From: Guenter Roeck <linux@roeck-us.net>
To: Chu Lin <linchuyuan@google.com>
Cc: jdelvare@suse.com, robh+dt@kernel.org,
linux-hwmon@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 2/2] hwmon: pmbus: max20730: adjust the vout reading given voltage divider
Date: Tue, 6 Oct 2020 14:55:52 -0700 [thread overview]
Message-ID: <20201006215552.GA96934@roeck-us.net> (raw)
In-Reply-To: <20201004031445.2321090-3-linchuyuan@google.com>
On Sun, Oct 04, 2020 at 03:14:45AM +0000, Chu Lin wrote:
> Problem:
> We use voltage dividers so that the voltage presented at the voltage
> sense pins is confusing. We might need to convert these readings to more
> meaningful readings given the voltage divider.
>
> Solution:
> Read the voltage divider resistance from dts and convert the voltage
> reading to a more meaningful reading.
>
> Testing:
> max20730 with voltage divider
>
> Signed-off-by: Chu Lin <linchuyuan@google.com>
> Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Applied to hwmon-next.
> ---
> ChangeLog v1 -> v2
> hwmon: pmbus: max20730:
> - Don't do anything to the ret if an error is returned from pmbus_read_word
> - avoid overflow when doing multiplication
>
> ChangeLog v2 -> v3
> dt-bindings: hwmon: max20730:
> - Provide the binding documentation in yaml format
> hwmon: pmbus: max20730:
> - No change
>
> ChangeLog v3 -> v4
> dt-bindings: hwmon: max20730:
> - Fix highefficiency to high efficiency in description
> - Fix presents to present in vout-voltage-divider
> - Add additionalProperties: false
> hwmon: pmbus: max20730:
> - No change
>
> drivers/hwmon/pmbus/max20730.c | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/drivers/hwmon/pmbus/max20730.c b/drivers/hwmon/pmbus/max20730.c
> index a151a2b588a5..fbf2f1e6c969 100644
> --- a/drivers/hwmon/pmbus/max20730.c
> +++ b/drivers/hwmon/pmbus/max20730.c
> @@ -31,6 +31,7 @@ struct max20730_data {
> struct pmbus_driver_info info;
> struct mutex lock; /* Used to protect against parallel writes */
> u16 mfr_devset1;
> + u32 vout_voltage_divider[2];
> };
>
> #define to_max20730_data(x) container_of(x, struct max20730_data, info)
> @@ -114,6 +115,14 @@ static int max20730_read_word_data(struct i2c_client *client, int page,
> max_c = max_current[data->id][(data->mfr_devset1 >> 5) & 0x3];
> ret = val_to_direct(max_c, PSC_CURRENT_OUT, info);
> break;
> + case PMBUS_READ_VOUT:
> + ret = pmbus_read_word_data(client, page, phase, reg);
> + if (ret > 0 && data->vout_voltage_divider[0] && data->vout_voltage_divider[1]) {
> + u64 temp = DIV_ROUND_CLOSEST_ULL((u64)ret * data->vout_voltage_divider[1],
> + data->vout_voltage_divider[0]);
> + ret = clamp_val(temp, 0, 0xffff);
> + }
> + break;
> default:
> ret = -ENODATA;
> break;
> @@ -364,6 +373,15 @@ static int max20730_probe(struct i2c_client *client,
> data->id = chip_id;
> mutex_init(&data->lock);
> memcpy(&data->info, &max20730_info[chip_id], sizeof(data->info));
> + if (of_property_read_u32_array(client->dev.of_node, "vout-voltage-divider",
> + data->vout_voltage_divider,
> + ARRAY_SIZE(data->vout_voltage_divider)) != 0)
> + memset(data->vout_voltage_divider, 0, sizeof(data->vout_voltage_divider));
> + if (data->vout_voltage_divider[1] < data->vout_voltage_divider[0]) {
> + dev_err(dev,
> + "The total resistance of voltage divider is less than output resistance\n");
> + return -ENODEV;
> + }
>
> ret = i2c_smbus_read_word_data(client, MAX20730_MFR_DEVSET1);
> if (ret < 0)
prev parent reply other threads:[~2020-10-06 21:55 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-04 3:14 [PATCH v4 0/2] hwmon: pmbus: max20730: adjust the vout base on Chu Lin
2020-10-04 3:14 ` [PATCH v4 1/2] dt-bindings: hwmon: max20730: adding device tree doc for max20730 Chu Lin
2020-10-06 21:17 ` Rob Herring
2020-10-06 21:55 ` Guenter Roeck
2020-10-04 3:14 ` [PATCH v4 2/2] hwmon: pmbus: max20730: adjust the vout reading given voltage divider Chu Lin
2020-10-04 15:43 ` Guenter Roeck
2020-10-05 3:07 ` Chu Lin
2020-10-05 5:24 ` Guenter Roeck
2020-10-05 15:03 ` Guenter Roeck
2020-10-06 21:55 ` Guenter Roeck [this message]
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