Messages in this thread Patch in this message | | | Date | Mon, 19 Jun 2023 13:02:55 -0500 | Subject | Re: [PATCH v3] hwmon: (k10temp) Enable AMD3255 Proc to show negative temperature | From | "Limonciello, Mario" <> |
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On 6/19/2023 12:07 PM, Guenter Roeck wrote: > On 6/19/23 09:54, Baskaran Kannan wrote: >> Industrial processor i3255 supports temperatures -40 deg celcius >> to 105 deg Celcius. The current implementation of k10temp_read_temp >> rounds off any negative >> temperatures to '0'. To fix this, the following changes have been made. >> Added a flag 'disp_negative' to struct k10temp_data to support >> AMD i3255 processors. Flag 'disp_negative' is set if 3255 processor >> is found during k10temp_probe. Flag 'disp_negative' is used to >> determine >> whether to round off negative temperatures to '0' in k10temp_read_temp. >> >> Signed-off-by: Baskaran Kannan <Baski.Kannan@amd.com> > > Now you have made changes you were not asked to make, extended the flag > to cover a range of processors instead of just i3255, and did not provide > a change log nor a comment in the code describing why processors with > certain model numbers should display negative temperatures. > i3255 happens to be one of the industrial processors in family 17h models 01h through 08h. These are potentially used at subzero temperatures and so displaying negative numbers makes a lot sense.
So I think the commit message needs to be be amended to better explain that.
I guided Kannan against leaving a comment in the code with specific models because it either won't age well as other industrial processors are introduced or may need to be ping-ponged each time.
But perhaps it should be more generic like:
/* Industrial processors may be used at sub zero temperatures */
> Guenter > >> --- >> drivers/hwmon/k10temp.c | 8 ++++++-- >> 1 file changed, 6 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/hwmon/k10temp.c b/drivers/hwmon/k10temp.c >> index 7b177b9fbb09..2613420d43ff 100644 >> --- a/drivers/hwmon/k10temp.c >> +++ b/drivers/hwmon/k10temp.c >> @@ -86,6 +86,7 @@ struct k10temp_data { >> u32 show_temp; >> bool is_zen; >> u32 ccd_offset; >> + bool disp_negative; >> }; >> #define TCTL_BIT 0 >> @@ -204,12 +205,12 @@ static int k10temp_read_temp(struct device >> *dev, u32 attr, int channel, >> switch (channel) { >> case 0: /* Tctl */ >> *val = get_raw_temp(data); >> - if (*val < 0) >> + if (*val < 0 && !data->disp_negative) >> *val = 0; >> break; >> case 1: /* Tdie */ >> *val = get_raw_temp(data) - data->temp_offset; >> - if (*val < 0) >> + if (*val < 0 && !data->disp_negative) >> *val = 0; >> break; >> case 2 ... 13: /* Tccd{1-12} */ >> @@ -405,6 +406,9 @@ static int k10temp_probe(struct pci_dev *pdev, >> const struct pci_device_id *id) >> data->pdev = pdev; >> data->show_temp |= BIT(TCTL_BIT); /* Always show Tctl */ >> + if (boot_cpu_data.x86 == 0x17 && boot_cpu_data.x86_model < 0x8) >> + data->disp_negative = true; >> + >> if (boot_cpu_data.x86 == 0x15 && >> ((boot_cpu_data.x86_model & 0xf0) == 0x60 || >> (boot_cpu_data.x86_model & 0xf0) == 0x70)) { >
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