FAILED: patch "[PATCH] drm/amd/display: Fix divide by zero when calculating min ODM" failed to apply to 6.16-stable tree

FAILED: patch "[PATCH] drm/amd/display: Fix divide by zero when calculating min ODM" failed to apply to 6.16-stable tree

[gregkh]

The patch below does not apply to the 6.16-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.16.y
git checkout FETCH_HEAD
git cherry-pick -x 3556dac8289456bc8b28670546b969f543967856
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025082118-unbounded-tarnish-ef1e@gregkh' --subject-prefix 'PATCH 6.16.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 3556dac8289456bc8b28670546b969f543967856 Mon Sep 17 00:00:00 2001
From: Dillon Varone <dillon.varone@amd.com>
Date: Thu, 10 Jul 2025 20:57:37 -0400
Subject: [PATCH] drm/amd/display: Fix divide by zero when calculating min ODM
 factor

[WHY&HOW]
If the debug option is set to disable_dsc the max slice width and/or
dispclk can be zero. This causes a divide by zero when calculating the
min ODM combine factor. Add a check to ensure they are valid first.

Reviewed-by: Wenjing Liu <wenjing.liu@amd.com>
Signed-off-by: Dillon Varone <dillon.varone@amd.com>
Signed-off-by: Wayne Lin <wayne.lin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

diff --git a/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c b/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
index a454d16e6586..1f53a9f0c0ac 100644
--- a/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
+++ b/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
@@ -152,7 +152,7 @@ uint32_t dc_bandwidth_in_kbps_from_timing(
 }
 
 /* Forward Declerations */
-static unsigned int get_min_slice_count_for_odm(
+static unsigned int get_min_dsc_slice_count_for_odm(
 		const struct display_stream_compressor *dsc,
 		const struct dsc_enc_caps *dsc_enc_caps,
 		const struct dc_crtc_timing *timing);
@@ -466,7 +466,7 @@ bool dc_dsc_compute_bandwidth_range(
 		struct dc_dsc_bw_range *range)
 {
 	bool is_dsc_possible = false;
-	unsigned int min_slice_count;
+	unsigned int min_dsc_slice_count;
 	struct dsc_enc_caps dsc_enc_caps;
 	struct dsc_enc_caps dsc_common_caps;
 	struct dc_dsc_config config = {0};
@@ -478,14 +478,14 @@ bool dc_dsc_compute_bandwidth_range(
 
 	get_dsc_enc_caps(dsc, &dsc_enc_caps, timing->pix_clk_100hz);
 
-	min_slice_count = get_min_slice_count_for_odm(dsc, &dsc_enc_caps, timing);
+	min_dsc_slice_count = get_min_dsc_slice_count_for_odm(dsc, &dsc_enc_caps, timing);
 
 	is_dsc_possible = intersect_dsc_caps(dsc_sink_caps, &dsc_enc_caps,
 			timing->pixel_encoding, &dsc_common_caps);
 
 	if (is_dsc_possible)
 		is_dsc_possible = setup_dsc_config(dsc_sink_caps, &dsc_enc_caps, 0, timing,
-				&options, link_encoding, min_slice_count, &config);
+				&options, link_encoding, min_dsc_slice_count, &config);
 
 	if (is_dsc_possible)
 		is_dsc_possible = decide_dsc_bandwidth_range(min_bpp_x16, max_bpp_x16,
@@ -593,14 +593,12 @@ static void build_dsc_enc_caps(
 
 	struct dc *dc;
 
-	memset(&single_dsc_enc_caps, 0, sizeof(struct dsc_enc_caps));
-
 	if (!dsc || !dsc->ctx || !dsc->ctx->dc || !dsc->funcs->dsc_get_single_enc_caps)
 		return;
 
 	dc = dsc->ctx->dc;
 
-	if (!dc->clk_mgr || !dc->clk_mgr->funcs->get_max_clock_khz || !dc->res_pool)
+	if (!dc->clk_mgr || !dc->clk_mgr->funcs->get_max_clock_khz || !dc->res_pool || dc->debug.disable_dsc)
 		return;
 
 	/* get max DSCCLK from clk_mgr */
@@ -634,7 +632,7 @@ static inline uint32_t dsc_div_by_10_round_up(uint32_t value)
 	return (value + 9) / 10;
 }
 
-static unsigned int get_min_slice_count_for_odm(
+static unsigned int get_min_dsc_slice_count_for_odm(
 		const struct display_stream_compressor *dsc,
 		const struct dsc_enc_caps *dsc_enc_caps,
 		const struct dc_crtc_timing *timing)
@@ -651,6 +649,10 @@ static unsigned int get_min_slice_count_for_odm(
 		}
 	}
 
+	/* validate parameters */
+	if (max_dispclk_khz == 0 || dsc_enc_caps->max_slice_width == 0)
+		return 1;
+
 	/* consider minimum odm slices required due to
 	 * 1) display pipe throughput (dispclk)
 	 * 2) max image width per slice
@@ -669,13 +671,12 @@ static void get_dsc_enc_caps(
 {
 	memset(dsc_enc_caps, 0, sizeof(struct dsc_enc_caps));
 
-	if (!dsc)
+	if (!dsc || !dsc->ctx || !dsc->ctx->dc || dsc->ctx->dc->debug.disable_dsc)
 		return;
 
 	/* check if reported cap global or only for a single DCN DSC enc */
 	if (dsc->funcs->dsc_get_enc_caps) {
-		if (!dsc->ctx->dc->debug.disable_dsc)
-			dsc->funcs->dsc_get_enc_caps(dsc_enc_caps, pixel_clock_100Hz);
+		dsc->funcs->dsc_get_enc_caps(dsc_enc_caps, pixel_clock_100Hz);
 	} else {
 		build_dsc_enc_caps(dsc, dsc_enc_caps);
 	}
@@ -1295,10 +1296,10 @@ bool dc_dsc_compute_config(
 {
 	bool is_dsc_possible = false;
 	struct dsc_enc_caps dsc_enc_caps;
-	unsigned int min_slice_count;
+	unsigned int min_dsc_slice_count;
 	get_dsc_enc_caps(dsc, &dsc_enc_caps, timing->pix_clk_100hz);
 
-	min_slice_count = get_min_slice_count_for_odm(dsc, &dsc_enc_caps, timing);
+	min_dsc_slice_count = get_min_dsc_slice_count_for_odm(dsc, &dsc_enc_caps, timing);
 
 	is_dsc_possible = setup_dsc_config(dsc_sink_caps,
 		&dsc_enc_caps,
@@ -1306,7 +1307,7 @@ bool dc_dsc_compute_config(
 		timing,
 		options,
 		link_encoding,
-		min_slice_count,
+		min_dsc_slice_count,
 		dsc_cfg);
 	return is_dsc_possible;
 }