linux-kernel - [PATCH] drm/amd/display: Fix unsigned comparison with less than zero

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Message-Id: <20240701025028.36072-1-jiapeng.chong@linux.alibaba.com>
Date: Mon,  1 Jul 2024 10:50:28 +0800
From: Jiapeng Chong <jiapeng.chong@...ux.alibaba.com>
To: harry.wentland@....com
Cc: sunpeng.li@....com,
	Rodrigo.Siqueira@....com,
	alexander.deucher@....com,
	christian.koenig@....com,
	Xinhui.Pan@....com,
	airlied@...il.com,
	daniel@...ll.ch,
	amd-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	Jiapeng Chong <jiapeng.chong@...ux.alibaba.com>,
	Abaci Robot <abaci@...ux.alibaba.com>
Subject: [PATCH] drm/amd/display: Fix unsigned comparison with less than zero

The return value from the call to dml21_find_dc_pipes_for_plane() is int.
However, the return value is being assigned to an unsigned int variable
'num_pipes', the condition if(num_pipes <= 0) is not rigorous enough,
so making 'num_pipes' an int.

./drivers/gpu/drm/amd/display/dc/dml2/dml21/dml21_wrapper.c:318:6-15: WARNING: Unsigned expression compared with zero: num_pipes <= 0.
./drivers/gpu/drm/amd/display/dc/dml2/dml21/dml21_wrapper.c:360:6-15: WARNING: Unsigned expression compared with zero: num_pipes <= 0.

Reported-by: Abaci Robot <abaci@...ux.alibaba.com>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=9454
Signed-off-by: Jiapeng Chong <jiapeng.chong@...ux.alibaba.com>
---
 .../drm/amd/display/dc/dml2/dml21/dml21_wrapper.c | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dml2/dml21/dml21_wrapper.c b/drivers/gpu/drm/amd/display/dc/dml2/dml21/dml21_wrapper.c
index c310354cd5fc..9d96a31419fa 100644
--- a/drivers/gpu/drm/amd/display/dc/dml2/dml21/dml21_wrapper.c
+++ b/drivers/gpu/drm/amd/display/dc/dml2/dml21/dml21_wrapper.c
@@ -280,7 +280,8 @@ bool dml21_validate(const struct dc *in_dc, struct dc_state *context, struct dml
 
 void dml21_prepare_mcache_programming(struct dc *in_dc, struct dc_state *context, struct dml2_context *dml_ctx)
 {
-	unsigned int num_pipes, dml_prog_idx, dml_phantom_prog_idx, dc_pipe_index;
+	unsigned int dml_prog_idx, dml_phantom_prog_idx, dc_pipe_index;
+	int num_pipes;
 	struct pipe_ctx *dc_main_pipes[__DML2_WRAPPER_MAX_STREAMS_PLANES__];
 	struct pipe_ctx *dc_phantom_pipes[__DML2_WRAPPER_MAX_STREAMS_PLANES__] = {0};
 
@@ -314,10 +315,8 @@ void dml21_prepare_mcache_programming(struct dc *in_dc, struct dc_state *context
 		}
 
 		num_pipes = dml21_find_dc_pipes_for_plane(in_dc, context, dml_ctx, dc_main_pipes, dc_phantom_pipes, dml_prog_idx);
-
-		if (num_pipes <= 0 ||
-				dc_main_pipes[0]->stream == NULL ||
-				dc_main_pipes[0]->plane_state == NULL)
+		if (num_pipes <= 0 || dc_main_pipes[0]->stream == NULL ||
+		    dc_main_pipes[0]->plane_state == NULL)
 			continue;
 
 		/* get config for each pipe */
@@ -356,10 +355,8 @@ void dml21_prepare_mcache_programming(struct dc *in_dc, struct dc_state *context
 		pln_prog = &dml_ctx->v21.mode_programming.programming->plane_programming[dml_prog_idx];
 
 		num_pipes = dml21_find_dc_pipes_for_plane(in_dc, context, dml_ctx, dc_main_pipes, dc_phantom_pipes, dml_prog_idx);
-
-		if (num_pipes <= 0 ||
-				dc_main_pipes[0]->stream == NULL ||
-				dc_main_pipes[0]->plane_state == NULL)
+		if (num_pipes <= 0 || dc_main_pipes[0]->stream == NULL ||
+		    dc_main_pipes[0]->plane_state == NULL)
 			continue;
 
 		/* get config for each pipe */
-- 
2.20.1.7.g153144c