Messages in this thread Patch in this message |  | | From | Guenter Roeck <> | Subject | Re: [PATCH v2 3/6] hwmon: (pmbus/pim4328) Add support for reading direct format coefficients | Date | Sat, 22 May 2021 06:41:31 -0700 |
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On 5/22/21 3:55 AM, Erik Rosen wrote: > Add support for reading and decoding direct format coefficients to > the PMBus core driver. If the new flag PMBUS_USE_COEFFICIENTS_CMD > is set, the driver will use the COEFFICIENTS register together with > the information in the pmbus_sensor_attr structs to initialize > relevant coefficients for the direct mode format. > > Signed-off-by: Erik Rosen <erik.rosen@metormote.com> > --- > drivers/hwmon/pmbus/pmbus_core.c | 93 ++++++++++++++++++++++++++++++++ > include/linux/pmbus.h | 8 +++ > 2 files changed, 101 insertions(+) > > diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c > index 460cbfd716e4..03c169bf5633 100644 > --- a/drivers/hwmon/pmbus/pmbus_core.c > +++ b/drivers/hwmon/pmbus/pmbus_core.c > @@ -2177,6 +2177,38 @@ static int pmbus_find_attributes(struct i2c_client *client, > return ret; > } > > +static int pmbus_init_coefficients(struct i2c_client *client, > + struct pmbus_data *data, int page,
This seems wrong. Coefficients are not maintained per page but per class, and (re-)reading them for each supported page doesn't really add value or even make sense.
> + enum pmbus_sensor_classes sensor_class, > + const struct pmbus_sensor_attr *attrs, > + int nattrs) > +{ > + int i, status; > + > + for (i = 0; i < nattrs; i++) { > + if (attrs->class == sensor_class && > + (attrs->func & data->info->func[page])) { > + status = pmbus_read_coefficients(client, > + (struct pmbus_driver_info *)data->info, > + sensor_class, > + attrs->reg); > + if (status < 0) { > + dev_err(&client->dev, > + "Failed to read coefficients for register: %x\n", > + attrs->reg); > + return status; > + } > + return 0; > + } > + attrs++; > + } > + > + dev_err(&client->dev, "No coefficients found for register: %x\n", > + attrs->reg); > +
attrs points beyond the array size here, so attrs->reg does not point to a valid array element. The problem would also not be the register this happens to point to, but the class (ie the chip does not support a sensor of the requested class).
Not sure if this should trigger a message or error in the first place. It won't matter since the chip will never need those coefficients. If anything, this would be a misconfiguration (the driver should not set direct format for this sensor class), and the return value should be -EINVAL.
Either case, I wonder if this can be handled with less complex code, ie without having to check data->info->func[] for all pages. How about just walking through attrs and try all class matches until one is found that works (ie not return on error but keep trying) ?
> + return -ENODEV; > +} > + > /* > * Identify chip parameters. > * This function is called for all chips. > @@ -2185,6 +2217,7 @@ static int pmbus_identify_common(struct i2c_client *client, > struct pmbus_data *data, int page) > { > int vout_mode = -1; > + int ret; > > if (pmbus_check_byte_register(client, page, PMBUS_VOUT_MODE)) > vout_mode = _pmbus_read_byte_data(client, page, > @@ -2214,6 +2247,66 @@ static int pmbus_identify_common(struct i2c_client *client, > } > } > > + if (data->flags & PMBUS_USE_COEFFICIENTS_CMD) {
I think there should be a separate function to handle that, to be called only once, not once per page.
> + if (!i2c_check_functionality(client->adapter, > + I2C_FUNC_SMBUS_BLOCK_PROC_CALL)) > + return -ENODEV; > + > + if (data->info->format[PSC_VOLTAGE_IN] == direct) { > + ret = pmbus_init_coefficients(client, data, page, > + PSC_VOLTAGE_IN, > + voltage_attributes, > + ARRAY_SIZE(voltage_attributes)); > + if (ret) > + return ret; > + }
It might be useful to have a little structure with {class, attribute list pointer, attribute list size} and walk through that in a loop instead of repeating essentially the same code multiple times.
> + > + if (data->info->format[PSC_VOLTAGE_OUT] == direct) { > + ret = pmbus_init_coefficients(client, data, page, > + PSC_VOLTAGE_OUT, > + voltage_attributes, > + ARRAY_SIZE(voltage_attributes)); > + if (ret) > + return ret; > + } > + > + if (data->info->format[PSC_CURRENT_IN] == direct) { > + ret = pmbus_init_coefficients(client, data, page, > + PSC_CURRENT_IN, > + current_attributes, > + ARRAY_SIZE(current_attributes)); > + if (ret) > + return ret; > + } > + > + if (data->info->format[PSC_CURRENT_OUT] == direct) { > + ret = pmbus_init_coefficients(client, data, page, > + PSC_CURRENT_OUT, > + current_attributes, > + ARRAY_SIZE(current_attributes)); > + if (ret) > + return ret; > + } > + > + if (data->info->format[PSC_POWER] == direct) { > + ret = pmbus_init_coefficients(client, data, page, > + PSC_POWER, > + power_attributes, > + ARRAY_SIZE(power_attributes)); > + if (ret) > + return ret; > + } > + > + if (data->info->format[PSC_TEMPERATURE] == direct) { > + ret = pmbus_init_coefficients(client, data, page, > + PSC_TEMPERATURE, > + temp_attributes, > + ARRAY_SIZE(temp_attributes)); > + if (ret) > + return ret; > + } > + } > + > pmbus_clear_fault_page(client, page); > return 0; > } > diff --git a/include/linux/pmbus.h b/include/linux/pmbus.h > index f720470b1bab..7fdc282dab5a 100644 > --- a/include/linux/pmbus.h > +++ b/include/linux/pmbus.h > @@ -52,6 +52,14 @@ > */ > #define PMBUS_NO_WRITE_PROTECT BIT(4) > > +/* > + * PMBUS_USE_COEFFICIENTS_CMD > + * > + * When this flag is set the PMBus core driver will use the COEFFICIENTS > + * register to initialize the coefficients for the direct mode format. > + */ > +#define PMBUS_USE_COEFFICIENTS_CMD BIT(5) > + > struct pmbus_platform_data { > u32 flags; /* Device specific flags */ > >
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