Re: [PATCH] hwmon, fam15h_power: Add support for two more processors

[Aravind Gopalakrishnan]

On 9/10/2014 3:37 PM, Guenter Roeck wrote:
> On Wed, Sep 10, 2014 at 03:01:36PM -0500, Aravind Gopalakrishnan wrote:
> > On 9/10/2014 12:53 PM, Guenter Roeck wrote:
> > > On Wed, Sep 10, 2014 at 12:02:08PM -0500, Aravind Gopalakrishnan wrote:
> > > > Fam16h,M30h(Mullins) and Fam15hM30h(Kaveri) processors can
> > > > report 'power_crit' value. So, adding their respective device ids.
> > > >
> > > > Also, according to BKDGs, the 'TdpRunAvgAccCap' that show_power()
> > > > uses is valid only on Fam15h, Models 0x0-0xF. On all other processors
> > > > the field is 'Reserved'. So, return error if we are on any other family/model.
> > > >
> > > > Impact on lm-sensors is minimal. On such families, instead of reporting
> > > > Current power value as '0', we now have:
> > > > power1:           N/A
> > > It will result in people complaining to us about it.
> > >
> > > It would be more appropriate to not create the attribute the first place
> > > if it is not supported. Sure, that is a bit more code, but it isn't that bad.
> > > You can simply return -ENODEV for unsupported CPUs from the probe function.
> > >
> > >
> > > > Signed-off-by: Aravind Gopalakrishnan <aravind.gopalakrishnan@xxxxxxx>
> > > > ---
> > > >   drivers/hwmon/fam15h_power.c | 6 ++++++
> > > >   1 file changed, 6 insertions(+)
> > > >
> > > > diff --git a/drivers/hwmon/fam15h_power.c b/drivers/hwmon/fam15h_power.c
> > > > index 4a7cbfa..b69bf7d 100644
> > > > --- a/drivers/hwmon/fam15h_power.c
> > > > +++ b/drivers/hwmon/fam15h_power.c
> > > > @@ -57,6 +57,10 @@ static ssize_t show_power(struct device *dev,
> > > >   	struct fam15h_power_data *data = dev_get_drvdata(dev);
> > > >   	struct pci_dev *f4 = data->pdev;
> > > > +	/* The value TdpRunAvgAccCap is valid only on F15h, Models 0x0-0xF */
> > > > +	if (boot_cpu_data.x86 != 0x15 || boot_cpu_data.x86_model > 0x0)
> > > The comment does not match the code. The comment talks about accepting models
> > > F15h, models 0x0-0xF, but the code rejects anything but F15h model 0x0.
> > Ah. Yes, The condition should have been (..boot_cpu_data.x86_model > 0xf)
> >
> > > Now it may well be that the above describes identifies all F15h and F16h CPUs,
> > > but this is not clear from the comment. It rather looks as if anything but F15h,
> > > model 0x0 is rejected, including all F16h CPUs. But then why accept F16h CPUs
> > > in the first place ?
> > Yes, we want to reject anything but F15h, Models 00h-0fh.
> > The reason I included the newer processor IDs, (and let
> > PCI_DEVICE_ID_AMD_16H_NB_F4) remain
> > is because we can still obtain 'critical power value'. It is only
> > the 'current power' that is not exposed.
> That is a behavioral change, though; previously the current power was
> reported for F16h chips with PCI ID PCI_DEVICE_ID_AMD_16H_NB_F4.
> Is this a bug, ie should the power value not have been reported
> for the F16h chips ?

That's right.

> > If we return -ENODEV in the probe function (or we can just remove
> > the listed PCI_DEVICE_ID), then we'd not get the critical power
> > values too.
> If you want to make the actual power reporting conditional, you should
> introduce an is_visible function to the attribute group to ensure that
> power1_input is only reported if/when supported. If the actual power
> value is not really supported for F16h chips, you should actually provide
> two separate patches: One to make power1_input optional, to be reported for
> supported chips only, and another to add more chips. One is a bug fix,
> the other a functionality extension.

Ok, I'll do that and resend.

Thanks,
-Aravind.

> > > > +		return -ENOSYS;
> > > > +
> > > >   	pci_bus_read_config_dword(f4->bus, PCI_DEVFN(PCI_SLOT(f4->devfn), 5),
> > > >   				  REG_TDP_RUNNING_AVERAGE, &val);
> > > >   	running_avg_capture = (val >> 4) & 0x3fffff;
> > > > @@ -216,7 +220,9 @@ static int fam15h_power_probe(struct pci_dev *pdev,
> > > >   static const struct pci_device_id fam15h_power_id_table[] = {
> > > >   	{ PCI_VDEVICE(AMD, PCI_DEVICE_ID_AMD_15H_NB_F4) },
> > > > +	{ PCI_VDEVICE(AMD, PCI_DEVICE_ID_AMD_15H_M30H_NB_F4) },
> > > >   	{ PCI_VDEVICE(AMD, PCI_DEVICE_ID_AMD_16H_NB_F4) },
> > > > +	{ PCI_VDEVICE(AMD, PCI_DEVICE_ID_AMD_16H_M30H_NB_F3) },
> > > >   	{}
> > > >   };
> > > >   MODULE_DEVICE_TABLE(pci, fam15h_power_id_table);
> > > > --
> > > > 2.0.3

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