[PATCH AUTOSEL 6.6 32/40] drm/amd/display: fix num_ways overflow error

[Sasha Levin]

From: Samson Tam <samson.tam@xxxxxxx>

[ Upstream commit 79f3f1b66753b3a3a269d73676bf50987921f267 ]

[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@xxxxxxx>
Acked-by: Roman Li <roman.li@xxxxxxx>
Signed-off-by: Samson Tam <samson.tam@xxxxxxx>
Tested-by: Daniel Wheeler <daniel.wheeler@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/gpu/drm/amd/display/dc/dcn32/dcn32_hwseq.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_hwseq.c b/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_hwseq.c
index 018376146d977..be59e1c02f8aa 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_hwseq.c
@@ -214,7 +214,7 @@ 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;
@@ -244,7 +244,8 @@ 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;
@@ -304,7 +305,7 @@ 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);
 
-- 
2.42.0