2022-09-07 02:02:25

by Alexandru Gagniuc

[permalink] [raw]
Subject: [PATCH v2 2/3] hwmon: (tps23861) reduce count of i2c transactions for port_status

When reading the 'port_status' debugfs entry, some I2C registers were
read more than once. This looks inefficient in an I2C trace.

To reduce I2C traffic, update tps23861_port_status_show() to only read
each register once. Indexing the port number from 0 instead of 1 also
allows simplifying things a bit.

Signed-off-by: Alexandru Gagniuc <[email protected]>
---
Changes since v1:
- Do not brag about negative line count in commit message
- Do not change port number in port_status output

drivers/hwmon/tps23861.c | 79 ++++++++++++----------------------------
1 file changed, 24 insertions(+), 55 deletions(-)

diff --git a/drivers/hwmon/tps23861.c b/drivers/hwmon/tps23861.c
index f7c59ff7ae8e..019009b71a90 100644
--- a/drivers/hwmon/tps23861.c
+++ b/drivers/hwmon/tps23861.c
@@ -372,29 +372,12 @@ static const struct hwmon_chip_info tps23861_chip_info = {
.info = tps23861_info,
};

-static char *tps23861_port_operating_mode(struct tps23861_data *data, int port)
+static char *port_operating_mode_string(uint8_t mode_reg, unsigned int port)
{
- unsigned int regval;
- int mode;
+ unsigned int mode = ~0;

- regmap_read(data->regmap, OPERATING_MODE, &regval);
-
- switch (port) {
- case 1:
- mode = FIELD_GET(OPERATING_MODE_PORT_1_MASK, regval);
- break;
- case 2:
- mode = FIELD_GET(OPERATING_MODE_PORT_2_MASK, regval);
- break;
- case 3:
- mode = FIELD_GET(OPERATING_MODE_PORT_3_MASK, regval);
- break;
- case 4:
- mode = FIELD_GET(OPERATING_MODE_PORT_4_MASK, regval);
- break;
- default:
- mode = -EINVAL;
- }
+ if (port < TPS23861_NUM_PORTS)
+ mode = (mode_reg >> (2 * port)) & OPERATING_MODE_PORT_1_MASK;

switch (mode) {
case OPERATING_MODE_OFF:
@@ -410,15 +393,9 @@ static char *tps23861_port_operating_mode(struct tps23861_data *data, int port)
}
}

-static char *tps23861_port_detect_status(struct tps23861_data *data, int port)
+static char *port_detect_status_string(uint8_t status_reg)
{
- unsigned int regval;
-
- regmap_read(data->regmap,
- PORT_1_STATUS + (port - 1),
- &regval);
-
- switch (FIELD_GET(PORT_STATUS_DETECT_MASK, regval)) {
+ switch (FIELD_GET(PORT_STATUS_DETECT_MASK, status_reg)) {
case PORT_DETECT_UNKNOWN:
return "Unknown device";
case PORT_DETECT_SHORT:
@@ -448,15 +425,9 @@ static char *tps23861_port_detect_status(struct tps23861_data *data, int port)
}
}

-static char *tps23861_port_class_status(struct tps23861_data *data, int port)
+static char *port_class_status_string(uint8_t status_reg)
{
- unsigned int regval;
-
- regmap_read(data->regmap,
- PORT_1_STATUS + (port - 1),
- &regval);
-
- switch (FIELD_GET(PORT_STATUS_CLASS_MASK, regval)) {
+ switch (FIELD_GET(PORT_STATUS_CLASS_MASK, status_reg)) {
case PORT_CLASS_UNKNOWN:
return "Unknown";
case PORT_CLASS_RESERVED:
@@ -479,16 +450,9 @@ static char *tps23861_port_class_status(struct tps23861_data *data, int port)
}
}

-static char *tps23861_port_poe_plus_status(struct tps23861_data *data, int port)
+static char *port_poe_plus_status_string(uint8_t poe_plus, unsigned int port)
{
- unsigned int regval;
-
- regmap_read(data->regmap, POE_PLUS, &regval);
-
- if (BIT(port + 3) & regval)
- return "Yes";
- else
- return "No";
+ return (BIT(port + 4) & poe_plus) ? "Yes" : "No";
}

static int tps23861_port_resistance(struct tps23861_data *data, int port)
@@ -497,7 +461,7 @@ static int tps23861_port_resistance(struct tps23861_data *data, int port)
__le16 regval;

regmap_bulk_read(data->regmap,
- PORT_1_RESISTANCE_LSB + PORT_N_RESISTANCE_LSB_OFFSET * (port - 1),
+ PORT_1_RESISTANCE_LSB + PORT_N_RESISTANCE_LSB_OFFSET * port,
&regval,
2);

@@ -517,14 +481,19 @@ static int tps23861_port_resistance(struct tps23861_data *data, int port)
static int tps23861_port_status_show(struct seq_file *s, void *data)
{
struct tps23861_data *priv = s->private;
- int i;
-
- for (i = 1; i < TPS23861_NUM_PORTS + 1; i++) {
- seq_printf(s, "Port: \t\t%d\n", i);
- seq_printf(s, "Operating mode: %s\n", tps23861_port_operating_mode(priv, i));
- seq_printf(s, "Detected: \t%s\n", tps23861_port_detect_status(priv, i));
- seq_printf(s, "Class: \t\t%s\n", tps23861_port_class_status(priv, i));
- seq_printf(s, "PoE Plus: \t%s\n", tps23861_port_poe_plus_status(priv, i));
+ unsigned int i, mode, poe_plus, status;
+
+ regmap_read(priv->regmap, OPERATING_MODE, &mode);
+ regmap_read(priv->regmap, POE_PLUS, &poe_plus);
+
+ for (i = 0; i < TPS23861_NUM_PORTS; i++) {
+ regmap_read(priv->regmap, PORT_1_STATUS + i, &status);
+
+ seq_printf(s, "Port: \t\t%d\n", i + 1);
+ seq_printf(s, "Operating mode: %s\n", port_operating_mode_string(mode, i));
+ seq_printf(s, "Detected: \t%s\n", port_detect_status_string(status));
+ seq_printf(s, "Class: \t\t%s\n", port_class_status_string(status));
+ seq_printf(s, "PoE Plus: \t%s\n", port_poe_plus_status_string(poe_plus, i));
seq_printf(s, "Resistance: \t%d\n", tps23861_port_resistance(priv, i));
seq_putc(s, '\n');
}
--
2.34.3


