Ack: [Precise SRU PATCH 3/3] hwmon: fam15h_power: fix bogus values with current BIOSes

[Leann Ogasawara]

On 06/13/2012 01:52 PM, Tim Gardner wrote:
> From: Andre Przywara <andre.przywara at amd.com>
>
> BugLink: http://bugs.launchpad.net/bugs/1009086
>
> Newer BKDG[1] versions recommend a different initialization value for
> the running average range register in the northbridge. This improves
> the power reading by avoiding counter saturations resulting in bogus
> values for anything below about 80% of TDP power consumption.
> Updated BIOSes will have this new value set up from the beginning,
> but meanwhile we correct this value ourselves.
> This needs to be done on all northbridges, even on those where the
> driver itself does not register at.
>
> This fixes the driver on all current machines to provide proper
> values for idle load.
>
> [1]
> http://support.amd.com/us/Processor_TechDocs/42301_15h_Mod_00h-0Fh_BKDG.pdf
> Chapter 3.8: D18F5xE0 Processor TDP Running Average (p. 452)
>
> Signed-off-by: Andre Przywara <andre.przywara at amd.com>
> Acked-by: Jean Delvare <khali at linux-fr.org>
> [guenter.roeck at ericsson.com: Removed unnecessary return statement]
> Signed-off-by: Guenter Roeck <guenter.roeck at ericsson.com>
> Cc: stable at vger.kernel.org # 3.0+
> (cherry picked from commit 00250ec90963b7ef6678438888f3244985ecde14)
>
> Signed-off-by: Tim Gardner <tim.gardner at canonical.com>

Again hardware specific and low risk of regression.  Also already CC'd
to upstream stable.

Acked-by: Leann Ogasawara <leann.ogasawara at canonical.com>

> ---
>  drivers/hwmon/fam15h_power.c |   39 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 39 insertions(+)
>
> diff --git a/drivers/hwmon/fam15h_power.c b/drivers/hwmon/fam15h_power.c
> index b7494af..37a8fc9 100644
> --- a/drivers/hwmon/fam15h_power.c
> +++ b/drivers/hwmon/fam15h_power.c
> @@ -122,6 +122,38 @@ static bool __devinit fam15h_power_is_internal_node0(struct pci_dev *f4)
>  	return true;
>  }
>  
> +/*
> + * Newer BKDG versions have an updated recommendation on how to properly
> + * initialize the running average range (was: 0xE, now: 0x9). This avoids
> + * counter saturations resulting in bogus power readings.
> + * We correct this value ourselves to cope with older BIOSes.
> + */
> +static void __devinit tweak_runavg_range(struct pci_dev *pdev)
> +{
> +	u32 val;
> +	const struct pci_device_id affected_device = {
> +		PCI_VDEVICE(AMD, PCI_DEVICE_ID_AMD_15H_NB_F4) };
> +
> +	/*
> +	 * let this quirk apply only to the current version of the
> +	 * northbridge, since future versions may change the behavior
> +	 */
> +	if (!pci_match_id(&affected_device, pdev))
> +		return;
> +
> +	pci_bus_read_config_dword(pdev->bus,
> +		PCI_DEVFN(PCI_SLOT(pdev->devfn), 5),
> +		REG_TDP_RUNNING_AVERAGE, &val);
> +	if ((val & 0xf) != 0xe)
> +		return;
> +
> +	val &= ~0xf;
> +	val |=  0x9;
> +	pci_bus_write_config_dword(pdev->bus,
> +		PCI_DEVFN(PCI_SLOT(pdev->devfn), 5),
> +		REG_TDP_RUNNING_AVERAGE, val);
> +}
> +
>  static void __devinit fam15h_power_init_data(struct pci_dev *f4,
>  					     struct fam15h_power_data *data)
>  {
> @@ -155,6 +187,13 @@ static int __devinit fam15h_power_probe(struct pci_dev *pdev,
>  	struct device *dev;
>  	int err;
>  
> +	/*
> +	 * though we ignore every other northbridge, we still have to
> +	 * do the tweaking on _each_ node in MCM processors as the counters
> +	 * are working hand-in-hand
> +	 */
> +	tweak_runavg_range(pdev);
> +
>  	if (!fam15h_power_is_internal_node0(pdev)) {
>  		err = -ENODEV;
>  		goto exit;