3.16-stable review patch. If anyone has any objections, please let me know.
------------------
From: Vaidyanathan Srinivasan <svaidy@xxxxxxxxxxxxxxxxxx>
commit 6174bac8c7ff73a86ae9a967d1c9cadc478023ae upstream.
Cpufreq depends on platform firmware to implement PStates. In case of
platform firmware failure, cpufreq should not panic host kernel with
BUG_ON(). Less severe pr_warn() will suffice.
Add firmware_has_feature(FW_FEATURE_OPALv3) check to
skip probing for device-tree on non-powernv platforms.
Signed-off-by: Vaidyanathan Srinivasan <svaidy@xxxxxxxxxxxxxxxxxx>
Acked-by: Gautham R. Shenoy <ego@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/cpufreq/powernv-cpufreq.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
--- a/drivers/cpufreq/powernv-cpufreq.c
+++ b/drivers/cpufreq/powernv-cpufreq.c
@@ -28,6 +28,7 @@
#include <linux/of.h>
#include <asm/cputhreads.h>
+#include <asm/firmware.h>
#include <asm/reg.h>
#include <asm/smp.h> /* Required for cpu_sibling_mask() in UP configs */
@@ -98,7 +99,11 @@ static int init_powernv_pstates(void)
return -ENODEV;
}
- WARN_ON(len_ids != len_freqs);
+ if (len_ids != len_freqs) {
+ pr_warn("Entries in ibm,pstate-ids and "
+ "ibm,pstate-frequencies-mhz does not match\n");
+ }
+
nr_pstates = min(len_ids, len_freqs) / sizeof(u32);
if (!nr_pstates) {
pr_warn("No PStates found\n");
@@ -131,7 +136,12 @@ static unsigned int pstate_id_to_freq(in
int i;
i = powernv_pstate_info.max - pstate_id;
- BUG_ON(i >= powernv_pstate_info.nr_pstates || i < 0);
+ if (i >= powernv_pstate_info.nr_pstates || i < 0) {
+ pr_warn("PState id %d outside of PState table, "
+ "reporting nominal id %d instead\n",
+ pstate_id, powernv_pstate_info.nominal);
+ i = powernv_pstate_info.max - powernv_pstate_info.nominal;
+ }
return powernv_freqs[i].frequency;
}
@@ -321,6 +331,10 @@ static int __init powernv_cpufreq_init(v
{
int rc = 0;
+ /* Don't probe on pseries (guest) platforms */
+ if (!firmware_has_feature(FW_FEATURE_OPALv3))
+ return -ENODEV;
+
/* Discover pstates from device tree and init */
rc = init_powernv_pstates();
if (rc) {
--
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