[PATCH] Remove Barcelona Thermal Throttling

[Russell Leidich]

All,

You can imagine my dismay when I recently learned that, after all our
collective effort, hardware thermal throttling does not work reliably
on Barcelona, according to AMD.  Due to NDA restrictions, I am unable
to provide further details.

But the effort has not been a waste; whenever AMD manages to make a
reliable hardware thermal sensor, this code should "just work" along
with all the other northbridge initialization associated with the
device IDs in k8_northbridges[].

This patch Blacklists Barcelona as non-hardware-thermal-throttlable
(in addition to RevF, which was already blacklisted).  On the
recommendation of my colleagues, it also contains these politeness
enhancements: (1) warns the user if the CPU is _not_ blacklisted, but
the BIOS neglected to enable thermal throttling (as a safety measure)
and (2) uses the PCI_SLOT macro instead of the more obnoxious
shift-right-by-3 to compute PCI device numbers.

This patch assumes that it is being applied _after_ my previous patch
has already been integrated.  I mailed out that patch on 1/17/2008
with subject "Re: [PATCH] AMD Thermal Interrupt Support".
-- 
Russell Leidich
Signed-off-by: Russell Leidich <rml@xxxxxxxxxx>
--- linux-2.6.24-rc5.orig/arch/x86/kernel/cpu/mcheck/mce_amd_64	2008-02-03 21:17:58.186613000 -0800
+++ linux-2.6.24-rc5/arch/x86/kernel/cpu/mcheck/mce_amd_64.c	2008-02-03 21:51:38.810989000 -0800
@@ -742,13 +742,20 @@ static void smp_thermal_northbridge_init
 		 */
 		pci_read_config_dword(k8_northbridges[nb_num],
 					THERM_CTL_F3X64, &therm_ctl_f3x64);
-		therm_ctl_f3x64 |= PSL_APIC_HI_EN | HTC_EN;
+		therm_ctl_f3x64 |= PSL_APIC_HI_EN;
 		therm_ctl_f3x64 &= (~PSL_APIC_LO_EN);
 		pci_write_config_dword(k8_northbridges[nb_num],
 					THERM_CTL_F3X64, therm_ctl_f3x64);
-		printk(KERN_INFO "CPU thermal throttling interrupts enabled in "
-			"PCI bus 0x0, device 0x%x, function 0x3, register 0x64."
-			"\n", k8_northbridges[nb_num]->devfn >> 3);
+		if (therm_ctl_f3x64 & HTC_EN)
+			printk(KERN_INFO "CPU thermal throttling interrupts "
+				"enabled in PCI bus 0x0, device 0x%x, function "
+				"0x3, register 0x64.\n",
+				PCI_SLOT(k8_northbridges[nb_num]->devfn));
+		else
+			printk(KERN_WARNING "CPU thermal throttling disabled by"
+				" the BIOS in PCI bus 0x0, device 0x%x, "
+				"function 0x3, register 0x64, bit 0x0.\n",
+				PCI_SLOT(k8_northbridges[nb_num]->devfn));
 	}
 }
 
@@ -835,7 +842,7 @@ static void smp_thermal_early_throttle_c
  * corresponding APIC initialization on each core.
  *
  * Due to an erratum involving the thermal sensor, this code does not work on
- * any CPU prior to Family 0x10.
+ * CPUs with certain northbridge device IDs, as coded below.
  */
 static int smp_thermal_interrupt_init(void)
 {
@@ -844,13 +851,15 @@ static int smp_thermal_interrupt_init(vo
 	if (num_k8_northbridges == 0)
 		goto out;
 	/*
-	 * If any of the northbridges has PCI ID 0x1103, then its thermal
-	 * hardware suffers from an erratum which prevents this code from
-	 * working, so abort.  (This implies that it only works on Family
-	 * 0x10.)
+	 * If any of the northbridges has any of the device IDs in the following
+	 * loop, then the hardware suffers from an erratum which prevents
+	 * this code from working, so abort.
 	 */
 	for (nb_num = 0; nb_num < num_k8_northbridges; nb_num++) {
-		if ((k8_northbridges[nb_num]->device) == 0x1103)
+		__u32 device_id;
+
+		device_id = k8_northbridges[nb_num]->device;
+		if ((device_id == 0x1103) || (device_id == 0x1203))
 			goto out;
 	}
 	/*