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hwmon: (pmbus) Introduce page_change_delay

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We have some buggy pmbus devices that require a delay after performing a
page change operation before trying to issue more commands to the
device.

This allows for a configurable delay after page changes, but not
affecting other read or write operations.

This makes a slight behavioral tweak to the existing delay logic, where
it considers the longest of delays between operations, instead of always
chosing the write delay over the access delay.

Signed-off-by: William A. Kennington III <william@wkennington.com>
Link: https://lore.kernel.org/r/20250407201002.1198092-1-william@wkennington.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
William A. Kennington III
2025-04-07 13:10:02 -07:00
committed by Guenter Roeck
parent 2c183963fb
commit 73e5b6b51f
2 changed files with 36 additions and 34 deletions
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1
drivers/hwmon/pmbus/pmbus.h
View File

@@ -482,6 +482,7 @@ struct pmbus_driver_info {
*/
int access_delay; /* in microseconds */
int write_delay; /* in microseconds */
int page_change_delay; /* in microseconds */
};
/* Regulator ops */

69
drivers/hwmon/pmbus/pmbus_core.c
View File

@@ -32,6 +32,13 @@
#define PMBUS_ATTR_ALLOC_SIZE 32
#define PMBUS_NAME_SIZE 24
/*
* The type of operation used for picking the delay between
* successive pmbus operations.
*/
#define PMBUS_OP_WRITE BIT(0)
#define PMBUS_OP_PAGE_CHANGE BIT(1)
static int wp = -1;
module_param(wp, int, 0444);
@@ -113,8 +120,8 @@ struct pmbus_data {
int vout_low[PMBUS_PAGES]; /* voltage low margin */
int vout_high[PMBUS_PAGES]; /* voltage high margin */
ktime_t write_time; /* Last SMBUS write timestamp */
ktime_t access_time; /* Last SMBUS access timestamp */
ktime_t next_access_backoff; /* Wait until at least this time */
};
struct pmbus_debugfs_entry {
@@ -169,32 +176,26 @@ EXPORT_SYMBOL_NS_GPL(pmbus_set_update, "PMBUS");
static void pmbus_wait(struct i2c_client *client)
{
struct pmbus_data *data = i2c_get_clientdata(client);
const struct pmbus_driver_info *info = data->info;
s64 delta;
s64 delay = ktime_us_delta(data->next_access_backoff, ktime_get());
if (info->access_delay) {
delta = ktime_us_delta(ktime_get(), data->access_time);
if (delta < info->access_delay)
fsleep(info->access_delay - delta);
} else if (info->write_delay) {
delta = ktime_us_delta(ktime_get(), data->write_time);
if (delta < info->write_delay)
fsleep(info->write_delay - delta);
}
if (delay > 0)
fsleep(delay);
}
/* Sets the last accessed timestamp for pmbus_wait */
static void pmbus_update_ts(struct i2c_client *client, bool write_op)
/* Sets the last operation timestamp for pmbus_wait */
static void pmbus_update_ts(struct i2c_client *client, int op)
{
struct pmbus_data *data = i2c_get_clientdata(client);
const struct pmbus_driver_info *info = data->info;
int delay = info->access_delay;
if (info->access_delay)
data->access_time = ktime_get();
else if (info->write_delay && write_op)
data->write_time = ktime_get();
if (op & PMBUS_OP_WRITE)
delay = max(delay, info->write_delay);
if (op & PMBUS_OP_PAGE_CHANGE)
delay = max(delay, info->page_change_delay);
if (delay > 0)
data->next_access_backoff = ktime_add_us(ktime_get(), delay);
}
int pmbus_set_page(struct i2c_client *client, int page, int phase)
