[PATCH] powerpc/cpufreq: Add pr_warn() on OPAL firmware failures
From: Vaidyanathan Srinivasan <hidden>
Date: 2014-08-03 09:24:16
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 <redacted> --- Tested on powernv and pseries platforms with v3.16-rc7 kernel. drivers/cpufreq/powernv-cpufreq.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
index bb1d08d..379c083 100644
--- 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(int pstate_id) 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(void) { 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) {