drm/amd/display: fix num_ways overflow error

[ Upstream commit 79f3f1b ]

[Why]
Helper function calculates num_ways using 32-bit.  But is
 returned as 8-bit.  If num_ways exceeds 8-bit, then it
 reports back the incorrect num_ways and erroneously
 uses MALL when it should not

[How]
Make returned value 32-bit and convert after it checks
 against caps.cache_num_ways, which is under 8-bit

Reviewed-by: Alvin Lee <alvin.lee2@amd.com>
Acked-by: Roman Li <roman.li@amd.com>
Signed-off-by: Samson Tam <samson.tam@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/gpu/drm/amd/display/dc/dcn32/dcn32_hwseq.c

@@ -216,7 +216,7 @@ static bool dcn32_check_no_memory_request_for_cab(struct dc *dc)
 static uint32_t dcn32_calculate_cab_allocation(struct dc *dc, struct dc_state *ctx)
 {
 	int i;
-	uint8_t num_ways = 0;
+	uint32_t num_ways = 0;
 	uint32_t mall_ss_size_bytes = 0;
 
 	mall_ss_size_bytes = ctx->bw_ctx.bw.dcn.mall_ss_size_bytes;
@@ -246,7 +246,8 @@ static uint32_t dcn32_calculate_cab_allocation(struct dc *dc, struct dc_state *c
 bool dcn32_apply_idle_power_optimizations(struct dc *dc, bool enable)
 {
 	union dmub_rb_cmd cmd;
-	uint8_t ways, i;
+	uint8_t i;
+	uint32_t ways;
 	int j;
 	bool mall_ss_unsupported = false;
 	struct dc_plane_state *plane = NULL;
@@ -306,7 +307,7 @@ bool dcn32_apply_idle_power_optimizations(struct dc *dc, bool enable)
 				cmd.cab.header.type = DMUB_CMD__CAB_FOR_SS;
 				cmd.cab.header.sub_type = DMUB_CMD__CAB_DCN_SS_FIT_IN_CAB;
 				cmd.cab.header.payload_bytes = sizeof(cmd.cab) - sizeof(cmd.cab.header);
-				cmd.cab.cab_alloc_ways = ways;
+				cmd.cab.cab_alloc_ways = (uint8_t)ways;
 
 				dm_execute_dmub_cmd(dc->ctx, &cmd, DM_DMUB_WAIT_TYPE_NO_WAIT);