoC to settle down */
+ usleep_range(100, 200);
+ hci_uart_set_flow_control(hu, false);
+
+ return 0;
+}
+
static unsigned int qca_get_speed(struct hci_uart *hu,
enum qca_speed_type speed_type)
{
@@ -952,9 +1056,18 @@ static unsigned int qca_get_speed(struct hci_uart *hu,
static int qca_check_speeds(struct hci_uart *hu)
{
- if (!qca_get_speed(hu, QCA_INIT_SPEED) ||
- !qca_get_speed(hu, QCA_OPER_SPEED))
- return -EINVAL;
+ struct qca_serdev *qcadev;
+
+ qcadev = serdev_device_get_drvdata(hu->serdev);
+ if (qcadev->btsoc_type == QCA_WCN3990) {
+ if (!qca_get_speed(hu, QCA_INIT_SPEED) &&
+ !qca_get_speed(hu, QCA_OPER_SPEED))
+ return -EINVAL;
+ } else {
+ if (!qca_get_speed(hu, QCA_INIT_SPEED) ||
+ !qca_get_speed(hu, QCA_OPER_SPEED))
+ return -EINVAL;
+ }
return 0;
}
@@ -974,7 +1087,7 @@ static int qca_set_speed(struct hci_uart *hu, enum qca_speed_type speed_type)
return 0;
qca_baudrate = qca_get_baudrate_value(speed);
- bt_dev_info(hu->hdev, "Set UART speed to %d", speed);
+ bt_dev_dbg(hu->hdev, "Set UART speed to %d", speed);
ret = qca_set_baudrate(hu->hdev, qca_baudrate);
if (ret)
return ret;
@@ -985,15 +1098,73 @@ static int qca_set_speed(struct hci_uart *hu, enum qca_speed_type speed_type)
return 0;
}
+static int qca_wcn3990_init(struct hci_uart *hu, u32 *soc_ver)
+{
+ struct hci_dev *hdev = hu->hdev;
+ int i, ret;
+
+ /* wcn3990 is a discrete Bluetooth chip connected to SoC.
+ * sometimes we will face communication synchronization issues,
+ * like reading version command timeouts. In which HCI_SETUP fails,
+ * to overcome these issues, we try to communicate by performing an
+ * cold power off and on.
+ */
+ for (i = 0; i <= 3; i++) {
+ ret = qca_power_setup(hu, true);
+ if (ret)
+ goto regs_off;
+
+ /* Forcefully enable wcn3990 to enter in to boot mode. */
+ host_set_baudrate(hu, 2400);
+ ret = qca_send_power_pulse(hdev, QCA_WCN3990_POWEROFF_PULSE);
+ if (ret)
+ goto regs_off;
+
+ qca_set_speed(hu, QCA_INIT_SPEED);
+ ret = qca_send_power_pulse(hdev, QCA_WCN3990_POWERON_PULSE);
+ if (ret)
+ goto regs_off;
+
+ /* Wait for 100 ms for SoC to boot */
+ msleep(100);
+
+ /* Now the device is in ready state to communicate with host.
+ * To sync host with device we need to reopen port.
+ * Without this, we will have RTS and CTS synchronization
+ * issues.
+ */
+ serdev_device_close(hu->serdev);
+ ret = serdev_device_open(hu->serdev);
+ if (ret) {
+ bt_dev_err(hu->hdev, "failed to open port");
+ break;
+ }
+
+ hci_uart_set_flow_control(hu, false);
+ ret = qca_read_soc_version(hdev, soc_ver);
+
+ if (!ret)
+ break;
+
+regs_off:
+ bt_dev_err(hdev, "retrying to establish communication: %d",
+ i + 1);
+ qca_power_shutdown(hdev);
+ }
+
+ return ret;
+}
+
static int qca_setup(struct hci_uart *hu)
{
struct hci_dev *hdev = hu->hdev;
struct qca_data *qca = hu->priv;
unsigned int speed, qca_baudrate = QCA_BAUDRATE_115200;
+ struct qca_serdev *qcadev;
int ret;
int soc_ver = 0;
- bt_dev_info(hdev, "ROME setup");
+ qcadev = serdev_device_get_drvdata(hu->serdev);
ret = qca_check_speeds(hu);
if (ret)
@@ -1002,8 +1173,15 @@ static int qca_setup(struct hci_uart *hu)
/* Patch downloading has to be done without IBS mode */
clear_bit(STATE_IN_BAND_SLEEP_ENABLED, &qca->flags);
- /* Setup initial baudrate */
- qca_set_speed(hu, QCA_INIT_SPEED);
+ if (qcadev->btsoc_type == QCA_WCN3990) {
+ bt_dev_info(hdev, "setting up wcn3990");
+ ret = qca_wcn3990_init(hu, &soc_ver);
+ if (ret)
+ return ret;
+ } else {
+ bt_dev_info(hdev, "ROME setup");
+ qca_set_speed(hu, QCA_INIT_SPEED);