2022-09-07 02:27:18

by Alexandru Gagniuc

[permalink] [raw]
Subject: [PATCH v2 3/3] hwmon: (tps23861) create unique debugfs directory per device

On systems with more than one tps23861, creating the debugfs directory
for additional devices fails with

debugfs: Directory 'tps23861' with parent '/' already present!

To resolve this, include the hwmon device name in the directory name.
Since the name is unique, this guarantees that the debugfs directory
is unique.

Signed-off-by: Alexandru Gagniuc <[email protected]>
Reviewed-by: Guenter Roeck <[email protected]>
---
drivers/hwmon/tps23861.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/hwmon/tps23861.c b/drivers/hwmon/tps23861.c
index 019009b71a90..a3d7d6b75a26 100644
--- a/drivers/hwmon/tps23861.c
+++ b/drivers/hwmon/tps23861.c
@@ -503,9 +503,17 @@ static int tps23861_port_status_show(struct seq_file *s, void *data)

DEFINE_SHOW_ATTRIBUTE(tps23861_port_status);

-static void tps23861_init_debugfs(struct tps23861_data *data)
+static void tps23861_init_debugfs(struct tps23861_data *data,
+ struct device *hwmon_dev)
{
- data->debugfs_dir = debugfs_create_dir(data->client->name, NULL);
+ const char *debugfs_name;
+
+ debugfs_name = devm_kasprintf(&data->client->dev, GFP_KERNEL, "%s-%s",
+ data->client->name, dev_name(hwmon_dev));
+ if (!debugfs_name)
+ return;
+
+ data->debugfs_dir = debugfs_create_dir(debugfs_name, NULL);

debugfs_create_file("port_status",
0400,
@@ -554,7 +562,7 @@ static int tps23861_probe(struct i2c_client *client)
if (IS_ERR(hwmon_dev))
return PTR_ERR(hwmon_dev);

- tps23861_init_debugfs(data);
+ tps23861_init_debugfs(data, hwmon_dev);

return 0;
}
--
2.34.3

2022-09-08 19:03:46

by Guenter Roeck

[permalink] [raw]
Subject: Re: [PATCH v2 3/3] hwmon: (tps23861) create unique debugfs directory per device

On Tue, Sep 06, 2022 at 08:54:05PM -0500, Alexandru Gagniuc wrote:
> On systems with more than one tps23861, creating the debugfs directory
> for additional devices fails with
>
> debugfs: Directory 'tps23861' with parent '/' already present!
>
> To resolve this, include the hwmon device name in the directory name.
> Since the name is unique, this guarantees that the debugfs directory
> is unique.
>
> Signed-off-by: Alexandru Gagniuc <[email protected]>
> Reviewed-by: Guenter Roeck <[email protected]>

Applied to hwmon-next.

Thanks,
Guenter

> ---
> drivers/hwmon/tps23861.c | 14 +++++++++++---
> 1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/hwmon/tps23861.c b/drivers/hwmon/tps23861.c
> index 019009b71a90..a3d7d6b75a26 100644
> --- a/drivers/hwmon/tps23861.c
> +++ b/drivers/hwmon/tps23861.c
> @@ -503,9 +503,17 @@ static int tps23861_port_status_show(struct seq_file *s, void *data)
>
> DEFINE_SHOW_ATTRIBUTE(tps23861_port_status);
>
> -static void tps23861_init_debugfs(struct tps23861_data *data)
> +static void tps23861_init_debugfs(struct tps23861_data *data,
> + struct device *hwmon_dev)
> {
> - data->debugfs_dir = debugfs_create_dir(data->client->name, NULL);
> + const char *debugfs_name;
> +
> + debugfs_name = devm_kasprintf(&data->client->dev, GFP_KERNEL, "%s-%s",
> + data->client->name, dev_name(hwmon_dev));
> + if (!debugfs_name)
> + return;
> +
> + data->debugfs_dir = debugfs_create_dir(debugfs_name, NULL);
>
> debugfs_create_file("port_status",
> 0400,
> @@ -554,7 +562,7 @@ static int tps23861_probe(struct i2c_client *client)
> if (IS_ERR(hwmon_dev))
> return PTR_ERR(hwmon_dev);
>
> - tps23861_init_debugfs(data);
> + tps23861_init_debugfs(data, hwmon_dev);
>
> return 0;
> }

2022-09-08 19:35:51

by Guenter Roeck

[permalink] [raw]
Subject: Re: [PATCH v2 2/3] hwmon: (tps23861) reduce count of i2c transactions for port_status

On Tue, Sep 06, 2022 at 08:54:04PM -0500, Alexandru Gagniuc wrote:
> When reading the 'port_status' debugfs entry, some I2C registers were
> read more than once. This looks inefficient in an I2C trace.
>
> To reduce I2C traffic, update tps23861_port_status_show() to only read
> each register once. Indexing the port number from 0 instead of 1 also
> allows simplifying things a bit.
>
> Signed-off-by: Alexandru Gagniuc <[email protected]>

Applied to hwmon-next.

Thanks,
Guenter