@@ -209,13 +210,13 @@ int pmbus_set_page(struct i2c_client *client, int page, int phase)
data->info->pages > 1 && page != data->currpage) {
pmbus_wait(client);
rv = i2c_smbus_write_byte_data(client, PMBUS_PAGE, page);
pmbus_update_ts(client, true);
pmbus_update_ts(client, PMBUS_OP_WRITE | PMBUS_OP_PAGE_CHANGE);
if (rv < 0)
return rv;
pmbus_wait(client);
rv = i2c_smbus_read_byte_data(client, PMBUS_PAGE);
pmbus_update_ts(client, false);
pmbus_update_ts(client, 0);
if (rv < 0)
return rv;
@@ -229,7 +230,7 @@ int pmbus_set_page(struct i2c_client *client, int page, int phase)
pmbus_wait(client);
rv = i2c_smbus_write_byte_data(client, PMBUS_PHASE,
phase);
pmbus_update_ts(client, true);
pmbus_update_ts(client, PMBUS_OP_WRITE);
if (rv)
return rv;
}
@@ -249,7 +250,7 @@ int pmbus_write_byte(struct i2c_client *client, int page, u8 value)
pmbus_wait(client);
rv = i2c_smbus_write_byte(client, value);
pmbus_update_ts(client, true);
pmbus_update_ts(client, PMBUS_OP_WRITE);
return rv;
}
@@ -284,7 +285,7 @@ int pmbus_write_word_data(struct i2c_client *client, int page, u8 reg,
pmbus_wait(client);
rv = i2c_smbus_write_word_data(client, reg, word);
pmbus_update_ts(client, true);
pmbus_update_ts(client, PMBUS_OP_WRITE);
return rv;
}
@@ -405,7 +406,7 @@ int pmbus_read_word_data(struct i2c_client *client, int page, int phase, u8 reg)
pmbus_wait(client);
rv = i2c_smbus_read_word_data(client, reg);
pmbus_update_ts(client, false);
pmbus_update_ts(client, 0);
return rv;
}
@@ -468,7 +469,7 @@ int pmbus_read_byte_data(struct i2c_client *client, int page, u8 reg)
pmbus_wait(client);
rv = i2c_smbus_read_byte_data(client, reg);
pmbus_update_ts(client, false);
pmbus_update_ts(client, 0);
return rv;
}
@@ -484,7 +485,7 @@ int pmbus_write_byte_data(struct i2c_client *client, int page, u8 reg, u8 value)
pmbus_wait(client);
rv = i2c_smbus_write_byte_data(client, reg, value);
pmbus_update_ts(client, true);
pmbus_update_ts(client, PMBUS_OP_WRITE);
return rv;
}
@@ -520,7 +521,7 @@ static int pmbus_read_block_data(struct i2c_client *client, int page, u8 reg,
pmbus_wait(client);
rv = i2c_smbus_read_block_data(client, reg, data_buf);
pmbus_update_ts(client, false);
pmbus_update_ts(client, 0);
return rv;
}
@@ -2524,7 +2525,7 @@ static int pmbus_read_coefficients(struct i2c_client *client,
rv = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
I2C_SMBUS_WRITE, PMBUS_COEFFICIENTS,
I2C_SMBUS_BLOCK_PROC_CALL, &data);
pmbus_update_ts(client, true);
pmbus_update_ts(client, PMBUS_OP_WRITE);
if (rv < 0)
return rv;
@@ -2728,7 +2729,7 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
if (!(data->flags & PMBUS_NO_CAPABILITY)) {
pmbus_wait(client);
ret = i2c_smbus_read_byte_data(client, PMBUS_CAPABILITY);
pmbus_update_ts(client, false);
pmbus_update_ts(client, 0);
if (ret >= 0 && (ret & PB_CAPABILITY_ERROR_CHECK)) {
if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_PEC))
@@ -2744,13 +2745,13 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
data->read_status = pmbus_read_status_word;
pmbus_wait(client);
ret = i2c_smbus_read_word_data(client, PMBUS_STATUS_WORD);
pmbus_update_ts(client, false);
pmbus_update_ts(client, 0);
if (ret < 0 || ret == 0xffff) {
data->read_status = pmbus_read_status_byte;
pmbus_wait(client);
ret = i2c_smbus_read_byte_data(client, PMBUS_STATUS_BYTE);
pmbus_update_ts(client, false);
pmbus_update_ts(client, 0);
if (ret < 0 || ret == 0xff) {
dev_err(dev, "PMBus status register not found\n");