Messages in this thread |  | | Subject | Re: [PATCH v2 3/6] hwmon: (pmbus/pim4328) Add support for reading direct format coefficients | From | Guenter Roeck <> | Date | Sun, 23 May 2021 12:47:46 -0700 |
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On 5/23/21 10:52 AM, Erik Rosen wrote: > On Sat, May 22, 2021 at 3:41 PM Guenter Roeck <linux@roeck-us.net> wrote: >> >> 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) ? > > Ok, I'll send a new version based on your comments. > I'm not entirely comfortable with just silently ignoring any failure to > retrieve the coefficients for a sensor class. I mean it could be due to any > reason; a bus error for instance. I'll return a -EINVAL for now if you don't > disagree. > Ok. After all, it does suggest a misconfiguration.
Thanks, Guenter
> /Erik > >> >>> + 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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