[PATCH] drm/amd/powerplay: revise caching the soft pptable and add it's size

[Alex Deucher]

From: Eric Huang <JinHuiEric.Huang at amd.com>

This fixes a bug in the pptable access interface that could lead to
a crash.  Check the pointer before using it.

Reviewed-by: Alex Deucher <alexander.deucher at amd.com>
Signed-off-by: Eric Huang <JinHuiEric.Huang at amd.com>
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
---
 .../gpu/drm/amd/powerplay/hwmgr/tonga_processpptables.c   | 15 +++++++++------
 drivers/gpu/drm/amd/powerplay/inc/hwmgr.h                 |  1 +
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/powerplay/hwmgr/tonga_processpptables.c b/drivers/gpu/drm/amd/powerplay/hwmgr/tonga_processpptables.c
index 96a2787..10e3630 100644
--- a/drivers/gpu/drm/amd/powerplay/hwmgr/tonga_processpptables.c
+++ b/drivers/gpu/drm/amd/powerplay/hwmgr/tonga_processpptables.c
@@ -138,12 +138,15 @@ const void *get_powerplay_table(struct pp_hwmgr *hwmgr)
 
 	u16 size;
 	u8 frev, crev;
-	void *table_address;
-
-	table_address = (ATOM_Tonga_POWERPLAYTABLE *)
-		cgs_atom_get_data_table(hwmgr->device, index, &size, &frev, &crev);
-
-	hwmgr->soft_pp_table = table_address;	/*Cache the result in RAM.*/
+	void *table_address = (void *)hwmgr->soft_pp_table;
+
+	if (!table_address) {
+		table_address = (ATOM_Tonga_POWERPLAYTABLE *)
+				cgs_atom_get_data_table(hwmgr->device,
+						index, &size, &frev, &crev);
+		hwmgr->soft_pp_table = table_address;	/*Cache the result in RAM.*/
+		hwmgr->soft_pp_table_size = size;
+	}
 
 	return table_address;
 }
diff --git a/drivers/gpu/drm/amd/powerplay/inc/hwmgr.h b/drivers/gpu/drm/amd/powerplay/inc/hwmgr.h
index b1a9ae5..c96e5b1 100644
--- a/drivers/gpu/drm/amd/powerplay/inc/hwmgr.h
+++ b/drivers/gpu/drm/amd/powerplay/inc/hwmgr.h
@@ -577,6 +577,7 @@ struct pp_hwmgr {
 	void *device;
 	struct pp_smumgr *smumgr;
 	const void *soft_pp_table;
+	uint32_t soft_pp_table_size;
 	bool need_pp_table_upload;
 	enum amd_dpm_forced_level dpm_level;
 	bool block_hw_access;
-- 
2.5.5