+ }
/* Setup user speed if needed */
speed = qca_get_speed(hu, QCA_OPER_SPEED);
@@ -1015,15 +1193,16 @@ static int qca_setup(struct hci_uart *hu)
qca_baudrate = qca_get_baudrate_value(speed);
}
- /* Get QCA version information */
- ret = qca_read_soc_version(hdev, &soc_ver);
- if (ret)
- return ret;
+ if (qcadev->btsoc_type != QCA_WCN3990) {
+ /* Get QCA version information */
+ ret = qca_read_soc_version(hdev, &soc_ver);
+ if (ret)
+ return ret;
+ }
bt_dev_info(hdev, "QCA controller version 0x%08x", soc_ver);
-
/* Setup patch / NVM configurations */
- ret = qca_uart_setup(hdev, qca_baudrate, QCA_ROME, soc_ver);
+ ret = qca_uart_setup(hdev, qca_baudrate, qcadev->btsoc_type, soc_ver);
if (!ret) {
set_bit(STATE_IN_BAND_SLEEP_ENABLED, &qca->flags);
qca_debugfs_init(hdev);
@@ -1059,9 +1238,123 @@ static struct hci_uart_proto qca_proto = {
.dequeue = qca_dequeue,
};
+static const struct qca_vreg_data qca_soc_data = {
+ .soc_type = QCA_WCN3990,
+ .vregs = (struct qca_vreg []) {
+ { "vddio", 1800000, 1900000, 15000 },
+ { "vddxo", 1800000, 1900000, 80000 },
+ { "vddrf", 1300000, 1350000, 300000 },
+ { "vddch0", 3300000, 3400000, 450000 },
+ },
+ .num_vregs = 4,
+};
+
+static void qca_power_shutdown(struct hci_dev *hdev)
+{
+ struct hci_uart *hu = hci_get_drvdata(hdev);
+
+ host_set_baudrate(hu, 2400);
+ qca_send_power_pulse(hdev, QCA_WCN3990_POWEROFF_PULSE);
+ qca_power_setup(hu, false);
+}
+
+static int qca_enable_regulator(struct qca_vreg vregs,
+ struct regulator *regulator)
+{
+ int ret;
+
+ ret = regulator_set_voltage(regulator, vregs.min_uV,
+ vregs.max_uV);
+ if (ret)
+ return ret;
+
+ if (vregs.load_uA)
+ ret = regulator_set_load(regulator,
+ vregs.load_uA);
+
+ if (ret)
+ return ret;
+
+ return regulator_enable(regulator);
+
+}
+
+static void qca_disable_regulator(struct qca_vreg vregs,
+ struct regulator *regulator)
+{
+ regulator_disable(regulator);
+ regulator_set_voltage(regulator, 0, vregs.max_uV);
+ if (vregs.load_uA)
+ regulator_set_load(regulator, 0);
+
+}
+
+static int qca_power_setup(struct hci_uart *hu, bool on)
+{
+ struct qca_vreg *vregs;
+ struct regulator_bulk_data *vreg_bulk;
+ struct qca_serdev *qcadev;
+ int i, num_vregs, ret = 0;
+
+ qcadev = serdev_device_get_drvdata(hu->serdev);
+ if (!qcadev || !qcadev->bt_power || !qcadev->bt_power->vreg_data ||
+ !qcadev->bt_power->vreg_bulk)
+ return -EINVAL;
+
+ vregs = qcadev->bt_power->vreg_data->vregs;
+ vreg_bulk = qcadev->bt_power->vreg_bulk;
+ num_vregs = qcadev->bt_power->vreg_data->num_vregs;
+ BT_DBG("on: %d", on);
+ if (on && !qcadev->bt_power->vregs_on) {
+ for (i = 0; i < num_vregs; i++) {
+ ret = qca_enable_regulator(vregs[i],
+ vreg_bulk[i].consumer);
+ if (ret)
+ break;
+ }
+
+ if (ret) {
+ BT_ERR("failed to enable regulator:%s", vregs[i].name);
+ /* turn off regulators which are enabled */
+ for (i = i - 1; i >= 0; i--)
+ qca_disable_regulator(vregs[i],
+ vreg_bulk[i].consumer);
+ } else {
+ qcadev->bt_power->vregs_on = true;
+ }
+ } else if (!on && qcadev->bt_power->vregs_on) {
+ /* turn off regulator in reverse order */
+ i = qcadev->bt_power->vreg_data->num_vregs - 1;
+ for ( ; i >= 0; i--)
+ qca_disable_regulator(vregs[i], vreg_bulk[i].consumer);
+
+ qcadev->bt_power->vregs_on = false;
+ }
+
+ return ret;
+}
+
+static int qca_init_regulators(struct qca_power *qca,
+ const struct qca_vreg *vregs, size_t num_vregs)
+{
+ int i;
+
+ qca->vreg_bulk = devm_kzalloc(qca->dev, num_vregs *
+ sizeof(struct regulator_bulk_data),
+ GFP_KERNEL);
