Re: [PATCH v2 2/3] lm25066: support SAMPLES_FOR_AVG register

["Adamski, Krzysztof (Nokia - PL/Wroclaw)" <krzysztof.adamski@nokia.com>]

On Sun, Apr 14, 2019 at 07:37:35AM -0700, Guenter Roeck wrote:
>On 4/13/19 9:03 AM, Adamski, Krzysztof (Nokia - PL/Wroclaw) wrote:
>>Manufacturer specific SAMPLES_FOR_AVG register allows setting the number
>>of samples used in computing the average values (PMBUS_VIRT_READ_*_AVG).
>>The number we write is an exponent of base 2 of the number of samples so
>>for example writing 3 will result in 8 samples average.
>>
>>Signed-off-by: Krzysztof Adamski <krzysztof.adamski@nokia.com>
>>---
>>  drivers/hwmon/pmbus/lm25066.c | 15 ++++++++++++++-
>>  1 file changed, 14 insertions(+), 1 deletion(-)
>>
>>diff --git a/drivers/hwmon/pmbus/lm25066.c b/drivers/hwmon/pmbus/lm25066.c
>>index 53db78753a0d..b560d33db459 100644
>>--- a/drivers/hwmon/pmbus/lm25066.c
>>+++ b/drivers/hwmon/pmbus/lm25066.c
>>@@ -26,6 +26,7 @@
>>  #include <linux/err.h>
>>  #include <linux/slab.h>
>>  #include <linux/i2c.h>
>>+#include <linux/log2.h>
>>  #include "pmbus.h"
>>  enum chips { lm25056, lm25066, lm5064, lm5066, lm5066i };
>>@@ -39,12 +40,15 @@ enum chips { lm25056, lm25066, lm5064, lm5066, lm5066i };
>>  #define LM25066_CLEAR_PIN_PEAK		0xd6
>>  #define LM25066_DEVICE_SETUP		0xd9
>>  #define LM25066_READ_AVG_VIN		0xdc
>>+#define LM25066_SAMPLES_FOR_AVG		0xdb
>>  #define LM25066_READ_AVG_VOUT		0xdd
>>  #define LM25066_READ_AVG_IIN		0xde
>>  #define LM25066_READ_AVG_PIN		0xdf
>>  #define LM25066_DEV_SETUP_CL		BIT(4)	/* Current limit */
>>+#define LM25066_SAMPLES_FOR_AVG_MAX	4096
>>+
>>  /* LM25056 only */
>>  #define LM25056_VAUX_OV_WARN_LIMIT	0xe3
>>@@ -284,6 +288,10 @@ static int lm25066_read_word_data(struct i2c_client *client, int page, int reg)
>>  	case PMBUS_VIRT_RESET_PIN_HISTORY:
>>  		ret = 0;
>>  		break;
>>+	case PMBUS_VIRT_SAMPLES:
>>+		ret = pmbus_read_byte_data(client, 0, LM25066_SAMPLES_FOR_AVG);
>
>		if (ret < 0)
>			return ret;
>

Good point. However the convention for this switch is to break instead
of returning early. I would stick with that if you don't mind.

>>+		ret = 1 << ret;
>>+		break;
>>  	default:
>>  		ret = -ENODATA;
>>  		break;
>>@@ -398,6 +406,11 @@ static int lm25066_write_word_data(struct i2c_client *client, int page, int reg,
>>  	case PMBUS_VIRT_RESET_PIN_HISTORY:
>>  		ret = pmbus_write_byte(client, 0, LM25066_CLEAR_PIN_PEAK);
>>  		break;
>>+	case PMBUS_VIRT_SAMPLES:
>>+		word = clamp_val(word, 0, LM25066_SAMPLES_FOR_AVG_MAX);
>
>0 is not valid, and ilog2(0) returns -1 (or is undefined).

True, I'll clamp with minimum 1 to fix that. I don't think it's worth
returning an error for 0. Do you?

>
>>+		ret = pmbus_write_byte_data(client, 0, LM25066_SAMPLES_FOR_AVG,
>>+					    ilog2(word));
>>+		break;
>>  	default:
>>  		ret = -ENODATA;
>>  		break;
>>@@ -438,7 +451,7 @@ static int lm25066_probe(struct i2c_client *client,
>>  	info->func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VMON
>>  	  | PMBUS_HAVE_PIN | PMBUS_HAVE_IIN | PMBUS_HAVE_STATUS_INPUT
>>-	  | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP;
>>+	  | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP | PMBUS_HAVE_SAMPLES;
>>  	if (data->id == lm25056) {
>>  		info->func[0] |= PMBUS_HAVE_STATUS_VMON;
>>
>

Krzysztof