> -----Original Message----- > From: Guenter Roeck <groeck7@xxxxxxxxx> On Behalf Of Guenter Roeck > Sent: Tuesday, November 7, 2023 11:30 AM > To: Delphine_CC_Chiu/WYHQ/Wiwynn <Delphine_CC_Chiu@xxxxxxxxxx>; > patrick@xxxxxxxxx; Jean Delvare <jdelvare@xxxxxxxx>; Jonathan Corbet > <corbet@xxxxxxx> > Cc: Rob Herring <robh+dt@xxxxxxxxxx>; Krzysztof Kozlowski > <krzysztof.kozlowski+dt@xxxxxxxxxx>; Conor Dooley <conor+dt@xxxxxxxxxx>; > linux-i2c@xxxxxxxxxxxxxxx; linux-hwmon@xxxxxxxxxxxxxxx; > devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > linux-doc@xxxxxxxxxxxxxxx > Subject: Re: [PATCH v2 2/2] hwmon: pmbus: Add ltc4286 driver > > Security Reminder: Please be aware that this email is sent by an external > sender. > > On 11/6/23 19:08, Delphine_CC_Chiu/WYHQ/Wiwynn wrote: > >> -----Original Message----- > >> From: Guenter Roeck <groeck7@xxxxxxxxx> On Behalf Of Guenter Roeck > >> Sent: Tuesday, October 31, 2023 9:47 PM > >> To: Delphine_CC_Chiu/WYHQ/Wiwynn <Delphine_CC_Chiu@xxxxxxxxxx>; > >> patrick@xxxxxxxxx; Jean Delvare <jdelvare@xxxxxxxx>; Jonathan Corbet > >> <corbet@xxxxxxx> > >> Cc: Rob Herring <robh+dt@xxxxxxxxxx>; Krzysztof Kozlowski > >> <krzysztof.kozlowski+dt@xxxxxxxxxx>; Conor Dooley > >> <conor+dt@xxxxxxxxxx>; linux-i2c@xxxxxxxxxxxxxxx; > >> linux-hwmon@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; > >> linux-kernel@xxxxxxxxxxxxxxx; linux-doc@xxxxxxxxxxxxxxx > >> Subject: Re: [PATCH v2 2/2] hwmon: pmbus: Add ltc4286 driver > >> > >> Security Reminder: Please be aware that this email is sent by an > >> external sender. > >> > >> On 10/30/23 23:46, Delphine_CC_Chiu/WYHQ/Wiwynn wrote: > >> [ ... ] > >>>> > >>>>> + > >>>>> + ret = of_property_read_u32(client->dev.of_node, > >>>>> + "shunt-resistor-micro-ohms", > >>>> &rsense); > >>>>> + if (ret < 0) > >>>>> + return ret; > >>>>> + > >>>>> + if (rsense == 0) > >>>>> + return -EINVAL; > >>>>> + > >>>>> + info = <c4286_info; > >>>>> + > >>>>> + /* Default of VRANGE_SELECT = 1, 102.4V */ > >>>>> + if (device_property_read_bool(&client->dev, > >>>> "adi,vrange-select-25p6")) { > >>>> > >>>> What if the adi,vrange-select-25p6 property is not provided, but > >>>> the chip is programmed for this range ? > >>> The binding document tells programmers how to fill the dts. > >>> Thus, programmers must fill this property if their system is 25.6 > >>> volts voltage > >> range. > >>> > >> > >> Sure, but there is no else case, meaning VRANGE_SELECT is unmodified > >> in that case. There is no guarantee that the chip is in its power-on state. > > > > The else case is in v2 ltc4286.c line 133 It means that the voltage > > range for programmer is 102.4 volts which is default value, so driver > > doesn't need to do any change for VRANGE_SELECT bit. > > There is no guarantee that the value wasn't changed before the driver was > loaded. We still can’t get your point. Could you tell us about your concern here? Thanks. > > Guenter > > > Additionally, we have checked the behavior of VRANGE_SELECT bit with > vendor. > > Below is the reply from vendor: > > [Our question] > > If we change the VRANGE_SELECT bit value to 0, the value would return to > default after we restart this device? > > Or VRANGE_SELECT bit value would never change util someone change its > value? > > [ADI reply] > > chip reset will go back to default. Thanks. > > > > Thus, we must overwrite this bit if the user fill > > adi,vrange-select-25p6 here whenever driver probes > > > >> > >> Guenter > >