powerpc/pseries: Fix drc-info mappings of logical cpus to drc-index (775fa495) · Commits · 戴 / test

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 <tyreld@linux.ibm.com> Signed-off-by:

Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/1573449697-5448-3-git-send-email-tyreld@linux.ibm.com

arch/powerpc/platforms/pseries/pseries_energy.c

+10 −13

Original line number	Diff line number	Diff line
		@@ -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 @@ err:
		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++) {

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