There are a couple subtle errors in the mapping between cpu-ids and a cpus associated drc-index when using the new ibm,drc-info property.
The first is that while drc-info may have been a supported firmware feature at boot it is possible we have migrated to a CEC with older firmware that doesn't support the ibm,drc-info property. In that case the device tree would have been updated after migration to remove the ibm,drc-info property and replace it with the older style ibm,drc-* properties for types, indexes, names, and power-domains. PAPR even goes as far as dictating that if we advertise support for drc-info that we are capable of supporting either property type at runtime. The second is that the first value of the ibm,drc-info property is the int encoded count of drc-info entries. As such "value" returned by of_prop_next_u32() is pointing at that count, and not the first element of the first drc-info entry as is expected by the of_read_drc_info_cell() helper. Fix the first by ignoring DRC-INFO firmware feature and instead testing directly for ibm,drc-info, and then falling back to the old style ibm,drc-indexes in the case it doesn't exit. Fix the second by incrementing value to the next element prior to parsing drc-info entries. Signed-off-by: Tyrel Datwyler <tyr...@linux.ibm.com> --- arch/powerpc/platforms/pseries/pseries_energy.c | 23 ++++++++++------------- 1 file changed, 10 insertions(+), 13 deletions(-) diff --git a/arch/powerpc/platforms/pseries/pseries_energy.c b/arch/powerpc/platforms/pseries/pseries_energy.c index a96874f..09e98d3 100644 --- a/arch/powerpc/platforms/pseries/pseries_energy.c +++ b/arch/powerpc/platforms/pseries/pseries_energy.c @@ -36,6 +36,7 @@ static int sysfs_entries; static u32 cpu_to_drc_index(int cpu) { struct device_node *dn = NULL; + struct property *info; int thread_index; int rc = 1; u32 ret = 0; @@ -47,20 +48,18 @@ static u32 cpu_to_drc_index(int cpu) /* Convert logical cpu number to core number */ thread_index = cpu_core_index_of_thread(cpu); - if (firmware_has_feature(FW_FEATURE_DRC_INFO)) { - struct property *info = NULL; + info = of_find_property(dn, "ibm,drc-info", NULL); + if (info) { struct of_drc_info drc; int j; u32 num_set_entries; const __be32 *value; - info = of_find_property(dn, "ibm,drc-info", NULL); - if (info == NULL) - goto err_of_node_put; - value = of_prop_next_u32(info, NULL, &num_set_entries); if (!value) goto err_of_node_put; + else + value++; for (j = 0; j < num_set_entries; j++) { @@ -110,6 +109,7 @@ static u32 cpu_to_drc_index(int cpu) static int drc_index_to_cpu(u32 drc_index) { struct device_node *dn = NULL; + struct property *info; const int *indexes; int thread_index = 0, cpu = 0; int rc = 1; @@ -117,21 +117,18 @@ static int drc_index_to_cpu(u32 drc_index) dn = of_find_node_by_path("/cpus"); if (dn == NULL) goto err; - - if (firmware_has_feature(FW_FEATURE_DRC_INFO)) { - struct property *info = NULL; + info = of_find_property(dn, "ibm,drc-info", NULL); + if (info) { struct of_drc_info drc; int j; u32 num_set_entries; const __be32 *value; - info = of_find_property(dn, "ibm,drc-info", NULL); - if (info == NULL) - goto err_of_node_put; - value = of_prop_next_u32(info, NULL, &num_set_entries); if (!value) goto err_of_node_put; + else + value++; for (j = 0; j < num_set_entries; j++) { -- 2.7.4