From 682439fffad9fa9a38d37dd1b1318e9374232213 Mon Sep 17 00:00:00 2001
From: Samson Tam <Samson.Tam@amd.com>
Date: Wed, 19 Apr 2023 18:17:14 -0400
Subject: [PATCH] drm/amd/display: filter out invalid bits in pipe_fuses
Git-commit: 682439fffad9fa9a38d37dd1b1318e9374232213
Patch-mainline: v6.4-rc1
References: git-fixes

[Why]
Reading pipe_fuses from register may have invalid bits set, which may
 affect the num_pipes erroneously.

[How]
Add read_pipes_fuses() call and filter bits based on expected number
 of pipes.

Reviewed-by: Alvin Lee <Alvin.Lee2@amd.com>
Acked-by: Alan Liu <HaoPing.Liu@amd.com>
Signed-off-by: Samson Tam <Samson.Tam@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org # 6.1.x
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/amd/display/dc/dcn32/dcn32_resource.c   |   10 +++++++++-
 drivers/gpu/drm/amd/display/dc/dcn321/dcn321_resource.c |   10 +++++++++-
 2 files changed, 18 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_resource.c
@@ -2059,6 +2059,14 @@ static struct resource_funcs dcn32_res_p
 	.retain_phantom_pipes = dcn32_retain_phantom_pipes,
 };
 
+static uint32_t read_pipe_fuses(struct dc_context *ctx)
+{
+	uint32_t value = REG_READ(CC_DC_PIPE_DIS);
+	/* DCN32 support max 4 pipes */
+	value = value & 0xf;
+	return value;
+}
+
 
 static bool dcn32_resource_construct(
 	uint8_t num_virtual_links,
@@ -2101,7 +2109,7 @@ static bool dcn32_resource_construct(
 	pool->base.res_cap = &res_cap_dcn32;
 	/* max number of pipes for ASIC before checking for pipe fuses */
 	num_pipes  = pool->base.res_cap->num_timing_generator;
-	pipe_fuses = REG_READ(CC_DC_PIPE_DIS);
+	pipe_fuses = read_pipe_fuses(ctx);
 
 	for (i = 0; i < pool->base.res_cap->num_timing_generator; i++)
 		if (pipe_fuses & 1 << i)
--- a/drivers/gpu/drm/amd/display/dc/dcn321/dcn321_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn321/dcn321_resource.c
@@ -1622,6 +1622,14 @@ static struct resource_funcs dcn321_res_
 	.retain_phantom_pipes = dcn32_retain_phantom_pipes,
 };
 
+static uint32_t read_pipe_fuses(struct dc_context *ctx)
+{
+	uint32_t value = REG_READ(CC_DC_PIPE_DIS);
+	/* DCN321 support max 4 pipes */
+	value = value & 0xf;
+	return value;
+}
+
 
 static bool dcn321_resource_construct(
 	uint8_t num_virtual_links,
@@ -1664,7 +1672,7 @@ static bool dcn321_resource_construct(
 	pool->base.res_cap = &res_cap_dcn321;
 	/* max number of pipes for ASIC before checking for pipe fuses */
 	num_pipes  = pool->base.res_cap->num_timing_generator;
-	pipe_fuses = REG_READ(CC_DC_PIPE_DIS);
+	pipe_fuses = read_pipe_fuses(ctx);
 
 	for (i = 0; i < pool->base.res_cap->num_timing_generator; i++)
 		if (pipe_fuses & 1 << i)