+ if (!qca->vreg_bulk)
+ return -ENOMEM;
+
+ for (i = 0; i < num_vregs; i++)
+ qca->vreg_bulk[i].supply = vregs[i].name;
+
+ return devm_regulator_bulk_get(qca->dev, num_vregs, qca->vreg_bulk);
+}
+
static int qca_serdev_probe(struct serdev_device *serdev)
{
struct qca_serdev *qcadev;
+ const struct qca_vreg_data *data;
int err;
qcadev = devm_kzalloc(&serdev->dev, sizeof(*qcadev), GFP_KERNEL);
@@ -1069,47 +1362,84 @@ static int qca_serdev_probe(struct serdev_device *serdev)
return -ENOMEM;
qcadev->serdev_hu.serdev = serdev;
+ data = of_device_get_match_data(&serdev->dev);
serdev_device_set_drvdata(serdev, qcadev);
+ if (data && data->soc_type == QCA_WCN3990) {
+ qcadev->btsoc_type = QCA_WCN3990;
+ qcadev->bt_power = devm_kzalloc(&serdev->dev,
+ sizeof(struct qca_power),
+ GFP_KERNEL);
+ if (!qcadev->bt_power)
+ return -ENOMEM;
+
+ qcadev->bt_power->dev = &serdev->dev;
+ qcadev->bt_power->vreg_data = data;
+ err = qca_init_regulators(qcadev->bt_power, data->vregs,
+ data->num_vregs);
+ if (err) {
+ BT_ERR("Failed to init regulators:%d", err);
+ goto out;
+ }
- qcadev->bt_en = devm_gpiod_get(&serdev->dev, "enable",
- GPIOD_OUT_LOW);
- if (IS_ERR(qcadev->bt_en)) {
- dev_err(&serdev->dev, "failed to acquire enable gpio\n");
- return PTR_ERR(qcadev->bt_en);
- }
+ qcadev->bt_power->vregs_on = false;
- qcadev->susclk = devm_clk_get(&serdev->dev, NULL);
- if (IS_ERR(qcadev->susclk)) {
- dev_err(&serdev->dev, "failed to acquire clk\n");
- return PTR_ERR(qcadev->susclk);
- }
+ device_property_read_u32(&serdev->dev, "max-speed",
+ &qcadev->oper_speed);
+ if (!qcadev->oper_speed)
+ BT_DBG("UART will pick default operating speed");
- err = clk_set_rate(qcadev->susclk, SUSCLK_RATE_32KHZ);
- if (err)
- return err;
+ err = hci_uart_register_device(&qcadev->serdev_hu, &qca_proto);
+ if (err) {
+ BT_ERR("wcn3990 serdev registration failed");
+ goto out;
+ }
+ } else {
+ qcadev->btsoc_type = QCA_ROME;
+ qcadev->bt_en = devm_gpiod_get(&serdev->dev, "enable",
+ GPIOD_OUT_LOW);
+ if (IS_ERR(qcadev->bt_en)) {
+ dev_err(&serdev->dev, "failed to acquire enable gpio\n");
+ return PTR_ERR(qcadev->bt_en);
+ }
- err = clk_prepare_enable(qcadev->susclk);
- if (err)
- return err;
+ qcadev->susclk = devm_clk_get(&serdev->dev, NULL);
+ if (IS_ERR(qcadev->susclk)) {
+ dev_err(&serdev->dev, "failed to acquire clk\n");
+ return PTR_ERR(qcadev->susclk);
+ }
- err = hci_uart_register_device(&qcadev->serdev_hu, &qca_proto);
- if (err)
- clk_disable_unprepare(qcadev->susclk);
+ err = clk_set_rate(qcadev->susclk, SUSCLK_RATE_32KHZ);
+ if (err)
+ return err;
+
+ err = clk_prepare_enable(qcadev->susclk);
+ if (err)
+ return err;
+
+ err = hci_uart_register_device(&qcadev->serdev_hu, &qca_proto);
+ if (err)
+ clk_disable_unprepare(qcadev->susclk);
+ }
+
+out: return err;
- return err;
}
static void qca_serdev_remove(struct serdev_device *serdev)
{
struct qca_serdev *qcadev = serdev_device_get_drvdata(serdev);
- hci_uart_unregister_device(&qcadev->serdev_hu);
+ if (qcadev->btsoc_type == QCA_WCN3990)
+ qca_power_shutdown(qcadev->serdev_hu.hdev);
+ else
+ clk_disable_unprepare(qcadev->susclk);
- clk_disable_unprepare(qcadev->susclk);
+ hci_uart_unregister_device(&qcadev->serdev_hu);
}
static const struct of_device_id qca_bluetooth_of_match[] = {
{ .compatible = "qcom,qca6174-bt" },
+ { .compatible = "qcom,wcn3990-bt", .data = &qca_soc_data},
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, qca_bluetooth_of_match);
--
2.17.1
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
